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ECE Aspects of Zero-Energy House - Worcester Polytechnic Institute

1. ECE Aspects of Zero Energy House A Major Qualifying Project Report Submitted to the faculty in the Electrical and Computer Engineering Department at WORCESTER POLYTECHNIC INSTITUTE In partial fulfillment of the requirements for the Degree of Bachelor of Science Submitted on April 26 2013 Submitted by Claude Reynald C Lecorps Electrical and Computer Engineering 13 Submitted to Project Advisor Susan M Jarvis Electrical and Computer Engineering WPI Table of Contents ECE Aspects of Zero Energy House is 1 Le ele Ee En EE 5 e De EE 6 1 Executive SUMMAPY E 7 1 1 PV system MRT dash 8 1 2 Energy Management ecc da name dee EE E Eed 8 2a Marketing iaa at da Ta 10 2 1 Existing Monitoring SYSteM ooooococococnnncnnncnnnnnnncnoncnnncnnnnnnn nono nono nono nn nn nono nono nn nono nnrnnnnnnnnnnornnnnnnnnnnos 11 2 1 1 Production monitoring system Prior Art 11 2 1 2 Consumption Monitoring viii sidad aid ee 17 2 2 Design Requirements sa eegne ege dEAEEEE SEENEN sae sccddsbaccces saaccaed ENEE sasecedesnas ccd SES ee REESEN 21 2 2 1 Communication Block Technical Requirements ararnrrrnnrrannnnnnvnvvennnnnnnnnvnvnnserssrnnnnnnnnsnnenne 22 2 2 2 input Block Requirements escasas need 22 2 2 3 Measurement Block Requirements cccccccessssssecececessessaeeeeeeecesseeeaeseeeescesseaeaeeeeeesseeeegs 22 2 2 4 Beer Blokk sispaspa ae a E E e leddene 23 2 2 5 OaSiS SUMIMANY e CT IN EE 24 3 Design and Implementation nn
2. lighthouses and railroad crossings However the targeted market consists of residential PV system owners which is currently a growing percentage of the energy market due to the dramatically increasing number of solar panel installations From 2009 to 2010 the residential solar PV market average growth rate increased from over 40 per year to 68 Y and by the end of 2010 over 2 600 installations statewide occurred in the state of Massachusetts alone Y Due to this growth the cost of installation is expected to decrease by at least 45 by 2020 In addition according to the Department of Energy DOE The value of the energy provided by these solar systems will increase through advanced communication interfaces and controls while the reliability of electrical service both for solar and non solar a 5 customers will also increase making the monitoring system is worth the time money and effort Oasis the energy management system must meet the needs of the user and the installation technician involved should one be needed in the development and building of zero energy houses the technicians being the students involved with the Solar Decathlon China 2013 The system must be safe accurate and reliable prioritized in that order The system must also be compatible with existing systems to ease installation To maximize accuracy features such as individual panel monitoring and both graphical and numerical performance mod
3. To minimize the energy used by the HVAC system the house was design to passively maintain a comfort level chosen by the competition coordinators The house was insulated and 32 heated passively through solar heat gain using double pane glass windows As for passive cooling the raised atrium roof was made opaque and the atrium windows shown in figure 3 4 were suggested to be replaced by bifacial solar panel for additional shade Furthermore the house has a green roof for addition leak protection and cooling Figure 3 4 Solatrium 3 1 2 System calculations A Energy To determine the size of the PV system first we need to know exactly how much energy is needed The total energy is the sum of all the other loads energy usage Each load s energy usage is the product of their rated power and the amount of time they were active 1 Energy time h Power kVA PF All the calculations were made under the assumption that the power factor was unity 2 Total energy needed Energy HVAC Energy Hot Water Energy appliances Given the energy used by the HVAC system that were estimated directly through Ecotect and the competition schedule the HVAC will use 8 97 kWh per comp day As for the other two 33 loads the detailed competition schedule was used to calculate the total amount of active time for each appliance and for the hot water system To estimate how much energy was used by the hot water system and all th
4. are connected per inverter but the price of the inverter and the extra equipment can cost all together up to 3427 extra Inverter independence eliminates this issue It is also a crucial feature of Oasis because team BEMANY had not yet implemented all of the PV system designs therefore invertor dependence 16 would stifle completion of the system given the time constraint Without a proper monitoring system team BEMANY would not know how much power they are producing or consuming unless someone constantly watches over the meter located outside of the house Thus having a monitoring is important to ttam BEMANY because superfluous energy consumption is likely to be undetected which would result in losing the competition As for residential PV system owner this undetected unwanted behavior would delay the return on investment 2 1 2 Consumption Monitoring As mentioned before the consumption monitoring systems vary in degrees of depth therefore can be broken down by this characteristic Most systems of measure the overall power consumption of a house thus are very simple quick to install and very reliable Contrary to these whole home solutions are targeted systems or devices that measure the power consumption of individual appliances or outlets This is preferable for applications that require a more detailed outlook on the consumption characteristics of a house Targeted systems therefore involve more hardware thus can be more expensiv
5. back to 3 as it should be as you can see in figures 3 8 through 3 12 the timing diagrams resembled the ones in the ADC s datasheet 44 but the results were still very inaccurate Later the source of the error was confirmed to be typos in the datasheet Tek PL Acq Complete M Pos 2 360 45 SAVE REC E i About a D Saving Ai Images ER ECKE UUA k d s ket ho Folder di DN MSB XO X AX Viss Save e f TEKOO24 JPG CHi Lon CH2 500 Mis CH3 7 1 604 Current Folder is AX Figure 3 8 Writing timing diagram Figure 3 9 Accessing the clock register Tek JL Acq Complete M Pos 10 80 05 CURSOR i t Type dn i Source i CH1 at 17 80 us de 56 1 kHz i Cursor 2 10 815 1 0 00 CH1 5 00 CH2 5 00 M 500 05 CH3 1 90 CH3 S 00 CH4 5 004 15 Feb 13 20 06 lt 10Hz Figure 3 10 Setting the clock register to OxA5 Where from top waveform to the bottom channel 4 is the chip select channel 2 is the ADC s SPI output channel 3 is the SPI clock and channel 1 is the ADC s SPI input 45 Tek AL Acq Complete M Pos 400005 CURSOR Type Source at 8 500 05 Ze 117 6kHz av 4 80V dr a Pm P P A el eT s pk enn TNT PRAN it he 3 Uu JAUKU sax VA HVU e RE Ri 200mv on Fe OOO Si el CHT 500 CH2 500V Mis CH 340 CH3 5 00 CH4 5004 15 Feb 13 20 17 lt 10Hz Figure 3 11 Reading timing diagram Figure 3 12 Reading the
6. does not rely on an AC adaptor for power though that option is available for redundancy The majority of components that make up the system are RoHS compliant 24 3 Design and Implementation 3 1 PV system Design The goal for all Solar Decathlon competitions is to build of a Zero energy house One of the rules regarding the photovoltaic PV system is that energy storage devices that have a capacity greater than 100 mWh are prohibited thus the PV system of choice was a 7 kW grid tied system As the one line diagram in Appendix D describes the system consist of an array of solar panel whose power will go into a combiner box be converted to from DC to AC passed through several safety devices Ground Fault interrupter AC and DC disconnect and tied to the village grid The purpose of the safety devices will be expanded upon further in this chapter To determine the size of the PV array all the loads i e the appliances and mechanical loads were chosen and calculated To determine the total minimum amount energy the PV array would need to produce during the competition period the loads required input power were multiplied by how long each individual load would be operational given the competition schedule provided by the Solar Decathlon China 2013 competition coordinator In an attempt to maximize energy efficiency and minimize the size and cost of the PV array a few changes to house were recommended By using the metrological infor
7. router to upload the data to a website This website served as the graphic user interface for the entire system 1 Executive Summary This project explores the design of a photovoltaic PV system and implemented the Energy Management system for said PV system The complete system s purpose was to improve Team BEMANY s odds of winning the energy balance contest of Solar Decathlon China 2013 competition In an effort to promote solar energy the Department of Energy challenged collegiate teams to design build and operate solar powered houses that are cost effective energy efficient and attractive through the creation of the first Solar Decathlon This competition grew in popularity across the globe Since then two other competitions came to existence namely Solar Decathlon Europe which took place in Spain and the Solar Decathlon China 2013 The winner of the overall competition is decided based on four qualitative and six quantitative contests Qualitatively jurors who are experts in their respective fields such as architecture mechanical engineering and communications award points for features of the house that cannot be measured numerically such as aesthetics practicality and design inspiration As for the quantitative contest each team can earn points by completing household tasks such as cooking washing dishes drawing hot water doing laundry and maintaining set indoor temperature and humidity levels Completing these tas
8. the wireless transceiver which was implemented using an XBee ZB The cost could also be reduced by implementing the DMM using an Arduino UNO which is smaller and less expensive 61 ECE Aspects of Zero Energy House than the Arduino Mega 2560 This would require a smaller housing than the one made in this revision In addition a housing would need to be made for the switching network which itself could be optimized using surface mounted decoders and a printed circuit board PCB Since the input stage of the DMM is being revised the power connector which would carry the output voltage of the selected panel to the DMM needs to be implemented using a connector rated for at least 600V and 1A Ideally this would be a BD connector as shown below where the other wire would be earth ground Figure 5 1 BD connector 3 5 mm pitch The next block in need of optimization is the sensor network This network consisted of the hall effect sensors which need a housing to shield to electronic components and well as the ring concentrator In the design the ring concentrators were estimated for 7 Gauss per Amp This design would result in resolution in the order of micro amps so the gain of the concentrator could be lowered so that less material ferrite or cold rolled steel is used per sensors As for the power blocks the boost converters as they are can be modeled using an open loop control diagram This should be modified so that it is self adju
9. was designed and order but did not arrive before the time limit came to pass Battery charger Ideally the battery charger would be capable of fully recharging the main battery after 4 hours from a 70 discharge while not hindering the battery s life expectancy Given these criteria the MCP73833 Lithium Battery charger chosen from my 2799 project was appropriate 57 ECE Aspects of Zero Energy House so it was also used However the output is that of the battery s voltage so a boost converter was mandatory To implement said boost converter the least expensive option capable of outputting SV at 200 mA was chosen from Digikey which was the TPS63002 Test results For the same reason mentioned previously this block was not tested or implemented 3 3 Server Summary Unfortunately the power block was not implemented within the limit and the majority of the functionality lies within the scope of a Computer Science project however the skills acquired for designing and implementing a PCB with the conceptual blocks shown in figure 3 19 in green are PoE Module Buck Converter Ag9000 9V output MCP16323 5V output invaluable MCP73833 Battery ez charger Li Po Battery 3 7 V ping oost Converter 1400mAh TPS63002 5V output 200 mA Worcester Polytechnic Institute Figure 3 19 Server updated conceptual block diagram 58 ECE Aspects of Zero Energy House 4 PV system Design change This chapter describ
