duke university photovoltaic solutions task # 2 advisor ... · the lightaware module the lightaware...
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Duke University
Photovoltaic Solutions
Task # 2
Advisor: Dr. David Schaad
Adam Dixon
Eric Fails
Lee Pearson
Steven Worrell
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WERC Environmental Design Competition
Task 2:
Photovoltaic System Performance Indicator
Duke University
Photovoltaic Solutions
WERC 2008
WERC Environmental Design Contest
New Mexico State University
Las Cruces, NM
April 6-9, 2008
Photovoltaic Solutions
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Table of Contents
Executive Summary ........................................................................................................................ 4
Task Identification .......................................................................................................................... 6
Problem Statement: ..................................................................................................................... 6
Global Photovoltaic Marketplace: .............................................................................................. 6
United States Photovoltaic Marketplace: .................................................................................... 7
Existing PV Monitoring Systems................................................................................................ 7
Motivation ................................................................................................................................... 8
Full Scale Design Description ........................................................................................................ 9
The LightAware Module............................................................................................................. 9
Data Processing ......................................................................................................................... 10
User Interface ............................................................................................................................ 11
Full Scale Diagram ................................................................................................................... 12
Bench-scale Diagram .................................................................................................................... 12
Bench-scale Lab Results ............................................................................................................... 13
Technical Evaluation of the Bench Scale ..................................................................................... 14
Signal Acquisition ..................................................................................................................... 14
Signal Processing ...................................................................................................................... 15
Display ...................................................................................................................................... 16
Waste Generation ...................................................................................................................... 16
Components of Performance Indicator System: ........................................................................... 16
Installation Instructions & Safety Warnings ................................................................................. 21
User instructions & Maintenance .................................................................................................. 22
References ..................................................................................................................................... 23
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Executive Summary
Current monitoring systems are difficult for most consumers to use, resulting in widespread
underperformance of photovoltaic systems. Photovoltaic Solutions addresses this problem by
displaying key diagnostics on both a wireless display unit and on the user’s computer. Because
consumers demand maximum system efficiency, and the monitoring system is the interface
between the consumer and the photovoltaic system, photovoltaic suppliers are under increased
pressure to provide state of the art monitoring systems.
Currently rated at nearly 2.3 billion dollars, the global photovoltaic market has experienced 25%
growth annually for the last decade due to strong technology adoption in European and Asian
marketplaces. The environmentally friendly aspect of solar energy cannot be understated when
assessing the future growth of the photovoltaic marketplace, and the total global market is
expected to grow 30-40% annually for decades.
The LightAware system combines simple technology to produce innovative monitoring statistics.
By measuring the intensity of incident sunlight using phototransistors, the LightAware System
can calculate the optimal expected power output. Using this metric the LightAware system
calculates the instantaneous efficiency of the solar panel system on the user’s home and tracks
this information over time. Competitor’s monitoring systems fail to monitor efficiency, instead
preferring only to monitor instantaneous power output. Monitoring power output is certainly
important, however, basic users cannot diagnose underperforming solar panels because they do
not know what they should be expecting. In our price range, no competitors offer the results and
ease of use that we can for our customers.
The information that the LightAware System collects is transmitted wirelessly to the user’s home
computer and is then rebroadcast over the internet. This allows for the user to check up on
his/her PV system at home, at work, or in the car listening to some tunes on their Ipod Touch.
LightAware also includes a digital display that can be mounted in a convenient location within
the home. In the event of a PV system malfunction, the user is notified via email and alert on
their home computer. With a click of a button, the user can send a help request to one of
Photovoltaic Solutions qualified service staff who can work through the issue via communication
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over the internet, or can arrange a service visit if the problem cannot be fixed remotely. As the
number of users of our system expands in a neighborhood, users can compare their efficiency
against their neighbors as another check to monitor performance. This capability also helps our
technicians and will decrease service time.
At Photovoltaic Solutions we are convinced that our LightAware monitoring system is a viable
alternative to existing monitoring systems. For such a small price, we offer the most capability,
flexibility, and ease of use for users of any ability. We have effectively solved the problem of
communicating solar panel performance to the user in a cost effective way.
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Task Identification
Problem Statement:
Develop and demonstrate a system to determine that a residential utility-interactive PV system is
operating properly and that the ac power output is following the solar power available to the PV
array.
