Get our free book (in Spanish or English) on rainwater now - To Catch the Rain.

# Changes

## Solar Photovoltaic Cells for the Kingston Home FAQ

, 18:34, 8 September 2011
m

{{QASpage}}
|}
A [[solar cell]]{{wpw|solar cell}}, or photovoltaic (PV) cell [[Photovoltaics]], is a device that converts solar energy into electrical energy via the [[photoelectric effect]]{{wpw|photoelectric effect}}. A [[solar array]]{{wpw|solar array}} is a grouping of individual solar cells that are electrically connected to produce electrical power. By installing a solar array, users can generate electricity for their personal use or for distribution on a connected electrical grid. Solar arrays can offer environmental and financial benefits for both the homeowner and the community at large. Many people are curious about solar technology and this page aims to answer questions relating directly to photovoltaics in general and also addresses specific questions related to installing a PV array in Kingston, Ontario, Canada.
== Technological FAQs ==
===How do solar cells work?===
Solar cells function by converting electromagnetic radiation (primarily light from the sun) into electrical energy. Solar cells convert light into electricity using the [[photoelectric effect]]{{wpw|photoelectric effect}}. When light strikes the active material in a photovoltaic cell, the light (in the form of [[photons]]{{wpw|photons}}) promotes [[electrons]]{{wpw|electrons}} in the material to a higher state of excitement. To maintain charge neutrality, an excited electron will also have a corresponding ‘hole’ that balances the electron’s charge. The excited electron will eventually come back down and re-united with an electron hole, so a solar cell needs to collect the electrons and holes before this occurs. A [[P-N junction]]{{wpw|P-N junction}} can be used to collect the electrons and holes, generating an electrical potential that allows a current to flow. Solar cells are often discussed in terms of efficiency, which is a measure of how much electrical power is output per unit of incident light input power. For example, if a solar array has an overall efficiency of 10% and an exposed area of 1 square meter, the expected electrical power output would be 10 watts if the incident light [[irradiance]]{{wpw|irradiance}} was 1000 watts per square meter.
A substantial amount of information on the technical workings of photovoltaic exists on the Internet. Several good starting resources can be found here:
Some of the significant advantages of generating power from photovoltaic cells include:
* Low operating and maintenance costs once the panels are installed.
* Environmentally friendly source of [[renewable energy]]. Reduces reliance on more carbon-intensive or GHG-intensive energy generators such as coal or fossil fuels.
* Independence from utility companies can either reduce/eliminate utility costs or serve as another income stream to the household.
Some of the disadvantages to meeting your power needs with solar PV technologies:
* Producing power from solar PV is sensitive to weather conditions (i.e. snow or cloud cover), and no power is generated at night.
* [http://www.portablesolarpanels-forsale.com/solar-energy-facts Solar Energy Facts]<ref>http://www.portablesolarpanels-forsale.com/solar-energy-facts ''Solar enegy facts. 2010.''</ref>
* [http://www.portablesolarpanels-forsale.com/solar-energy-facts Solar Energy Facts]<ref>http://www.portablesolarpanels-forsale.com/solar-energy-facts ''Solar enegy facts. 2010.''</ref>
=== What are the different types of solar cells?===
*'''First generation solar cells''': The photovoltaic industry began around crystalline silicon and the first solar cells made using pure crystalline silicon are commonly referred to as first generation. These cells use a single junction and have high efficiencies, but use a large amount of pure crystalline silicon, making the technology relatively expensive. Most of the current market share belongs to first generation devices.
*'''Second generation solar cells''': In an effort to reduce the cost of solar cells, a second generation of photovoltaic devices was investigated and is characterized by devices using very small amounts of source material. By reducing the material required per cell, the overall cost is reduced compared to first generation devices. However, second generation technologies do not have the high efficiencies obtained by the pure crystalline silicon devices found in the first generation of solar technologies. Second generation photovoltaics are commonly called 'thin-film' solar cells, due to the small amount of material required as compared to first generation technology. Common thin-film technologies include amorphous silicon, cadium telluride, and copper indium gallium selenide. As well, new advances into [[Dye-sensitized solar cell|dye-sensitized ]] and organic/polymer photovoltaics are emerging technologies. Second generation solar technologies are currently beginning to expand into the consumer market.
*'''Third generation solar cells''': The third generation of photovoltaics aims to achieve the high efficiencies of the first generation and the low cost of the second generation devices. Third generation technologies are under siginificant research in efforts to push the obtained efficiencies to new records using novel techniques such as multi-junction cells. Multi-junction cells can be visuallized as several cells stacked on top of each other, with each cell optimized for a different part of the optical spectrum. This allows for more effective collection of all wavelengths of light and a higher overall efficiency. Third generation solar cells are currently found mainly in research labs and universities.
|}
</div>