10. were all donated by GE which caused the minimum size of the PV array to increase from 7 10 kW to 8 04 kW This change may seem small but it is a financial increase of 2810 The full list of appliances can be found in Appendix C 2 In summary the total energy consumption increased by 89 34 kWh for the entirety of the competition A Mechanical Loads Overall the mechanical load increased by 7 78 kWh This was due to the increase in the HVAC load in spite of the decrease in energy used for plumbing The HVAC module used were four mini split system and the module themselves were York As for the hot water GE s hybrid stand alone solution was used less energy in comparison to the solar hot water design under worst case scenario This yielded 1 62 kWh less 4 2 PV system design conclusion Although all the recommended designs were not implemented Solatrium will have a positive net balance if at least 26 panels are installed during the building phase of the competition This minimum would be a 7 54 kW system which would yield a net of approximately 4 43 kWh At most an 8 12 kW system 28 panels is needed which would result in a net of approximately 25 97 kWh but if all of the panels are used this 11 6 kW system will result in a net of 170 06 kWh 60 ECE Aspects of Zero Energy House 5 Oasis further development This project involved the hardware and software development of Oasis a stand alone energy monitoring and management syste
11. 3 1 4 0 20 296 PIC 39 1 51 3 0 3 0 14 2 Spinneret 33 0995 1 74 98 3 1 3 1 19 3801 Rascal 50 2 175 0 0 2 2 14 As shown in table 4 the value analysis clearly shows that the mbed is the best choice However the HTTP library essentially broke during the design phase so the choices were re evaluated while excluding cost as a factor This was done by assigning a price score of 5 to every option and the Rascal was the clear winner as shown in table 5 Table 5 Server development board design options and revisited scores price additional additional Bonus Score Dev Board area support price score components task Features mbed 13 52 2 59 5 1 4 0 28 296 PIC 39 1 51 5 0 3 0 22 2 Spinneret 33 0995 1 74 98 5 1 3 1 27 3801 Rascal 50 2 175 5 0 2 2 34 Test results The rascal had a built in testing platform to check that all the pins were functioning accordingly This platform was used to confirm that the board was not defective Indeed the board was working properly 55 ECE Aspects of Zero Energy House As for the power budget of the Server the rascal and the XBee ZB together pulled 0 21 A from the power supply when initializing However an accident occurred which was recovered by replacing the 3 3Vsource on the board but the current draw grew 0 52 A This explained why the 7805 linear voltage regulator on the board got very hot This 7805 steps the 9V so
12. 3 2 Conceptual Hot water one line diagram Simply put the glycol within solar collector tubing is heated and carries the heat into a small tank The heat then is then diffused into the water within this tank Thus the temperature of the water coming into the direct hot water heater is closer to the desired temperature making change in temperature if needed much smaller The amount of energy used by the direct hot water heater is proportional to the change in temperature that it needs to provide the change in temperature being the difference between the set temperature and the temperature of the incoming water Should the temperature of the incoming water be higher than the set temperature the direct hot water will simply remain inactive Thankfully SECUSOL had a drain back solar hot water system that had a direct hot water unit built into it shown in figure 3 3 Under the worst cases scenario i e without the solar hot 28 water s assistance the total energy used by the hot water system is 3 08 kWh for the competition period Figure 3 3 SECUSOL Hot water appliance B Appliances The appliances that were required were that of a typical American home refrigerator cooktop range microwave dishwasher home entertainment system television computer sound system lighting clothes washer and dryer In general the appliances that were considered include brands from other zero energy houses from the past competitions and major br
13. 5256 mAh Note the minimum capacity was calculated with a 20 surplus margin to account for voltage mismatch Value Analysis The comparison between lithium ion and lithium polymer based on their DoD specific energy specific power and normalized cost was done during my ECE 2799 which concluded that a Li Po battery was the best choice Since I still had a 6600 mAh Li Po battery from my ECE 2799 project I decided to use it This does the maximum battery capacity of the Solar Decathlon Competition so for the competition the DMM would have to be plugged into a receptacle if the competition coordinator did not overlook it Using this battery the total energy available was 17094 mWh given a restriction to 70 discharge Given the 10 mW power required to operate the DMM this battery will only last 2 34 months The desired three months would be achieved with a Lithium Polymer battery with at least 8455 6 mAh 51 Boost converter A boost convertor is a DC DC switch mode converter that increases it input voltage by decreasing its output current Since the battery is a 3 7V and the microcontroller operates with 5V this convertor is mandatory Since the development board of the microcontroller has regulated 3 3V and 5V only one is necessary Value Analysis Of the boost convertor IC available on Digikey the least expensive option which was the LT1111 was chosen The buck boost IC s recommended setup for a 5V output from the datashee
14. Energy Center Home Heating and Cooling Home Series 2 Online Available http www iowaenergycenter org wp content uploads 2012 03 HomeSeries2 pdf US Department of Energy The History of Solar Online Available http www1 eere energy gov solar pdfs solar_timeline pdf Galen Barbose et al 2010 December Tracking the Sun Ill The Installed Cost of Photovoltaics in the U S from 1998 2009 Online Available http eetd Ibl gov ea emp reports Ibnl 4121e pdf Massachusetts Clean Energy Center Going Solar in Massachusetts Online Available http www masscec com index cfm cdid 11663 pid 11150 International Renewable Energy Agency 2012 RENEWABLE ENERGY TECHNOLOGIES COST ANALYSIS SERIES Solar Photovoltaics Volume 1 Power Sector Issue 4 5 Online Available http www irena org DocumentDownloads Publications RE Technologies Cost Analysis SOLAR PV pdf U S Department of Energy SOLAR ENERGY GRID INTEGRATION SYSTEMS SEGIS Online Available http www1 eere energy gov solar pdfs segis concept paper pdf Online Available http w3 usa siemens com us internet dms btlv residential residential docs_Home SIE_BR_MicroinverterBrochure pdf Siemens Siemens Microinverter System Online Available http www sma de en products monitoring systems sunny beam with bluetooth wireless technology html Technical Data 9226 Blue Sky Energy What is Maximum Power Point Tracking MPPT and How Does it Work Online Available http www
15. OSFETs and IGBT which also have turn off loses and higher leakage or tail current associated with them Among the different types of optocouplers only the Darlington had an output voltage of at close to 360V which would comply with the maximum string voltage output given the 40 safety margin from the absolute maximum of 600V Given this criteria the only optocouplers that were fit for this application were the CPC1302 and CPC1301 This type of solid state relay had the highest output voltage of 350V and the 1302 model was chosen to minimize cost as it had the lowest price per channel 48 Value Analysis For the switch selector Google in conjunction with mouser was used to acquire a list of decoders that met my operating voltage and output requirement so I choose the least expensive Through hole option which was the CD4514B As for the chip selector I needed an active low decoder to enable the switch selectors and I already had a 3 to 8 decoder 74LS 138 at my disposal so for a proof of concept I decided to use it instead of looking for another decoder with low propagation delay Test results The Arduino Mega is designed to output in binary using its digital I Os any integer that can represented using eight bits That said two ports were used the first to set the chip selector and the second to set the switch selectors Unfortunately due to the delays team BEMANY experienced with the solar panels ordering the switches was delayed an
16. PT which can be considered as another type of monitoring system MPPT automatically alter the output of the panel to maximize its power output given data it has previously acquired from said panel 8 This data is the output current and output voltage of the panel which is acquired via current and voltage sensors There are two main current sensing methods resistive and magnetic based measurements In a resistive set up a small resistor is put in the path of power flow and the voltage drop across it is measured and converted to a current value Whereas in a magnetics based method a coil possibly an inductor a current transformer or a hall effect sensor is used to generate voltage induced by the magnetic field around a wire http www blueskyenergyinc com uploads pdf BSE What is MPPT pdf 13 As for voltage there are two types of voltmeters analog and digital Since the data needed to be acquired at a reasonable rate and transmitted wirelessly only digital voltmeters were reviewed All digital voltmeters consist of an attenuator to scale the voltage down to an appropriate range an analog to digital ADC converter and some sort of microcontroller that is programmed to interpret the signal from the ADC and output the appropriate code that is then converted into what is seen on an LCD screen Thus the measuring method used by a DMM relies heavily on the type of ADC D Digital Multimeters DMM DMMs have various different type of which
17. ands such as GE Maytag Siemens Samsung kitchen aid Bosch Each appliance was chosen based on their respective requirements set by the competition coordinators To determine the best appliances for the competition the respective energy consumption per competition day excluding standby power of the appliances that were complaint with the Solar Decathlon 2013 restriction was calculated For further detail please to the specific appliance of interest Refrigerator How much energy a refrigerator uses is heavily dependent on its size Therefore the smallest refrigerator that passed the sizing requirement set forth by the competition coordinator was 29 chosen that being the Sunfrost RF12 which uses 171 kWh per year 918 53 Wh per competition day Cooking When it comes to cooking appliances there are a few options Some homes have a range others have a cooktop and a separate oven and some do not have an oven at all Seeing how an oven was not needed for any of the contest during the competition period a 30 inch induction cooktop and a microwave with convection oven feature were chosen An induction cooktop was chosen because it is safer quicker and uses a lot less energy than conventional cooktops Induction cooktop top induce a magnetic field which creates Eddy currents in the metal pot thus heating the pot directly Conventional cooktop rely on resistive heating and heat diffusion which is altogether a slower heating process Becaus