Global Photovoltaic Marketplace:
Currently rated at nearly 2.3 billion dollars, the global photovoltaic market has experienced 25%
growth annually for the last decade due to strong technology adoption in European and Asian
marketplaces. Japan and Germany account for over half of all photovoltaic power production
globally, and still experience some of the fastest industry growth patterns. Accordingly, the
marketplace is dominated by foreign producers, mostly located in Western Europe and Japan.1 In
2006, photovoltaic systems produced by Sharp, a Japanese company, generated 18% of all
residential photovoltaic power world wide.2
International success has been driven by an expanding marketplace and generous government
subsidy programs. Aggressive tax incentives along with mandated energy ‘buy-back’ programs
for large energy producers have made solar technology available to on-grid consumers regardless
of income level.1 While solar energy production is not cheaper than traditional fossil fuels, the
technology appeals to many consumers in Western Europe, which is well ahead of the United
States and much of the world in environmental consciousness.
Off-grid photovoltaic production is an emerging marketplace that accounted for roughly 7% of
total sales last year. Off-grid systems, as the name implies, are not tied into the power grid, and
do not participate in energy ‘buy-back’ programs. However, consumers in regions of both
developed and developing nations who lack dependable energy sources have found solar to be a
reliable electricity source.3
The environmentally friendly aspect of solar energy cannot be understated when assessing the
future growth of the photovoltaic marketplace, and the total global market is expected to grow
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30-40% annually for decades. As producers continue to market solar energy as a mainstream
technology and are able to secure government reimbursements, photovoltaic system production
will continue to quickly expand internationally.
United States Photovoltaic Marketplace:
Perhaps the most unique aspect of the photovoltaic industry is that, until very recently, nearly all
of its growth has occurred without the participation of the United States. Widespread adoption of
photovoltaic technologies is inevitable, and as the environmental consciousness of consumers in
the United States increases, the market will quickly expand. In fact, many reports suggest that the
United States’ potential for photovoltaic energy production is more than twice that of already
well established markets, suggesting that when the United States does enter the marketplace, the
total international market could be buoyed up to well beyond 25 billion dollars.2
However, until the United States adopts energy subsidy programs similar to those in Germany
and Japan, photovoltaic energy production will be limited to wealthy and environmentally
conscious consumers who are willing to purchase the systems on their own. The total United
States photovoltaic market is rated close to 300 million dollars, with the residential component
comprising nearly half of the total marketplace. First Solar, the leading United States based
manufacturer, accounted for roughly 25% of total United States sales in 2006, and is actively
lobbying state legislatures to subsidize photovoltaic energy production.3
Even without active government support behind the solar movement, the United States
photovoltaic market has experienced 20% growth annually since 2000, due largely in part to
decreased photovoltaic production costs and an increased interest in green technologies.2
Existing PV Monitoring Systems
Systems are already available that offer similar monitoring capabilities. High end monitoring
systems (used more institutionally) monitor the PV Array and the environmental factors that
affect it. These systems are also equipped with real time displays that are easy to understand and
are typically hooked up to a kiosk or computer internet LAN setup. They range from simple to
complex so anyone can use them and they cost between $2,000 and $15,000. Intermediate
monitoring systems (used both institutionally and residentially) monitor energy, occasionally
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power, and some environmental factors that affect the system. These systems are typically
connected directly to the internet and their ease of use varies greatly. They cost between $500
and $3,000. Low end monitoring systems (used more residentially) monitor energy and
sometimes also power. These systems may use kilowatt hour meters, direct inverter read-outs
and, remote LCD displays. They cost between $0 and $600.4 The price of our system will be in
the low end price range, however, the capabilities our system offers will exceed the existing mid
range products. As such we believe that our system gives a competitive advantage to our
company and a useful service for our customers.
Motivation
Current monitoring systems are difficult for most consumers to use, resulting in widespread
underperformance of photovoltaic systems. Photovoltaic Solutions addresses this problem by
displaying key diagnostics on both a wireless display unit and on the user’s computer. Because
consumers demand maximum system efficiency, and the monitoring system is the interface
between the consumer and the photovoltaic system, photovoltaic suppliers are under increased
pressure to provide state of the art monitoring systems. As the United States market expands to
serve individuals with less technical know-how, more efficient and consumer friendly
monitoring services must be developed to better serve this marketplace. Accordingly, this
consumer base can be expected to pay more for a more user-friendly monitoring system capable
of conveying complicated technical metrics of photovoltaic function through clear and easily
interpreted graphs and language.