=== Does the efficiency of a solar cell decrease over time?===
Yes, solar panels are environmentally friendly. The main concern regarding the environmental benefit of solar panels is the amount of energy required to manufacture them, in order to address this concern the energy payback time of solar panels has been determined. The energy payback time (EPT) of a technology is commonly defined by the following equation:
:$\, EPT = \frac{EnergyIn (MWMWh)}{EnergyOutput AnnualEnergyOutput (MWh/year)}$ [someone please fix units; see discussion]
This equation takes into account the energy required for manufacturing and installation (EnergyIn) and compares it to the annual energy output (EnergyOutput). The EPT of a panel is dependent on many factors such as manufacturing process, the panel efficiency, the amount of carbon in the electricity mix where the panel is manufactured, the geographical location of where the panel is operating along with many other factors. That being said many Life Cycle Analyses have been conducted on solar photovoltaic panels and a range of payback times have been determined, Alsema and Fthenakis found a range of EPT of 1-2.7 <ref>Alsema, Fthenakis"Photovoltaics Energy Payback Times, Greenhouse Gas Emissions and External Costs: 2004 - early 2005 Status", Progress in Photovoltaics: Research and Applications 14, no.3 (2006):275-280</ref> years while the National Renewable Energy Laboratory [http://www.nrel.gov NREL] found EPTs ranging from 1-4 years. An EPT has not yet been determined for Kingston, Ontario however with average panel life times of 20 – 30 years even with higher EPT the solar panels continue to be environmentally friendly.
=== Can they be recycled? ===
While there are many types of solar cells available, most of the current photovoltaic technologies are fully recycleable. The majority of commerical solar cells are primarily made of silicon, which can be fully recovered. A number of different chemical processes can be used to recycle the silicon in the photovoltiac cells into pure silicon wafers. As well, the glass, aluminum frame and electrical wiring can be recovered and recycled.<ref> Muller, A., Wambach, K., Alsema, E. ‘’Life Cycle Analysis of a Solar Module Recycling Process’’, (2003) Materials Research Society. Avaliable online at http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=6228&DID=170203&action=detail </ref> Recycling of solar panels is economically attractive as most of the raw silicon processing steps can be bypassed when using recycled materials.<ref> Fthenakis, V.M.’’End-of-life management and recycling of PV modules’’, (2000) Energy Policy, Vol. 28, Issue 14. Pg. 1051-1058. Available online at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2W-4177N2J-7&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=3ac8336c226cb9e89cac8f0b6381708b </ref> The recycling process is currently done by several companies such as [http://www.solarworld.de/solarmaterial/english/modulrecycling/ SolarMaterial.]
For other photovoltaic technologies, such as Group-III thin film technologies, the material components can still be recovered but the recycling technolgies are not as well established as silicon-based photovoltaic recycling. For example, [[cadmium telluride photovoltaics]]{{wpw|cadmium telluride photovoltaics}} can be recovered using a [[pyrolysis]]{{wpw|pyrolysis}} process.<ref> Patent for Process for recycling CdTe/Cds thin film solar cell modules. Available online at http://www.freepatentsonline.com/6572782.html </ref> It is also important to note that the long lifespan of photovoltaic panels (upwards of 20-30 years) will allow for the further development of recycling technologies.
Some manufacturer's indicate recycling in their goals:[http://www.firstsolar.com/recycling.php]
These include:
# [http://www.downundersolar.ca Downunder Solar and Electrical]
# [http://www.strathconasolar.com Strathcona Solar]
# [http://www.ecoaltenergy.com Eco Alternative Energy]
# [http://www.quantumenergy.ca/ Quantum Renewable Energy Inc.]
=== What do the terms on-grid, grid-connected, grid-tied and off-grid mean? ===