18. arent power was used in equation 4 thus resulting in a system size of 7 1 kW peak for an inverter with a power factor of 0 95 34 4 System size DC System size AC invertor s power factor efficiency C Energy and cost analysis The average cost of PV system 5 5 per Watt 7 Should all the appliance had been chosen from in company in this case GE the size of the entire system would be 8 53 kW which would result in a system cost of 46 915 which is 9 130 more than the minimum size determine with the most energy efficient appliances 3 1 3 Panels The different types of solar cells on the market that were considered were monocrystalline Polycrystalline and amorphous Monocrystalline being the most efficient and amorphous being the cheapest but also least efficient For these reason the types that were considered polycrystalline and monocrystalline Within those cell types the one of the non standard panel types that was considered was bi facial solar panels This was considered because the house has an atrium which has a raised ceiling This raised ceiling is supported by a frame that is closed off with double pane low E glazed glass windows In my design these glass windows would be replaced by the bifacial solar panels so that some of the power used during the night would be recuperated A Constraints The area reserved for the solar panels was limited to 63 96 m so the panels were chosen based on efficiency Highe
19. at had the minimum energy usage and water usage per wash cycle was the Asko D5894XXLFI with 891 32 Wh per wash cycle Home Entertainment system As required by the competitions home entertainment contest 9 a television and a computer were required To satisfy the occupants of the house a sound system was also included in the list an appliances needed However we decided to integrate the sound system with the television Since the television would be displaying the PV array s performance a list of Smart LED TV with internet capabilities with a minimum size of 36 inches was made An LED television is more efficient than plasma TVs The list of LED smart TVs was narrowed down based on the energy used sound level and size prioritized in that order Based on these requirements a value analysis was performed and the top two television sets were Samsung SMART 6300 and 6000 which according the calculation use 337 Wh per day As for the computer needed a desktop replacement laptop was chosen because laptops use less energy than a desktop and based on the specification of the memory hard drive motherboard and graphics card installed a desktop replacement laptop can be as powerful if not more powerful than a desktop for less energy used per year 31 Washer and dryer Much like the dishwasher a washer was needed and one was chosen based on water usage and energy used per wash The clothes washer contest required us to wash 6 loads durin
20. bed As an embedded Linux system the Google manipulation program that was originally written to load the DMM s output into an excel file could be used here because the Rascal Micro is compatible with Python Value Analysis Support e Tutorial and examples that accomplished exactly what I intended to do 2 e Tutorials and examples that accomplished the building block of what intended to do 1 e No support O Weight Price Score e SD card bonus 5 e S0 537 5 4 e Price 4 e 38 5 75 3 e Support 3 e 75 5 112 5 2 e Area 2 e 112 5 150 1 e Additional task 1 e 150 0 e Additional component 1 Area Score e 10cm 19 9 cm 4 e 20cm 29 9 cm 3 e 30cm 39 9 cm 2 e 40cm 49 9 cm 1 e 50cm 0 Additional component This score was equivalent to the number of additional components needed to get the microcontroller working 55 ECE Aspects of Zero Energy House Additional Task In order to get a fully functioning server I would need to setup Ethernet and serial communication setup the website and then program the interaction between the website and the microcontroller This score was equivalent to the remaining number of tasks that I needed to do in order to get a fully functioning product Table 4 Server development board design options and scores price additional additional Bonus tor Dev Board area support price score components task Features mbed 13 52 2 59
21. between the DMM and the Server which controls it while the power block system provides enough power to the measurement and the Communication system 40 Boost convertor Rechargeable Battery d Input Block Regulator Ref Voltage Wireless Transceiver Worcester Polytechnic Institute Figure 3 7 DMM Functional system diagram The most important blocks were built first and then other features were added through iteration starting with setting up wireless communication between the DMM and my computer This allowed me to troubleshoot everything by printing error messages using the wireless transceivers Then a setup function was written which the user would go through to configure their system To be statistically significant this initial setup would set how many times each panel circuit branch and panel string current would be measured A Measurement block As illustrated in blue in the functional system diagram shown previously the measurement block consists of a microcontroller the external ADC and the switching network The switching network consists of solid state voltage controlled switches that connect the DMM s voltage attenuator to the solar panels The switches are turned on by the series of Decoders controlled by the microcontroller that is acting as the DMM s processing unit ADC Most microcontrollers have a built in ADC which is generally 10 bits Unfortunately this would not meet the leve
22. blueskyenergyinc com uploads pdf BSE What is MPPT pdf 66 ECE Aspects of Zero Energy House 10 H S Kalsi Digital Voltmeters in Electronic Instrumentation 2nd ed New Delhi India Tata McGraw Hill Publishing Company 1995 ch 5 pp 114 129 11 Walt Kester 2005 June Which ADC Architecture Is Right for Your Application Online Available http www analog com library analogDialogue archives 39 06 architecture pdf 12 Jaymi Heimbuch October 2 2008 Black amp Decker Launches Energy Saver Series Tools Online Available http www treehugger com gadgets black decker launches energy saver series tools html 13 Power2Save ENERGY MONITORS Online Available http www power2save ca products energy monitors 14 Diykyoto wattsonSOLAR Plus Online Available http www diykyoto com uk aboutus wattson solar plus 15 PowerSave Inc Energy Monitoring Hardware Online Available http www currentcost net monitor html 16 Boston Solar Company Costs of a Solar Photovoltaic System Online Available http bostonsolar us costs solar photovoltaic 67
23. can save up to 24 months worth of history depending on the transmission time the user sets and automatically updates the tariff 21 For instance this allows the user to decide when is the best time to do laundry depending on when it is least expensive to do so The system can connect to a computer to examine trends When the Home Hub is included it connects to a router and uses ENGAGE web portal for extended remote monitoring from any web enabled devices Unfortunately the Transmitter and Display unit are battery powered and do not have a battery monitoring feature that alerts the user to change the battery and the Hub is power using an AC Adapter 12 3 http www power2save ca products energy monitors 18 Figure 2 5 Power2Save ELITE model C Wattson Solar Plus This is perhaps the most popular energy management system This version of this Whole Home solution monitors electricity consumption and generation on the same unit Like the Power2Save option the sensor s clip onto a wire and the transmitter s transmission time is variable It has a 1 1 ratio between transmission time and how many months the battery that power the transmitter will last Again the wireless link between transmitter and display allows the display to show kWh carbon foot print and cost per year in multiple currencies This display has position sensitive display modes and glows according to the level of energy production and consumption s illustrated in figu
24. charging the battery 2 2 5 Oasis summary part II Overall all the consumption monitoring systems on the market consist of three major blocks that interact wirelessly for the most part These are sensors that measure current a monitor to process the data gathered by the sensors and a portable display To analyze the acquired data the monitors or displays need to be connected to a computer Systems like Power Save and Agilewave not mentioned previously have a separate block dedicated to enabling web based monitoring and data analysis The lacking feature in the aforementioned systems lie in the way they are powered and maintained Dependence on an AC adapter is tolerable for customers given that the power consumed is less than 5 Watts however to ensure that this dependence will not hinder Team BEMANY s chances of winning the energy balance contest Oasis will not depend on an AC adapter Oasis is a modular Whole Home product that monitors consumption and production using two units a DMM and a server The high sensitivity sensor s in the DMM would also clip onto a wire making it compatible with a single phase and three phase system and ensure high resolution measurements The DMM monitors its battery and alerts the user once it needs to be recharged In addition to acting as a charging station for the DMM s battery the Server processes all of the information using the data the DMM has transmitted This Server connects to any Ethernet port and
25. clock register I proceeded to measure multiple inputs parsed by the Arduino and again the resolution decreased back to 2 2 digit Thus I decided to leave it up to the Server to parse the data Furthermore the total current draw of each component and the entire circuit when powered using a bench top power supply and a bench top DMM The ADC drew 4 uA XBee and microcontroller drew 0 1uA on standby and 22 8 uA when transmitting The total current was 1 6 mA idling and 1 7 mA receiving For the final circuit configuration please refer to Appendix D 2 DMM B Input block The input block consists of three major components an attenuator a switching network and sensors to measure current Controlling the switching network was done using output pins from the DMM s microcontroller The command to switch to another panel was automatically administered after all the measurements for a given panel were taken Each measurement was initiated by the Server Attenuator The attenuator consisted of a voltage divider followed by a unity gain buffer using a single supply op amp namely the TLV2760 This op amp was chosen because it was the least expensive op amp available that could accomplish this A potentiometer was be used to account 46 for the tolerances in the resistors The unity gain buffer is needed to supply the ADC s channel with the input current it needs without drawing any current from the PV panels Simulation As you can see in
26. controller I focused on a few physical characteristics I needed an easily programmable microcontroller with at the very least 3 general purpose I O pins two for resetting the peripherals when needed one to monitor the battery of the DMM for the control system and simultaneous measuring a SPI interface to communicate with my external ADC a 2 pin UART port to communicate with my XBee module low current draw so that the battery s 42 required capacity would be held at a minimum and a few interrupts to facilitate troubleshooting all for less than 100 The Arduino family was chosen because it has exceptionally small learning curve associated with making it very easy to program Fortunately an Arduino MEGA 2560 was donated Test results As proof of concept initially I used the onboard 10 bit ADC the Arduino MEGA had and streamed the output using the XBee and X CTU The voltage was swept from zero to five volts and back down using a linear potentiometer and the input was read from pin AO using Arduino s Analog read example The readings had a 2 digit resolution so I concluded that the 8 bit Atmega2560 microcontroller was not enough to parse the acquired code Next was the implementation of the external ADC Following the SPI skeleton used in Arduino s Barometric Pressure Sensor example the serial clock polarity and phase were set to 0 As for the wiring the input and outputs were connected properly and the ADC s clock input