A problem with current photovoltaic systems is undiagnosed underperformance, and consumers
who are not technically inclined have little hope of noticing underperformance of their
photovoltaic system, especially if they are still tied into on-grid power sources that can make up
for lack of solar production. Hence, monitoring systems that clearly indicate optimal
performance levels are in high demand, but technologies capable of delivering these metrics are
very rudimentary.
As a whole, however, both the domestic and international marketplace for photovoltaic systems
is poised for rapid growth in the coming decades, especially with the emergence of major
consumer bases in the United States and elsewhere. As populations become increasingly aware
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of the detrimental affects of traditional nonrenewable fuel sources on the environment, a strong
push on national and local governments to help subsidize solar power will further help to drive
the marketplace.
Full Scale Design Description
System indicators currently on the market provide information relating the current amount of
power being generated by the PV system to the theoretical maximum power. This measure of
efficiency is only useful when the panel is directly aligned with bright sunlight, and is of almost
no use during cloudy or overcast days or in the morning or evening. Our design instead measures
incident sunlight striking the panel, and uses empirical data to determine if the amount of power
being generated is consistent with the amount of power that should be generated for that much
sunlight. The LightAware Module is used as described below to determine how efficiently the
PV system is converting available sunlight into power. This measure of efficiency then
determines if the PV array is functioning properly, and communicates to the user through the
various interface possibilities described.
The LightAware Module
The LightAware monitoring system is housed in a durable plastic shell with openings to expose
the phototransistors to light. The plastic housing is white so that solar radiation is reflected to
keep the temperature of the module as low as possible. The NPN phototransistors produce an
output voltage proportional to the intensity of the incident sunlight. This output voltage is then
sent to the Microchip PIC 18F4250 microcontroller and undergoes a 10-bit analog to digital
conversion. The PIC 18F4250 is contained in a separate protective housing that is placed on the
underside of the solar panels to protect it from light and precipitation. Both the LightAware
Module and the PIC 18F4520 are mounted on the solar panel. The LightAware system
communicates with the data processing software using a wireless radio frequency protocol used
with PIC cards (rfPIC technology).
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Figure 1: The Light Aware Module which has three phototransistors: two imbedded at 45 degrees from the
vertical phototransistor.
Data Processing
The digital signals from the PIC 18F4520 are transmitted to the computer wirelessly for
processing using the rfPIC wireless transmission protocol. The rfPIC system is composed of an
RF transmitter on the solar panel and a receiver by the processing unit. The digital signals from
the rfPIC are fed into a Texas Instruments Digital Light Processing (DLP) device to convert the
signals into universal serial bus (USB) format. The DLP is a plug-and-play device, and is readily
recognizable by the signal processing software. The processing software will be written in C++
to perform the calculations on the data received from the DLP device.
The output from the inverter relays the amount of power generated by the panels at any given
time. This output is run through a voltage and current transformer and is fed into another PIC
18F4520 near the inverter. The PIC 18F4520 will perform a 10-bit analog to digital conversion
on this signal and will relay it to the DLP device.
The processing software will calculate metrics such as current power output, optimal power
output, instantaneous efficiency, and total power generated over the course of a day, month,
season, and year. These metrics will be saved on the computer and will be consulted to make
sure that the system is maintaining its optimum efficiency. If efficiency is progressively
decreasing, the system will alert the user through e-mail that the system is not performing at its
maximum efficiency. The user should seek the help of a professional electrician in this
circumstance.