On-grid, grid-connected or grid-tied means connected to the utility electrical grid; power produced by the panels is fed directly to the main power grid in the city. Off-grid refers to systems that are not connected to the utility electrical grid; all power generated by the panels is either stored or used by the building they are fixed to. An off-grid system must be custom designed by a [[solar power ]] expert. <ref>http://www.gepower.com/prod_serv/products/solar/en/faqs/resid_sys.htm#faq9</ref>
Solar cells will produce more electricity if the incident light is concentrated by using mirrors or reflectors. Concentrating the light through optics and reflectors can be an economical way to improve the power capacity of a system. An example of a light concentrator device is a fresnel lens system, and an example of using this technology with solar cells can be found [http://news.cnet.com/8301-11128_3-10007431-54.html here.]
[[Solar trackers]]{{wpw|Solar trackers}} are devices operate by changing the angle of the solar panels to follow the sun as it moves across the sky. With the solar panels facing the sun for most of the day, the power generated is larger than the power generated without the tracker installed. Trackers come in a variety of options depending on the different number of rotational axis used to track the sun. The cost of the tracker often is not worth the additional power increase they provide.
It is important to be aware of the concentrator and tracking options for solar installations, but the cost often does not justify their installation. It is a good idea to ask about them when consulting with a company for a roof-top solar installation. A good resource on solar trackers/concentrators can be found [http://www.pvresources.com/en/concentrator.php here.]
Throughout the ongoing development of the draft Program Rules over the next few months, options for ensuring the fair treatment of early movers under RESOP will be explored and discussed with stakeholders.
== Other Resources ==
[http://www.gosolarontario.ca/en/faq_gs.asp#f Go Solar FAQs]
==NEWS on Ontario FIT==The '''Kingston Whig Standard''' featured an article last week on the high volume of applications for the microFIT program and the subsequent backlog, http://www.thewhig.com/ArticleDisplay.aspx?e=2597534. SWITCH recently learned that the OPA are re-deploying lots of people to work on the backlog of rooftop solar microFIT applications. A significant number of applications should be completed by mid-June and they should be back on schedule by August.<br/> Kingston: '''The Community Energy Partnerships Program (CEPP)''' covers up to 90% of eligible development costs to a maximum of \$200,000 for community power projects greater than 10 kW and no larger than 10 MW. Come to the SWITCH open meeting on July 9th and join Laurie Arron, Program Director for the CEPP and discover what kinds of projects can apply to CEPP, who is eligible, what kinds of grants are available and what costs they cover. For more information on the program, visit http://www.communityenergyprogram.ca/Home.aspx.  Kingston: The '''1000 Solar Rooftops Challenge''' will begin soon. Students will be going door to door, identifying homes with solar potential and delivering customized information to homeowners. The students will be available at various public events over the summer. SWITCH will be setting up a database of installed solar energy systems, recognizing the installers involved with the project.(June 1 2010) == Other Resources ==* [http://www.gosolarontario.ca/en/faq_gs.asp#f Go Solar FAQs]* [http://www.alternative-energy-geek.com/ Alternative Energy Geek]* [http://www.cansia.ca/ CANADIAN SOLAR INDUSTRIES ASSOCIATION]* List of PV manufacturers planned to meet 2011 Ontario content standards [http://www.cleanbreak.ca/2010/08/11/1000-mw-of-solar-module-capacity-announced-in-ontario-so-far-and-here-are-the-players/]* [http://gomakesolarpanels.com/ How to Make Solar Panels]
== Citations ==
11,551
edits