27. cscessesaeaesececsesesauaeaeceeesesseseasaneeeeens 20 Figure 2 7 POWERSAVE energy monitoring applications ccccccccccecsssessaecececesseseaeaeeeeecessessneaeeeeeens 20 Figure 3 1 Plumbing Distribution Drawing 27 Figure 3 2 Hot water one line dagram sssetiieesinestunestnnsi tienenia orietan ae eaa iie naika aiiai 28 Figure 3 3 SECUSOL Hot water appliance o occcccnccononoononcnnnnnnononnnnnnonnnnnnnnnnnnnnnnnnnnnnnnonnnnnnnnnnnnnnnnnnnnnnnnnnnns 29 Figure EES ege UE 33 Figure 3 5 PV array distribution drawing nn nnnnnnnnnnnnnennnnnnnnnnens 36 Figure 3 6 Echotestresulii ii 40 Figure 3 7 DMM Functional system diagram 41 Figure 3 8 Writing timing diagram EEN 45 Figure 3 9 Accessing the cockregister nn nnnnnnnnnnnnnn nn ennnnnnnnns 45 Figure 3 10 Setting the clock register to x hb nono nnnnnnnnnnnnnnnnnnnnnnnns 45 Figure 3 11 Reading timing diagram EEN 46 Figure 3 12 Reading the clock register eoret aeni depo er iiaeeeaino eE ERSE ENES 46 Figure 3 13 Attenuator test at maximum Input 47 Figure 3 14 Attenuator test CIR 47 Figur 3 15 Attenuator t st at 25 E 47 Figure 3 16 Hall effect sensor test setup nn rnnnnnnnnnnnnrnnnnnnnnnnens 50 Figure 3 17 As Built DMM revision le 53 Figure 5 1 BD connector 3 5 mm ptch nn nn nono nncnnnnannnnnn 62 Acknowledgment Prof Looft for letting the department know about the Solar Decathlon Prof Van Dessel for putting me on the Solar Decathlon team Ali Magzari for beli
28. d the rest of the system continued developing As a result the budget was exceeded and I was not able to get the switches I desired That said I used N channel MOSFET within three CD4007 that I already had at my disposal As for the remaining outputs of the switch selectors they were connected to red LEDs to indicate which pin was active Due to the dynamic nature of the switching network a video of the switching network working was taken Please refer to the link in the Appendix A 2 for the link and Appendix D 2 for the circuit diagram Sensors Existing consumption monitoring systems use clip on sensor which make it very easy and quick to install These clips are essentially current transformer or hall effect sensors capable of handling up to 200 Amps and 600V which is perfect for most houses since the main input power cable goes through a 200 Amp circuit breaker Given these technical requirements I looked at 49 hall effect sensors from Allegro Microsystems that meet my technical requirements contacted them and requested 35 A136LKTTN T linear sensors which they provided Test results The sensors were tested given their default setup indicated in the datasheet shown in figure 3 16 where the load capacitance was 10nF and filter capacitor was 1nF VCC VOUT A136x FILTER CBypass 0 1 pF CFILTER Figure 3 16 Hall effect sensor test setup The circuit branch was simulated using the power cable of my laptop The outp
29. directional wattmeter In addition to being a web based remote monitoring system it has variable resolution levels Due to uncertainties associated with the implementation phase of PV array Oasis is designed to adapt and fit most residential PV system Like Sunny Boy the DMM has a wireless communication feature that is secure In the Enphase system used by Siemens a computer acts as the server which communicates with the router This is requires for the computer to be constantly operating which would hinder team BEMANY s chances at winning the energy balance contest Thus Oasis followed Sunny Boy s example in having a stand alone server which logs the data and handles uploading said data to the webpage Other features such as system diagnosis and battery monitoring were also implemented to assure convenience All the aforementioned systems depended on the inverter s to log the performance data of the PV array Enphase relies on micro invertors which is favorable Having multiple small inverter allows the user to monitor each panel s performance and it reduces installation time and in turn installation cost This also eliminates the risk of the entire going offline should the inverter fail however each micro invertor is approximately 240 and for an array of 30 panels which is common for grid tied domestic systems the cost of monitoring jumps to over 7200 In the sunny Boy system the monitoring resolution is a bit less depending on how panels
30. ditioning HVAC equipment Also passive cooling methods were explored because the HVAC system can consume over 49 of the net energy used 1 1 2 Energy Management Once again to fulfill the zero energy requirement of Solatrium this major qualifying project also aimed to design build and implement a complete stand alone zero energy house monitoring system which consisted of three main subsystems the monitoring subsystem a website to serve as the user friendly interface and a server that would control the monitoring subsystem and relay the information provided by it to the user interface The monitoring subsystem consisted of a switching network and wireless digital multimeter DMM with a 0 01 V resolution and a minimum wireless range of 10m The switching network was controlled by the microcontroller which served as the heart of the DMM and would connect the DMM to a specific panel so that the DMM can measure the output voltage and then send the data to the Server Said server would then process the data it received and upload to a website This website would not only serve as the house s energy report card but it would allow the customer to track the performance to the PV array through any web enabled devices 2 Marketing Monitoring photovoltaic PV systems has been a necessity since the 1970 s when solar cells were first integrated with crucial systems such as power navigation warning lights horns on many offshore gas and oil rigs
31. e and difficult to install A Black amp Decker This Whole Home system has three major components that are independent of each other the weather proof sensor that attaches to the meter automatic light switches that detect the occupancy of a room via passive infrared sensors and a portable display shown in figure 2 4 The sensor wirelessly communicates with the portable display panel and takes real time measurements in kilowatt hours kWh and dollars 2 Customer reviews have reported that it was very easy to setup however because it is a Whole Home solution it doesn t provide enough information According to another customer review the measuring resolution was too high the 11 A http www treehugger com gadgets black decker launches energy saver series tools html 17 update rate was too slow and the data cannot be analyzed Also the display is battery operated but needed to be replaced every 10 weeks Figure 2 4 Black amp Decker Energy monitoring B Power2Save E2 ELITE and Home Hub energy monitors This family of Whole Home monitoring systems also consists of a sensor that clips onto a cable a transmitter and a display hub that is portable or can mounted to a wall The sensor relays data to the transmitter which is located near the load center The transmitter then sends the data wirelessly to the display shown in figure 2 5 which reports kWh carbon foot print and cost per year This system is attractive because it
32. e appliances their rated power was multiplied by a ninth of their respective total operating time The hot water system and all the appliances were calculated to use 0 34 kWh and 16 04 kWh respectively which resulted in 25 35 kWh used total per competition day B Insolation Since goal of the energy balance contest is to have a net energy used to be zero the energy used represents the minimum amount of energy produced The targeted energy produced is 140 of the energy used the extra 40 being a safety factor to account for system resistance dust shading and other unpredictable factors To convert this minimum energy produced kWh to a system size kW we must use the solar irradiance or insolation Insolation is a measure of solar energy or solar radiation on a given surface area expressed in mega joules per square meter MJ m2 or watt hours per square meter Wh m2 As you can see in equation 3 the units do not result in kilowatts Thus Wh m2 needs to be converted to hours namely sun hours 3 System size AC Energy used 1 safety factor insolation where the safety factor is expressed as a decimal Sun hour is another method of representing insolation where 1 sun hour 1 kWh kWp is equal to I kWh m Datong s average insolation is 5 26 kWh m or 5 26 Sun hours so the system needs to be 6 75 kVA To convert this apparent power to real power the inverter s power factor power factor being the ratio of real power and app
33. e induction cooktops heat the container they operate for a less time hence use less energy and the cooktop top does not remain hot after being used which makes it safer The cooktop of choice was a Kitchen Aid KICUS00XSS because it the better option given energy consumption and price In case the occupant of the house decides to cook a dish which requires an oven a microwave with a convection oven feature was chosen This would eliminate the need for an oven The convection feature was crucial because convection ovens are more efficient and cook food faster and better than conventional ovens This is because the hot air inside of them is actively circulated by a fan making the heat transfer from the air to the food more even and faster than in a conventional oven where the hot air relies on diffusion Dishwasher A dishwasher was required for one of the contest during the competition period Contest 8 5 required team BEMANY to washer a total of 30 place settings In the interest of minimizing the 30 operating time of the dishwasher the size of the dishwasher was restricted so that as many place settings as possible would be washed at once Thus the minimum required place setting was determined to be 15 which would result in the dishwasher being active only twice The list of the dishwashers that met this minimum place setting requirement was further narrowed down by total energy per wash and gallons of water used per wash The dishwasher th
34. easurement settings menu using the 4Display screen to acquire the measurement parameters should they not exist After each measurement parameter is entered that value would be transmitted to the DMM which in turn would send a confirmation message to move onto the next parameter Upon completion the Server would check for internet connection and display Please connect me to an Ethernet port as well as a graphical representation of the aforementioned message Once internet connection has been established the status of the system would be displayed This status would include battery conditions DMM connection internet connection and current net energy used The text of the net energy used would occupy as much 63 ECE Aspects of Zero Energy House of the screen as possible and be colored green if it is greater than 10 kWh white if it is positive but less than 10 kWh orange if it is negative but greater than 10 kWh or red if it is less than 10 kWh Text message alert would be included and configurable through the webpage or the display screen Utilizing this feature would be controlled through an interrupt of which the service routine would be sending a text message through Google and indicating the error and if it was automatically resolved and that a confirmation message needs to be sent back as per the restriction set by Google On the webpage the existing page that streams output of the Rascal s onboard ADCs would be u
35. eling were http www1 eere energy gov solar pdfs solar timeline pdf http eetd Ibl gov ea emp reports Ibnl 4121e pdf http www masscec com index cfm cdid 11663 pid 11150 http www irena org DocumentDownloads Publications RE Technologies Cost Analysis SOLAR PV pdf http www1 eere energy gov solar pdfs segis concept paper pdf 10 included This would allow the user to easily detect issues such as unusual power consumption or production loss For convenience Oasis was web based so that the user could detect the previously mentioned abnormalities from any web enabled devices making Oasis very easy to use and integrate with the market 2 1 Existing Monitoring System Existing monitoring system differ in reporting and data acquisition methods Remote systems report their data remotely through the web or Bluetooth which is extremely convenient for the user The data acquisition method of choice does vary depending on the desired level of information The simplest most inexpensive monitoring systems gathers information on the system level meaning the total output of photovoltaic PV array s performance and the total energy consumed throughout the house would be reported and recorded making it least informative approach Some production monitoring systems provide string level accuracy where each individual panel s performance is monitored for maximum level of information The same is true for consumption monitoring s