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User Interface
Once the inputs from the LightAware sensor and PV system are processed in the owner’s
computer, there are many potential options for the use of this data. For the least involvement
from the user, the system will essentially operate in the background, and only notify the user
when there is a problem with the PV’s functionality. This notification can be done via email,
SMS text message, or notifications on the home computer. This would serve to alert the user to
potential problems, and would also contain information that can be accessed by a technician to
diagnose and solve the problem. A more in depth approach would involve daily monitoring of
solar power conversion efficiency, with monitoring available through the same means outlined
above. Similar to currently available monitoring systems, our design also includes a wireless
display that can be placed anywhere in the dwelling. Unlike current displays that give
efficiencies based on the total possible output of the system, our novel LightAware sensor allows
for calculation of an efficiency based on the amount of sunlight on the system. Because of the
large temporal variation in incident sunlight (both daily and monthly) this measure of efficiency
will be a great deal more revealing of how well the PV system is operating.
For added capabilities, the results of the signal processing can be transmitted wirelessly on the
user’s home wireless network (typically 802.11g). This will enable the user to check the status of
the solar panels from any computer with an internet connection. We will also supply a wireless
display device that can be mounted in a convenient location in the user’s home. This device will
communicate with the home’s wireless network to display metrics of the solar panel’s
performance.
The system will send self diagnostic information to the user through email. If, for some reason,
the monitoring system malfunctions and the signals cannot be adequately processed, the system
will alert the user to seek help from a professional electrician.
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Full Scale Diagram
Bench-scale Diagram
Figure 2: Schematic diagram of bench scale experiment. Photovoltaic array (1) with our ‘LightAware’
sunlight detection unit (2). The LightAware unit detects incident sunlight and transmits data to a
microprocessing unit (3), which then sends data for analysis and storage to a computer (6). Our system also
detects how much electricity is output from the inverter (5) through the use of a data acquisition card (4).
The 120 VAC line power (7) is transformed to 5 VDC to power the LightAware unit and the MPU.
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Bench-scale Lab Results
Table 1: Recordings for solar panel performance and LightAware module performance
Data from 3/17/08
Solar Panel Transistor Readings
Time Voltage Current Power Morn Noon After
1:30 PM 20.4 0.16 3.264 0.053 0.103 0.044
4:00 PM 20.3 0.44 8.932 0.039 0.12 0.86
4:15 PM 19.5 0.45 8.775 0.012 0.102 0.972
4:30 PM 19.4 0.13 2.522 0.015 0.08 0.324
4:45 PM 19.46 0.14 2.7244 0.011 0.082 0.292
5:00 PM 20.8 0.27 5.616 0.003 0.12 0.43
Data was collected on March 17th, 2008 in Durham, NC at Duke University’s Smart Home
residence on Faber Street. A BP 10-watt solar panel was used as the solar panel of interest and
voltage and current readings were taken using digital multimeter. A bread-boarded LightAware
unit was placed next to the solar panel and readings were taken concurrently with the solar panel
readings using a digital multimeter. This data was collected over the course of the day and
plotted using Microsoft Excel with linear regression tools. This allowed for the power of the
solar panel to be related to the transistor voltage readings from the bread-boarded LightAware
module.
As shown in Figure 3 a linear relationship exists between solar panel power and transistor
voltage from the LightAware unit. However, it is very likely that the constant of relation that is
found will vary from solar panel to solar panel since sizes and efficiencies will be slightly
different. As such, each module sold will have to be calibrated on site to ensure that it will give
reliably information to the user throughout its use.
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Figure 3: Relation of solar panel power output to transistor voltage from the LightAware Module
Technical Evaluation of the Bench Scale
The photovoltaic monitoring system contains three primary technical components, all of which
will be discussed in their own sections:
• Signal Acquisition
• Signal Processing
• Display
Signal Acquisition
The LightAware monitoring system gauges the intensity of the incident sunlight using NPN
phototransistors produced by PerkinElmer Optoelectronics. The NPN phototransistors were
chosen because they have highly modifiable internal gains and direct current output responses
that vary differentially based on incident sunlight. The VTT1015H model was specifically
chosen because it exhibits a similar spectral response as most solar panels. The NPN
phototransistors must be powered with a +5 VDC bias voltage at the collector, and the output
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voltage is read from the emitter. Photodiodes were also considered because they are passive
elements, but they have no capability for internal gain, which could affect the fidelity of the
acquired signal.
The monitoring system also monitors the output from the inverter. The inverter’s output is
typically 120 or 240 VAC at various amperages. Our system transforms the output from the
inverter to roughly 6.3 volts (at 0.6 mA) using a Stancor transformer for acquisition by a
National Instruments DAQ card. (Note that the Full Scale design uses another PIC card instead
of the DAQ card).