36. es the PV system and the loads used in the house for the competition This PV system is significantly different from than the systems originally designed and specified previously because all of the electrical loads were donated to team BEMANY 4 1 PV system The approach to the PV system sizing changed from using what is needed to using the worst case scenario Thus an 11 6 kW system will be implemented in compliance with the inverter This decision will assure that Solatrium does have a positive net energy usage however the price of the solar panels which were 40 monocrystalline 290 W panels from 1SOLTECH s reflection series may be taken into account for the price of the house which is already over the targeted 250 000 This could be detrimental to the market appeal contest scores Inverter was an SMA Tripower 12000TL central three phase invertor This was chosen among the option available for donation because the size the PV system was no longer a concern This decision was made without any of my input and I was not notified 4 1 1 Passive house design changes Due to the low R value of the bifacial solar panels and construction issues that would arise from using these panels as a replacement for the glass of the Atrium frame this suggestion was rejected Also the green roof was rejected due to the financial and transportation complications it would bring 59 ECE Aspects of Zero Energy House 4 1 2 Load calculation The appliances
37. es with at least 1000 mAh were considered and the cheapest option was chosen that being a 1400 mAh Li Po 56 ECE Aspects of Zero Energy House PoE Module Power over Ethernet is a system that allows data and power to be transmitted through the same Ethernet cable by transmitting 48 V through the unused wires within said Ethernet cable The PoE module was restricted to have a SV output however this model was not available through any of the distributor supported by the department so a 9V module was ordered instead Unfortunately the distributor s stock was depleted before the order was put in so a 12V module was sent instead Thankfully the PoE modules can be adjusted to a lower or higher output voltage so this 12V module was configured to 9V output Since the battery charger has a SV input a buck converter was implemented to resolve this mismatch Buck converter A buck converter is a DC DC converter that reduces the output voltage but increases the current by storing some of the current induced by the input voltage in a magnetic field and releasing it when the input voltage is removed Of the high efficiency converters available from Digikey only the options with an output current of at least 1 A were considered Given this requirement the least expensive choice was the MCP16323 Test results Since the MCP16323 was a quad flat no lead package a printed circuit board was undeniably necessary to move forward That said the PCB
38. esult in 0 1 W resolution for both production monitoring and for consumption monitoring 2 2 4 Power Block As mentioned earlier Oasis needed to be a stand alone system to ensure that team BEMANY use only the energy that they need to use per competition regulations However an AC adaptor must also be included to power the system in case the competition coordinator do not allow a battery with a capacity as high as what is needed or if the battery were to malfunction This redundancy will allow the user to plug the system into an outlet and still be able to monitor their PV array As a mainly battery operated system Oasis must have small power consumption Given the limited capacity on the battery set by the Solar Decathlon the system needed a low power mode where the DMM and the Server would sleep an hour after the last zero voltage measurement and wakes up six hours later the sun rises These requirements constrained the system to have power characteristics similar to a handheld device The case for the DMM s battery must be insulated and sealed completely to reduce the battery s performance dependence on temperature and easily accessible The battery itself should 23 have a capacity high enough that can run the device for at least three months without recharging As for the charging circuit in the Server it will be designed so that in at most four hours it can fully charge the battery from a 70 discharge without over
39. eving that I could do more Prof Emanuel for his advice on the switching network Prof McNeil for daring me to finish by D term Joe from the RBE department for letting me borrow his XBee modules during the first semester Tom for his advice on choosing manufacturers Rascal Micro Allegro Microsystems and Prof El Korchi for sponsoring Adam Vadala Roth for being my consultant for my PCB design and Altium instructor My Brothers from APO who answered to my call when the CS portion came knocking Dan Miller for helping me with Python Ben Leone for teaching me how to use Linux Nick DeMarinis for proof reading my SPI connection and teaching me how to troubleshoot it when I started to doubt everything Prof Jarvis for advising but mostly for encouraging and believing in me when I started to doubt myself and always being helpful no matter what the question was and for pushing me and daring me to be awesome Abstract The goal of this MQP was to design and implement a photovoltaic PV system and Oasis a stand alone web based bidirectional wattmeter to aid Team BEMANY of the Solar Decathlon China 2013 competition in meeting their goal in implementing a zero energy house To achieve this goal a wireless digital multimeter with an accuracy of 0 1 with a minimum wireless range of 10m was created to monitor the voltage of the individual panels of the PV array and it relayed the data to a microcontroller based server This server would then communicate with a
40. g the entire competition period each load consisting of 6 bath towels which resulted in a total weight of approximately 13 Ibs Since front loaders use less energy than top loaders and in the interest of minimizing the how many wash cycles is needed to win this contest a list of front load washers with a minimum loading weight of 10 pounds was created and narrowed down to the washer that used the least amount of energy given their power and active time Also since condensation dryers do not need a vent and use less energy than conventional dryers a second list of condensation type dryers with a minimum loading weight of 10 pounds was also created and narrowed down to the dryers that used the least amount of energy given their power and active time In the interest of using less space since the house s technical room is small 1 9 x 2 199 m we also explored washers with a condensation dryer function and we found that the most efficient option is a 2 in 1 washer dryer The total energy consumption per competition day for this module was 4 48 kWh per competition day Lighting All the lighting fixtures were chosen based by Briana Weisgerber from a few companies that agreed to sponsor team BEMANY The fixtures were restricted to LEDs and of her choices total energy consumption of all the lighting fixtures provided that they remain on for approximately 3 hours per night resulted to 0 95 kWh per competition day C Passive house design decision
41. igure 7 12 and measuring using the default values recommended by the datasheet only worked once as shown in Appendix A figure 7 11 I tried reverting back to older versions of my code but to no avail once again the data ready pin stopped indicating that the conversion was complete So reading the data ready bit was done instead and results were acquired I repeated the test but it became clear that soft polling by itself was not reliable because the expected 2V was measured as OV So I used soft polling and measured the data ready pin but again the pin was not indicating that the data was ready to be read The same outcome was seen with a different ADC so I then tried to manually pull the data ready pin low by connecting it to ground and the code continued to the next step This indicated that the problem was not a wiring or a hardware problem Finally at a loss I contacted Maxim Integrated and spoke with a support technician who was equally puzzled by my issue He asked me to send him my code to revise it which I did Still I did not stop troubleshooting and with some help from one of my friends I was able to determine that the source of all my issues were typos and my SPI configuration While troubleshooting I accidently reverted back to an older version of my code where the clock polarity and the phase for the SPI clock were incorrect This was determined by using a four channel oscilloscope to view the timing diagram Once the SPI mode was reverted
42. is dependent on the ADC that is use gua Essentially there are two types of families of ADCs integrating and Non integrating which can be further broken down into three approaches or seven different implementations The first type applies the relationship between voltage and time This method is used by Ramp type Dual slope Integrating type DMM which measuring the amount of time that is needed to charge a capacitor at a constant current 9 Other integrating type DMM operate similarly but use the relationship between the input voltage and frequency as opposed to voltage and time TT The Non integrating type use a voltage matching approach where the input voltage is compared to an internal reference voltage and the LCD does not read a value until the input is equal to the reference voltage UI This approach is broken down into the following implementations Successive approximation registry SAR Continuous balance ADC Staircase and Sigma Delta 2 A ADC 10 Only the SAR and X A were considered because continuous balance and A D staircase are slower than other methods undependable accuracy susceptible to error due to noise amp 7 interference Also ADC Dual slope integrating type though extremely fast and accurate it is Electronic Instrumentation By H S Kalsi 14 meant for scientific grade measuring application where high accuracy is needed and thus is an over design for PV monitoring pA SAR ADC Successive approxima
43. ks result in a certain level of energy consumption This energy consumed is provided by a small village grid and ideally Solatrium the house designed by Team BEMANY the Belgium United States team consisting of Ghent University of Belgium Worcester Polytechnic Institute Polytechnic Institute of New York University would return to the grid as much energy as it consumed thus satisfying the requirement the energy balance contest In an effort to make Solatrium a zero energy house its photovoltaic PV system was designed and a complete web based monitoring system capable of monitoring PV production and domestic consumption was created The system was to be completed with a web based user interface that enabled the user to remotely access information about the PV system s performance however due to time constraints this was not implemented Future features include but are not limited to enabling override of the home automation system which controls the lighting and the heating ventilation and air conditioning HVAC system to ensure that the net energy used is at least zero 1 1 PV system Design The photovoltaic PV system was designed by determining the size of the array creating distribution plan deciding on the PV panel based on module efficiency their tilt angle and the invertor To minimize cost the smallest adequate PV array size was determined by choosing the most efficient appliances and heating ventilation and air con
44. l of accuracy that I want so an external ADC is needed Worst case 41 scenario the maximum voltage of the PV array would be measured and per UL regulations would be 600 V After attenuating this range to a manageable range of 0 2 5V a 10mV change in the original system need to be detectable thus a 1 bits must be equal to this 10mV attenuated which is 83 33uV per bit Log2 2 5 0 000083333 14 87 bits Thus a separate 16 bit ADC will be used to meet the level of accuracy of 0 1 error Value Analysis To be able to measure voltage and current simultaneously I needed an ADC with two channels operated with 5V at most and with at least 16 bits Of all the RoHS compliant multi channel 16 bit ADC shown below in the table 3 I choose the MX7705 because it had the least power consumption and was the only one with a through hole alternative which I choose to make prototyping easier The next revision of product however would have the surface mounted version or the ADS1208 to cut costs Table 3 External ADC design options ADC Type Sampling Rate Min Power mW Price Packaging AD7686BRMZ SAR 500 21 5 21 85 SMD ADS8325 SAR 100 4 5 10 013 SMD ADS8318 SAR 500 22 5 16 45 SMD BDGSRG4 SAR 500 22 5 19 51 SMD ADS1208 Sigma Delta 40 65 8 55 SMD AD7401A Sigma Delta 20000 93 5 SMD MX7705 Sigma Delta 38 4 1 12 87 Through Hole or SMD Microcontroller When choosing a micro
45. ld they need to without having to change the inverter 50 Hz output Single phase inverters were chosen because central inverter configuration is susceptible to reliability issues and the inverter could be configured for a three phase wye connection As you can see in the table 1 the Power One PVI 5000 had the highest efficiency therefore was chosen Table 1 Inverter list Inverter Max input Max AC out eff Fronius IG Plus 55 V 1 2 3 5 26 5 95 06 Sunny Boy 4000TL 4 2 4 95 24 Power one PVI 5000 TL OUTD 52 5 96 15 Kaco 5002 xi x 52 5 95 50 SolarMax 4000P 4 8 4 6 95 83 3 1 5 PV system sizing summary To minimize the amount of energy used throughout the competition the house was design to need minimal assistance from the HVAC system the most efficient appliances were chosen and each mechanical systems was designed to use the least amount of energy while maintaining their practicality As mentioned early the PV array will be a 7 2 kW array consisting of 22 monocrystalline panels from Sunpower s 327 E20 series The size of the array was chosen based on how much energy is used through the contest during the competition Datong s metrological information The total energy used by all the loads throughout the competition was calculated to be 170 98 kWh of which 3 08 kWh is consumed by the plumbing system 26 90 kWh is used by the HVAC system and the remaining 141 00 kWh is used by lighting and the app
46. liances 3 2 Oasis Energy Management System conceptual Design This complete web based monitoring system is capable of monitoring PV production monitoring and domestic consumption The system will consist of a switching network wireless digital multimeter with a maximum resolution of 10 mV resolution with a minimum wireless 37 range of 10 m and a server The DMM consist of an external ADC a voltage attenuator to scale down the panel s voltage to the ADC s range and a microcontroller that also acts as the controller for the switching network which connects the different panel s to the DMM s input Once measured the data is sent to the Server via a wireless module Said Server would then upload the data to a website which allows the user to monitoring their PV system Oasis was design with the intention of having the DMM next to the load center which was located near the PV combiner box The Server was to be placed behind a router or over an Ethernet port 3 2 1 Communication block DMM and the Server communicate wirelessly to each other To achieve this the communication block was crucial and the first block to function to be implemented The methods of wireless communication considered were Bluetooth because it is robust low power and low cost Wi Fi 802 11a and XBee RF modules The Wi Fi module was immediately eliminated because higher frequencies also have high power demands associated with them despite the fact that highe
47. lot of support and examples that accomplished exactly what was desired make a server using a microcontroller It also had a pre set Ethernet port but purchasing and configuring the Ethernet port in addition to setting up XBee Serial communication with the DMM creating a webpage and programming the interactions between the mbed and the webpage were additional mandatory tasks From Sparkfun I found the Ethernet Web PIC Development Board This was slightly cheaper than the mbed but it was had little support in comparison and this option had parallel connector which was going to make it difficult to attach a PoE module Next was the Spinneret Web Server from Parralax which had an SD card slot included and Ethernet port already setup This option also required an additional Prop plug making it the most second most expensive option with as much support as the PIC Development Board The mbed was the most attractive option despite the fact that I would need to setup the RJ45 socket By consulting with a friend of mine who had worked a lot with Ethernet the Rascal 54 micro was recommended to me This option also had a built in SD card slot and an Ethernet port In addition this board is programmed in Python through Ethernet it was designed to be a web server It included a web server editor and a webpage that by default streams the input voltages of its ADCs This was very attractive to me despite the fact that it cost three times more than the m
48. m which encompassed many concentrations within the electrical and computer engineering such as wireless communication power systems embedded systems as well as skills from other disciplines namely 3D modeling systems programming and web development through HTML and JavaScript Oasis though incomplete due to time constraints would have had the ability to monitor and energy produced by a photovoltaic array and the energy consumed within a medium sized home approx 1500 sq ft Oasis was designed to have the highest level of accuracy by implementing per panel voltage reading and string level current measurements for production monitoring For consumption monitoring the current measurements would have been taken per circuit branch 5 1 DMM Optimization In the end the DMM was capable of measuring voltage because the ring concentrators for the hall effect sensors were not acquired due to financial constraints As it stands now a program could be written to automatically configure putty to read the incoming data from the DMM through a COM port and save it as an excel sheet Following this step said program would run a python code which was written to upload and download files from a directory into the users Google drive account see Appendix C for details Many existing blocks still need to be revised for Oasis to be considered market ready For instances cost could be reduced by removing the level converter that was used in conjunction with
49. mation found through NASA a PV array consisting of 22 monocrystalline 327 W panels from Sunpower was designed However due to uncertainties associated with the donor for the solar panels a list of other potential panel was made shown in Appendix B table 8 1 25 3 1 1 Load calculations A Mechanical Load calculations The mechanical loads of the house primarily come from two systems The heating ventilation and air conditioning HVAC system and the Plumbing system The design of the HVAC system was extremely crucial because given a low Seasonal Energy Efficiency Ratio SEER value can consumes over 49 of the energy used for in a medium size home like Solatrium HVAC The HVAC system that was designed to be as efficient as possible so given the size of the house and the building material a mini split ductless system was necessary Professor Van Dessel calculated that a 2 5 ton system was need and with some help from Johnson Controls this number was confirmed To calculate exactly how much power the system would use a thermal analysis of the house was done through Ecotect which is a sustainable building design tool which is capable of simulating and analyzing a building s energy performance given its environment Using this it was predicted that the HVAC system would consume 235 kWh for heating and 221 kWh for cooling for the course of ten days given a coefficient of performance COP of 1 Thankfully Johnson controls was able t
50. o donate a mini split ductless HVAC with a SEER value of 23 which is equivalent to COP of 6 741 This means that this system is capable of meeting the thermal needs while using 14 84 of the power needed from a system with a COP of 1 To evenly cool the house a modules was placed in each of the bed rooms and two equidistant from the center of the Atrium Plumbing The plumbing system consists of two sub systems the domestic water and the fire suppression system To minimize installation times piping and hot water wait time a mix of a 26 trunk and branch system and a remote manifold system was designed see figure 3 1 To minimize installation time and how much piping was needed cross linked polyethylene PEX pipes were chosen for both subsystems because of their flexibility Colector Figure 3 1 Plumbing Distribution Drawing Strictly for the domestic water the source of the hot water plausible for the competition given the size of the technical room 1 9 x 2 199 m the energy used and that the water will be provided municipally include Hybrid water heater Instant hot water dispenser Point of Use Centralized hot water a k a direct hot water and solar hot water Given that a solar hot water 27 could become unreliable during the winter but an instant hot water dispenser would use too much energy during the winter both approaches were included in the design Solar Collector Hot Water Figure
51. ors network and upload it to the website These blocks will interact wirelessly as well and be battery powered to ensure that Oasis presence does not affect the performance of Solatrium The DMM must have battery monitoring feature and alert the user to swap the battery of the Server with the DMM The Server must be powered through the Ethernet port and act as a 21 charging station for the DMM s battery It must also comprise of a microcontroller capable of serving as the control center of Oasis and process the data received to provide information in terms of energy cost and carbon foot print as well as predict weekly overall consumption so that team BEMANY is aware of its odds of winning the energy balance contest It will serve as the central controller for the entire Oasis and serve as a backup data storage space for the system All of the data must be logged daily and stored on an SD card for long term monitoring This would allow the user to analyze their energy spending habits without interrupting the system and increase the amount of data that can be stored 2 2 1 Communication Block Technical Requirements The communication circuit as mentioned earlier in this chapter was restricted to primarily wireless with a range of at least 10 m while minimizing the power required To incorporate real time communication the output data rate was the highest standard rate maximum rate that yielded no losses in packets 2 2 2 Input Block Requi
52. r frequencies are less likely to experience interference This relationship between power and frequency explained why the power required was at least 8 times higher than Bluetooth Thus out of the remaining two options the best modules from each family given the technical requirements were the RN 42 Bluetooth 2 1 2 0 1 2 1 1 and the XBee ZB Technical requirements o Range 10 60 m which is enough to reach the modem which will upload to the web Data Rate 4800 bps I Mbps O o Maximum Linear Power density lt 5 mW per meter o Power lt 150mW 38 A Value Analysis criteria To compare the two options power was the only concern That said the option with the least power density was chosen therefore the BT PAN1720 was the better option but it was not available from any of the distributors supported by the ECE shop That said I ordered and used the next best option which as you can see from table 2 was the XBee ZB Table 2 Wireless Transceivers design options module Distance MAX Power op voltage Power Density XBee ZB 40 148 5 3 3 3 7125 XBee 802 15 4 30 165 3 3 5 5 XBEE Wi Fi 30 858 3 3 28 6 BT PAN1720 40 132 3 3 3 3 RN42 20 148 5 3 6 7 425 WT32 30 252 3 6 8 4 B Test results Before setting up the DMM XBee modules were tested using the Echo test mentioned in the user manual To do so using X CTU the modules were configured to have the same channel and the transmission speed by firs