Signal Processing
The Microchip PIC 18F4520 takes the outputs from the NPN phototransistors and performs a 10-
bit analog to digital conversion. The PIC 18F4520 is programmed in C language using
hardcoded analog to digital functions. The PIC 18F4520 is powered by the same +5 VDC power
source as the NPN phototransistors. The maximum voltage from the NPN phototransistors on a
bright day has been calibrated to be +1V, so the PIC is able to convert the analog signal with a
resolution of approximately 1mV. Analog to digital conversion is necessary because the values
must be transmitted over very long distances, and weak analog signals are subject to attenuation
and distortion. The digital signals from the PIC 18F4520 are fed into a Texas Instruments Digital
Light Processing (DLP) device to convert the signals into universal serial bus (USB) format. The
DLP is a plug-and-play device, and its outputs are readily recognizable by the LabVIEW
software.
The digital signals from the PIC and the DAQ are fed into a computer for analysis using
LabVIEW software. This software takes the data from the NPN phototransistors and calculates
how much power the photovoltaic system should be producing based on the incident sunlight.
This calculation is performed using calibration constants determined during the testing of the
bench scale. The optimal power output is then compared to inverter output to calculate system
efficiency.
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Display
The display for the bench scale is part of the LabVIEW software interface. This display was
chosen because it is a cost effective way to simulate a real display device. However, in the full
scale product, the computer performing the data analysis will broadcast the results over the
internet using FTP protocol.
Waste Generation
The largest component of the waste stream in a combined PV system and indicator is that of the
main system itself. Current research suggests that in the near future recycling of PV systems will
be standard practice, which ensures that the potentially hazardous materials involved will not
only be removed from landfills but will be reused as raw materials.5 The additional electronics
and wiring implemented in our proposed design would insignificantly change the overall waste
generated at the end of the system lifetime. In terms of individual components, the
phototransistors are made of aluminum and silicon, and are no more toxic than any other
electrical component. It may not be as economically feasible to recycle the materials in these
components as it is for entire PV systems, but because the entire system will be sent to a
recycling facility it can be assumed that the monitoring system will at least be disposed
properly.
Components of Performance Indicator System:
Component Description Cost Picture
Microchip
PIC 18F4520
A PIC is a Programmable Intelligent
Computer which is a microcontroller capable of performing simple analog to digital conversions using C language code.
$2.36
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=13
35&dDocName=en010297 http://www.voti.nl/common/18f452.jpg
Schematic
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SOURCE: http://ww1.microchip.com/downloads/en/DeviceDoc/39631D.pdf
Component Description Cost Picture
National Instruments DAQ USB-6008
The National Instruments USB-6008 multifunction data acquisition (DAQ) modules provide reliable data acquisition at a low price. With plug-and-play USB connectivity, these modules are simple enough for quick measurements but versatile enough for more complex measurement applications.
$159
http://sine.ni.com/nips/cds/view/p/lang/en/nid/14604
Schematic
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SOURCE: http://www.ni.com/pdf/manuals/371303k.pdf
Component Description Cost Picture
Stancor Power
Transformer P-6465
A transformer transforms voltage from high to low. Transformer; Chassis; Pri:117V; Sec:6.3VCT; Sec:0.6A; Lead; 50/60Hz; 2.38In.In.W; 1.38In
$9.44
http://www.alliedelec.com/Search/ProductDetail.asp?SKU=928-3027&SEARCH=&MPN=P-6465&DESC=P-6465&R=928-3027&sid=47CC9100396C617F
Schematic
SOURCE: http://www.alliedelec.com/catalog/pf.aspx?FN=974.pdf
Component Description Cost Picture
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Perkin Elmer phototransistor VTT1015H
An NPN phototransistor produces an output current when exposed to photons. The collector receives a 5VDC bias voltage and the output voltage is read from the emitter.