53. r the efficiency the more watts area so panel with high efficiency won because it used less area 5 Module efficiency 10 Min power per square meter system size usable area e http bostonsolar us costs solar photovoltaic 35 To make sure that the panels are far apart enough to ease cleaning the most efficient solar panel on the market was chosen Figure 3 5 PV array distribution drawing As shown in figure 3 5 all of the panels were to be oriented completely flat on the roof per aesthetic limitations set by team BEMANY The mounting system was donated by Unirack who had agreed to sponsor the team before the panels were chosen The location of the panel was limited to certain area to avoid shadowing The exact locations of the shadow were rendered through Revit Architecture which is a building information modeling software that is capable of modeling a house and set geographic setting to anywhere on the planet for solar studies This feature was used to determine where the shadows from the atrium s frame would be 3 1 4 Inverter In the interest of maximizing efficiency only transformer less single phase solar invertor were considered for the design Of this type inverters capable of handling 4 5 kWp were chosen so that the largest PV array 12 kWp could be split somewhat evenly The crucial features and characteristics were efficiency MPPT which would enable team BEMANY to change the size of 36 the PV array shou
54. re 2 6 it can be connected to a computer to log daily consumption data and the entire system has does not have any Hazardous materials RoHS compliant The housing comes apart and is recyclable and as a bidirectional system it is inverter independent compatible with single and three phase and measures with 1W resolution H This is by far the closest system to Oasis however the transmitter is battery powered and the display must be plugged in 13 http www diykyoto com uk aboutus wattson solar plus 19 gt KS pw A Figure 2 6 Wattson SOLAR Plus setup D POWERSAVE energy monitoring This Whole Home monitoring system can be considered a hybrid because it is modular Multiple clip on sensors and transmitters can be used to expand from single phase to three phase monitor in addition to its plugin sensors which resemble the Kill A Watt The plugin sensors and clip on sensor s transmitters connect wirelessly to the display Hub or an internet gateway which can be connected to a web bridge This web bridge then connects to a router to enable web based monitoring The display again reports kilowatt hours kWh carbon foot print and cost per year but only in dollars ua ei 3 Solar Main Panel e D 2 J Generator Water Heater Refrigerator Server Figure 2 7 POWERSAVE energy monitoring applications 1 http www currentcost net monitor html 20 s you can see in figure 2 7 this system is very ve
55. rements The input block conditions the incoming panel voltage so that it can be processed by the measurement block Typically the input block of a DC voltmeter consists of a linear attenuator to reduce the incoming signal to a reasonable range This input block must scale down 600 V to the reference voltage needed by the measurement block and have a high input resistance so that little to no current is drawn from the device being measured 2 2 3 Measurement Block Requirements This version of Oasis measures DC voltage only thus is not compatible with system that uses micro inverters However the measurement block must measure individual panels as many times as the user desires This is to ensure that every reported measurement is accurate and statistically 22 significant The same will be done for current measurements in every branch of the house That said receptacles will be monitored by current branch as opposed to individually The voltage readings were constrained to 10 mV resolution and 0 1 accuracy The PV panel s current should have 100 mA resolution and 0 1 accuracy Like the panels current the current in each circuit of the house must be measured with a 100 mA resolution and 0 1 accuracy as many times as desired Thus the current sensors must be hall effect to limit complexity and make installation as safe and as easy as possible Additionally these sensors must have high sensitivity robust to temperature This would r
56. rnnnnnnnnnnnnnns 25 3 1 PV system A AER 25 3 1 1 LOA CalCUlAtiON Sesmero aaa 26 3 1 2 System calculations saa 33 3 1 3 A O 35 3 1 4 O 36 3 1 5 PV system SIZING SUIMIMANY EE 37 3 2 Oasis Energy Management System conceptual Design 37 3 2 1 Communicationiblo dk acorta 38 3 2 2 DM Mini ae EE voles 40 3 2 3 DMM Summary and design Changes cccccononoconnnnnononanononannnnnonnnnnnanonnnnnncnnnnnnnnnnnnnnnnnnnnnnnns 52 3 2 4 SENER 53 3 3 Server SUMMAN usage NS 58 4 PV system Design change 59 4 1 A E R TE E A E A A T a a 59 4 1 1 Passive house design changes 59 4 1 2 Bet ete OIE ar EEN 60 4 2 PV system design CONCIUSION rrrrnnnnrnrrrnrrnanannnnrnrrrnnsnanannnnrnnnrnssnsnnnnnnrnnnerssrannnnnnnnnnsssssaannnnnsnnssee 60 5 Qasis further development egen degt dida enn 61 5 1 DMM Optimi At ON EE 61 5 2 Server OptiMizatiO E 63 6 lee le Lu 66 La ele Die le Vee 68 TS soen a a a a e a a a a a a a a a 83 92 TAPPENdX Ture eee 86 al DE ele ne C2 msn een 93 Tl Appendix Delstatens eee 107 12 APPEAR eee 431 Table of Figures Figure 2 1 Enphase Enlighten Monitoring system 12 Figure 2 2 Sunny Beam hub EE 13 Figure 2 3 SAR ADC 4 bit decision three 15 Figure 2 4 Black amp Decker Energy monitoring rrrrnnnnrorvrrrrnnnnnnnnrnrvnnrrnrnnnnnnrnnnrnrsnsnnnnnnnnnnnnssnsnnnnnnrnnnsnssnnnnnn 18 Figure 2 5 Power2Save ELITE model 19 Figure 2 6 Wattson SOLAR Plus Setup cssccccccecessessnaeeececscesseseusecece
57. rsatile however the same deficiencies as the aforementioned systems apply The transmitter is battery powered but it does not have battery condition alerts and the Web Bridge plugs into the wall 2 2 Design Requirements The design requirements for Oasis are abundant therefore the specific requirements will be addressed in their appropriate section later in this chapter However the system as a whole must be dependable easy to install as maintenance free as possible inexpensive and invisible to the PV array In other words Oasis will need to be completely isolated from the PV array and the stand alone to ensure that its presence does not alter the performance of Solatrium the house built by the Solar Decathlon To assure dependability Oasis will be designed to be accurate fast versatile and robust Its accuracy must at least match the accuracy of a bench top digital multimeter DMM The measurements will be taken fast enough so that the website can display the PV array s performance in real time The DMM must be able to simultaneously measure each panel s output voltage and output current Given that Solatrium would most likely come back to Massachusetts Oasis must be New England proof or be primarily located indoors which would also increase its reliability and life span Like some existing products Oasis will also comprise of two hardware blocks a DMM and the Server that would process the data acquired by the DMM s sens
58. ry Single 3 7 V 6600mAh Supply AAA Voltage mi follower See STE M 1 240 gain XBee ZB Voltage Level converter divider XBee ZB Worcester Polytechnic Institute Figure 3 17 As Built DMM revision 1 3 2 4 Server The Server was mainly a microcontroller and a battery charger To avoid plugging into the wall to use AC power a Power over Ethernet module was also needed That said the microcontrollers mentioned in the following section were chosen with easy PoE integration in mind Rapid prototyping was also crucial because only eight weeks were left until the final product was due Thus development boards that cost at most 200 with built in Ethernet interface and an onboard PH Yceiver to manipulate the hardware for the send and receive commands of the Ethernet frame were targeted In addition to those restrictions only development boards with a 32 bit processor to parse the data coming from the DMM were considered Also size was a crucial issue because smaller development boards would be able to fit on an Ethernet port without blocking another port 53 PoE Module gt Battery E PoE ie e Li Po Battery Boost 3 7V Converter SV output DMM Figure 3 18 Server conceptual block diagram A Microcontroller Given the aforementioned technical requirements four development boards matched my criteria The first was the mbed NXP LPC1768 Given the information provided on its website it had a
59. sed as a template to create multiple pages that graph the output of each individual panel and current branch The measurements would be received by the Server through a function which would receive the incoming data average it subtract the previous average from it parse it then load it in an array shown below in table 6 The entire array would then be read one row at a time and graphed The graph would always append the new value Table 6 Server example array containing performance data Branch Branch Branch Branch time PanelO Panel 1 Panel x 1 Panel x 0 1 x 1 x 6 00 00 28 91 35 51 35 59 35 58 12 01 20 00 1 03 3 64 6 01 00 28 95 35 52 35 60 35 61 12 01 19 98 1 04 3 65 6 02 00 28 99 35 51 35 20 35 60 12 02 19 99 1 06 3 65 6 03 00 29 01 35 60 35 01 35 59 11 98 20 01 1 02 0 00 6 04 00 29 0 35 58 35 03 35 58 12 00 20 00 0 00 0 00 As for switching the battery before the text message alert is sent the Server would save all the present parameters and values This would make sure that the data would not be lost and that 64 ECE Aspects of Zero Energy House the system would automatically reconfigure and resume normal operation without any input from the user 65 ECE Aspects of Zero Energy House 6 Bibliography 1 2 3 4 5 6 7 8 9 lowa
60. sting Thus it would become a closed loop system so that the 5V output could be maintained despite the fluctuation in the battery s output voltages This could be done using the information the DMM s built in ADC gathers about the battery by monitoring the MX7705 s reference voltage however an analog 62 ECE Aspects of Zero Energy House approach would be better because it would be faster to implement As for the battery itself the capacity of the main battery should be doubled if feasible This would give the DMM 6 months of uninterrupted operations 5 2 Server Optimization Finally the Server should be finished Due to the time restriction and this crucial part of Oasis was not fully developed Connection between the Server and the DMM was the only step that was completed The remaining steps included acquiring the measurement parameters through the 4Display screen which was initially acquired to implement a display hub Given the remaining weeks this hub was abandoned and its directives namely displaying information and being the charging station for the battery were reassigned to the Server The screen on the Server would act as the local alert medium and as the local user interface when changing the battery or initializing Oasis for the first time Given more time the Server would have been programmed to automatically check the measuring parameters upon start up and connect to the DMM Following this it would go through the m