($2.76) x (20) = $55.14
http://www.alliedelec.com/Search/ProductDetail.asp?SKU=980-
0102&SEARCH=&MPN=VTT1015H&DESC=VTT1015H&R=980%2D0102&sid=4796838071E3617F&tab=specs#tab
Schematic
SOURCE: http://www.alliedelec.com/catalog/pf.aspx?FN=1864.pdf
Component Description Cost Picture
Microengineering LabsLAB-X2 Experimenter Board
The development board powers the PIC. The LAB-X2 contains the circuitry required by the PICmicro® MCU to operate: 5-volt power supply, oscillator, reset circuit, as well as an RS-232 serial port and basic analog and digital I/O. Both 40 and 28-pin DIP microcontrollers are accommodated. All of the pins on the MCU are wired to a 40 pin connector which can be used to connect your prototype circuitry.
$79.95
http://www.microengineeringlabs.com/products/labx2.htm http://www.microengineeringlabs.com/ima
ges/Detail_JPGs/LABX2A_detail.jpg
Schematic
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SOURCE: http://www.microengineeringlabs.com/downloads/labx2sch_06.pdf
Component Description Cost Picture
Mouser DLP USB Device DLP-USB245M-G
The DLP USB Device converts the digital signal from the PIC to a USB signal which is then sent to the computer for signal processing.
$28.75
http://www.mouser.com/search/ProductDetail.aspx?qs=CoW5K%2FMp%2F73t5w3WDhf9Ow%3D%3D
Schematic
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SOURCE: http://www.ftdichip.com/Documents/DataSheets/DLP/dlp-usb245m13.pdf
Installation Instructions & Safety Warnings
Installation of the monitoring unit would ideally be performed at the time of installation of the
overall PV system, and done by qualified electricians. The most important aspect of installation
is the alignment of LightAware system along an east-west axis, such that it closely mimics the
sun’s pattern. The system wiring should done according to the provided circuit diagrams. The
PIC card should be located in such a way as to reduce the possibility for weather damage,
similarly it should be located out of direct sunlight so as to reduce the possibility of thermal
damage to the unit.
The following safety precautions will be taken:
• When unplugging the power supply cord, be sure to grasp the power supply plug; never
pull on the cord itself.
• Never plug in nor remove the power supply plug with wet hands, as doing so may cause
electric shock.
• To prevent a fire or electric shock, never open nor remove the unit case as there are
sensitive components inside the unit that can be damaged or cause harm to operator.
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• Do not insert nor drop metallic objects or flammable materials in the ventilation slots of
the unit's cover, as this may result in fire or electric shock.
• Use the unit only with the voltage specified on the unit. Using a voltage higher than that
which is specified may result in fire or electric shock.
• Do not cut, kink, otherwise damage nor modify the power supply cord. In addition, avoid
using the power cord in close proximity to heaters, and never place heavy objects --
including the unit itself – on the power cord, as doing so may result in fire or electric
shock.
• Install the unit only in a location that can structurally support the weight of the unit and
the mounting bracket. Doing otherwise may result in the unit falling down and causing
personal injury and/or property damage.
• Do not use other methods than specified to mount the bracket. Extreme force is applied to
the unit and the unit could fall off, possibly resulting in personal injuries.
User instructions & Maintenance
Our system software is designed for flexibility in terms of the amount of technical data offered
by the display. For the most basic level, the user would only know of the monitoring system if
the PV is not working properly, and would be notified via email. For the more technology savvy,
information on the daily efficiency of the system would be available. In either case, when the
system is not operating at peak efficiency, a visual inspection of the system would be the first
step. If this does not reveal the problem (for example, if an object is blocking the solar array)
then a qualified PV system electrician should be contacted to perform a system analysis.
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References
1 “Trends in Photovoltaic Applications: Survey report of selected IEA countries between 1992 and 2005.” International Energy Agency.
Accessed September 14, 2007. www.suterdruck.ch
2 “The Global PV Industry: Technologies, Applications, and Drivers for Future Growth.” Interstate Renewable Energy Council (IREC).
Presentation given July 19, 2007.
3 First Solar, Inc. 2006 Annual Report to Investors. 4 Heliotronics, Residential Monitoring, http://www.heliotronics.com/papers/CH_ResMonitoring.pdf
5 J.R.Bohland,et al. : :Possibility of Recycling of Silicon PV Modules, 26" IEEE PVSC( 1997)
Duke University Edmund T. Pratt, Jr. School of Engineering
DEPARTMENT OF CIVIL AND ENVIRONMENTAL TELEPHONE (919) 660-5200
ENGINEERING FAX: (919) 660-5219
BOX 90287 HTTP://WWW.CEE.DUKE.EDU
DURHAM, NORTH CAROLINA 27708
March 17, 2008
Memorandum To: Professor David Schaad From: Professor Jeff Peirce Re: Financial Audit of WERC Contest: Task 2 “Photovoltaic Solutions” The strengths and weaknesses of the financial plan for “Photovoltaic Solutions” are listed below. Strengths: Throughout the text the authors show an appreciation for and an understanding that:
• recent decreases in production costs of photovoltaic systems have led to technical
solutions that otherwise would not be available (page 6); • consumers currently demand systems that operate at maximum efficiency (page
6); • both the US and international markets (supplies and demands) for photovoltaic
systems could be entering a period of rapid expansion (pages 4 and 6); • full-scale design incorporates many aspects of bench scale studies but also can
include important changes to take advantage of economies of scale and thus provide the systems at lower costs (page 7);
• the LabVIEW software interface display was selected in a cost effective manner (page 10);
• the marketplace may not find it economically feasible to recycle the materials in the individual components of the photovoltaic systems (page 11); and,
• the costs of the system components are well documented and available in the literature (page 11, 12, 13, 14 and 15).
Weaknesses and Suggestions: 1. All considerations of the very important economic analysis and financial plan,
including those topics mentioned above but sprinkled throughout the document, should be included in a separate section of this report. This Economic Analysis and Financial Plan section must be thoroughly developed and thoroughly referenced, and the title of this section must be included in the Table of Contents; and,
2. Engineering economic analysis including estimates of present worth and/or equivalent annual worth could be used as part of this discussion to benchmark the relative value of the total cost of the proposed solution.
Duke University Edmund T. Pratt, Jr. School of Engineering
DEPARTMENT OF CIVIL AND ENVIRONMENTAL TELEPHONE (919) 660-5200
ENGINEERING FAX: (919) 660-5219
BOX 90287 HTTP://WWW.CEE.DUKE.EDU
DURHAM, NORTH CAROLINA 27708
March 17, 2008
Memorandum To: Professor David Schaad From: Professor Claudia Gunsch Re: Legal Audit of WERC Contest: Task 2 “Photovoltaic Solutions” Beyond the design and manufacture liability of the PV system and indicator, this product’s production and disposal will need to be performed in accordance with the Resource, Recycling, Conservation, and Recovery Act (RCRA). As duly pointed out by the research team, at the present time, “the largest component of the waste stream in a combined PV system and indicator is that of the main system itself”. Because many solvents, metals and other hazardous components are incorporated into electronic manufacturing, it is important to think about the disposal of such items. RCRA was enacted to protect the public from harm caused by waste disposal, to encourage reuse, reduction and recycling and to clean up spilled or improperly stored wastes. All of these aspects are pertinent to this project and need to be addressed. The individual components indicated in the proposal are rather cheap, however their disposal costs should be taken into consideration. The team indicates that in the future many of the components will be recycled and if this were the case, the requirements under RCRA are likely to be lessened. The design and manufacture of the system for implementation could expose the design professional and the manufacture to legal liability. Because the proposed use for the indicator is to provide users with information as to the efficiency of an installed PV system, the liability should be low. It does not appear that there would be substantial expenses associated with such system failing and limited adverse health effects can be expected from its operation. Thus, the legal liability should be low. Nonetheless, it would be worthwhile to incorporate an automatic shutoff mechanism if the system and/or indicator were to become wet or improperly operate beyond specific limits. In addition, it would be prudent for the manufacturer to insure themselves.
Duke University Edmund T. Pratt, Jr. School of Engineering
DEPARTMENT OF CIVIL AND ENVIRONMENTAL TELEPHONE (919) 660-5200
ENGINEERING FAX: (919) 660-5219
BOX 90287 HTTP://WWW.CEE.DUKE.EDU
DURHAM, NORTH CAROLINA 27708
March 17, 2008
Memorandum To: Professor David Schaad From: Professor Helen Hsu-Kim Re: Safety Audit of WERC Contest: Task 2 “Photovoltaic Solutions” The team covered most of the important environmental health and safety items related to the implementation of their system design.