61. t reading the settings on one of the module changing the baud rate to 9600 bps then uploaded the settings After uploading was complete the XBee modules were swapped and the settings were written again Once complete the first XBee module was powered and the RX and TX pins were connected to each other and then in the terminal hello world was typed The terminal tab in X CTU is where incoming and outgoing data can be seen as ASCII characters As the test was typed each letter sent shown in figure 3 6 in blue was returned in red as expected This test was repeated without a level converter which were donated by a friend and failed In the interest of time the level converter was kept in the implementation of the DMM 39 About XModem PC Settings Range Test Terminal Modem Configuration Line des Asse Close Assemble Clear Show ETS co DSR DTR 2 ATS Y Break Com Packet A Hex KkkhheeTT Moo wwoorrildd COME 96008 N 1 FLOW NONE Rx 20 bytes Figure 3 6 Echo test results 3 2 2 DMM The DMM is based on four subsystems or blocks shown in figure 3 7 the previously designed Communication block measurement block Input block and power system The measurement block is essentially a digital voltmeter that controls the input block s switching network which essentially connected the individual voltage sources to the meter s input As for the Communication block it is the bridge
62. t was used Test results Initially the output voltage of the converter was 4 96V because I used the available part form the ECE shop As additional results the inductor dissipated a lot of heat Later the diode was replaced with suggested parts in the LT1111 s datasheet as well as the inductor with a power inductor rated for at most 0 5A Given this criteria I found three inductors from mouser of which I ordered and used the least expensive option the KMP 2700T The output voltage using this inductor was 4 9957 V As it is now the boost converter only functions properly when the battery s voltage is 3 7V Later revisions should implement a closed loop negative feedback feature that allows the boost converter to adjust the switching frequency so that the output stays 5V unless regardless of the output voltage of the battery 3 2 3 DMM Summary and design changes In short the DMM built had a 38u V resolution which corresponded to 9 155 mV resolution from the panel voltage using a 16 bit sigma delta ADC Controlling this ADC as well as the other peripherals is an Arduino mega 2560 This was chosen for its simplicity and favored for 52 directly outputting integers in binary code using the digital ports Altogether with the XBee ZB module and the level convertor the DMM draws at most 2 mA which given the battery used would a little over 2 months and a week LT1111CN8 5 Buck Boost IC SV output TLV2760 Li Po Batte
63. the figures 3 13 through 3 15 the voltage divider can be used to achieve the linear attenuation needed at the input of the DMM Figure 3 15 Attenuator test at 25V 47 Test results This circuit was extremely simple and worked on the first attempt It tested with 30V from a bench top power supply and ideally expected the measured the output to be 0 125V using the bench top DMM In actuality the power supply was set to 30 001V and the potentiometer was calibrated until the bench top DMM read 125 00 mV which was as close as I could get to the expected output of 125 004 mV The current through the resistor was measured to be 2 84 uA so assuming that he maximum measured voltage would be 600V the resulting current would be 56 8 uA which would correspond to a power dissipation of 33 9 mW Thus given a 20 safety margin on the current draw the resistors rated for at least 50 mW were used Switching network The switching network consists of three main parts The chip selector and the switch selectors which were implemented using decoders and the switches themselves The switch selectors were all giving the same input to minimize the number of digital I Os needed on the microcontroller development board while the chip selector would enable one of the switch selectors which would then turn on a specific switch The types of switches that were considered power MOSFETs optocouplers and IGBT Typically optocouplers have better isolation then M
64. tion register or S R is very accurate because the registry tries to efficiently match the input voltage to its reference voltage Instead of trying to match the input voltage starting from the lowest reference voltage value like in sequential search algorithm the registry implements a binary search algorithm starting with the most significant bit that could represent the internal reference voltage and works its way to the least significant bit as shown in figure 2 3 e III 1111 1110 1110 gt 1101 1101 gt 1100 1101 1011 1010 1100 1010 gt 1001 1001 1000 0111 MAA p0 1000 0110 0101 0101 0100 a 0011 0011 0010 0010 0100 gt 0001 0001 0000 Figure 2 3 SAR ADC 4 bit decision three 2 A ADC 2 A ADCs are the most popular type of ADC in bench top DMM They are analogous to operational amplifier configured as a current buffer in the sense that the input voltage is equal to the output given the rail to rail voltage except that the output is a digital string or bit stream whose average value is equal to the input voltage again given a certain range negative to positive reference voltage ES 10 http www analog com library analogDialogue archives 39 06 architecture pdf 15 E Oasis summary part I In summary the aforementioned design options have certain characteristics and features that make them extremely helpful in the development of Oasis the web based bi
65. upgrades amp diagnostics of the system components It typically consumed 2 5 VA However this system is only compatible with PV systems that use micro inverters B Sunny BEAM The Sunny BEAM system from SMA Solar Technology AG acquires the performance data of the PV system from the inverter s communication module COM This COM wirelessly communicates with other inverters and a hub shown below via 100 m range of password protected Bluetooth I http w3 usa siemens com us internet dms btlv residential residential docs Home SIE BR MicroinverterBrochure pdf 7 http www sma de en products monitoring systems sunny beam with bluetooth wireless technology html Technical Data 9226 12 Figure 2 2 Sunny Beam hub The hub shown in figure 2 2 is solar powered and displays the data graphically on a large screen and can log it in CSV format for excel compatibility when it is connected to a computer via its USB interface This is available in multiple languages and the system has a self diagnosis with potential solutions The accuracy and measuring the performance of the PV system is dependent on inverter which are the most common point of failure in PV system This also defines the level of accuracy making it impossible for the user to control and customize it C Maximum Peak Power Tracker The aforementioned monitoring system depends on inverter to gather data Inside the inverter are Maximum Power Point Trackers MP
66. urce to 5V This 4V drop at 0 52 A results in 2 08 W of heat This is a prime example of an application where a DC DC buck converter would be much more efficient Because the 7805 is very close to the SD card of the Rascal micro to avoid the heat from damaging the SD card the server was powered directly with 5V The initially the Rascal micro did not have a serialRead function With some advice from the creator this function was implemented In conjunction with that a new webpage was created to test the initialization of Oasis starting with connecting with to DMM This was accomplished using one of the existing test pages as a template where clicking a button would call the Server s OasisConnect function which mirrored the DMM s connect2server function for call and response This initial step was successfully implemented however due to limited time and knowledge of JavaScript and HTML this was the only task that was accomplished B Power block The components that make up the power block are the battery the battery charger and the PoE module In compliance with the battery chosen for the DMM a lithium ion battery was also used for the server The only difference lies in capacity where this battery is a temporary replacement for the DMM s main battery which theoretically would last 27 days This replacement battery s capacity was restricted so that the user could leave the battery for multiple days at a time That said batteri
67. ut was 5V which was far from the 2V quiescent point stated in the datasheet In addition I was unable to acquire ring concentrators before I ran out of time Should the concentrators had been acquired and design to expose the sensor to 7G A I expected 2 16758 mV at the output using my laptop cable Given this setup 71 42mV A would be observed which corresponds to 534 12 uA resolution Together with the achieved 10 mV resolution the DMM would have had a 5 3412 uW resolution C Power Block The main components of this block were the battery and the boost converter to increase the battery s output voltage to the microcontroller s input voltage Battery In the world of rechargeable batteries there are two main types acid and alkaline Only alkaline types were considered because acid freeze in cold climates rendering them unreliable 50 Within alkaline the batteries differ based on the chemistry and given said chemistry characteristics such as charging method depth of discharge DoD and disposal method vary Only Lithium based chemistries were considered because nickel metal hydride NiMH had a n output voltage below the desired range and Nickel Cadmium battery contain a heavy metal that is hazardous to the environment so they have a high disposal cost associated with them and are not environmentally friendly Technical specifications o Voltage 3 3V 5V o Continuous use 2190 h three months worth o Minimum Capacity
68. was connected to the serial clock pin of the SPI breakout In spite of this the SPI transfer worked and readings using the MX7705 were displayed From time to time the results would be zero regardless of the input To determine the source of this problem a few print statements were added to see if the registers were not set properly These print statement indicated that the registers were set properly so I power cycled the board and everything was functioning again but the voltages were still very inaccurate I then experimented with the reference voltage and the circuit was working once more with a reference of 0 68V After taking the circuit apart to take it home for Christmas and putting it back together again once I returned to the campus the data ready pin stayed HIGH which corresponded to the ADC being occupied During Christmas break I added comments and changed the SPI mode to 3 so that the serial clock polarity and phase would be on the rising edge and set as the reference 43 voltage to 2 5V instructed by the datasheet Knowing that the wiring might have changed I reevaluated the wiring and power cycled but this did not fix the issue and neither did resetting the ADC I stopped using the serial clock as the clock source of the ADC though this worked before and I broke down the code into parts and ran each part on after the other adding an extra layer after each success Many false diagnoses were made but as you can see in Appendix A f
69. ystems where individual receptacles and individual appliances are measured Of course the middle ground of these two levels is a hybrid system which monitors individual sets of panels and circuits inside a house 2 1 1 Production monitoring system Prior Art Given that team BEMANY s goal was to balance production and consumption monitoring each individual panel is very important therefore this section will evaluate some of the remote PV monitoring systems that have panel level monitoring to maximize the level of information A Enphase Enlighten Monitoring system As the name implies this type of monitoring system measures the AC voltage Siemens micro inverter system comes with a panel level monitoring system which relies on the voltmeter 11 inside the communication gateway to collect data from the load center I amp i As shown in figure 2 1 the data is then uploaded to a web based software via an Ethernet broadband router that plugs into any standard AC outlet The software enables remote monitoring through web enabled devices such as smartphones and tablets D Power Line Communications Internet Communications I PV Modules and I OLA ZA I a gt Envoy Broadband Communications Router ee Gateway Power Line el Enlighten web application Figure 2 1 Enphase Enlighten Monitoring system This system offers 24 7 monitoring amp analysis advanced data management amp storage and auto

ECE Aspects of Zero-Energy House - Worcester Polytechnic Institute

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