Solar Photovoltaic Energy Replication - Joshua Pearce
Wouldn't it be cool if there was a magical device that sat on your roof and quietly provided your home with all the free renewable electricity you and your family needed for your entire life. Ideally the device would actually be your roof (to cut down on the cost of roofing). It would be even better if the device could be made out of something common and inexpensive (like beach sand) and draw on an energy source available everywhere people live – so everyone could enjoy it. Finally, it would need to be such a prolific electricity producer that it could produce enough electricity to make itself - to self replicate so your grandchildren and their grandchildren and so on, could enjoy it too.
Amazingly, such a device already exists and is becoming a reality for an exponentially growing number of people. The devices are solar photovoltaics (PV), which turns sunlight directly into electricity. Solar PV have been around for a while – you probably have an old calculator that was powered with them. The only reason that you may not have a solar powered house now is because in our somewhat arbitrary and highly subsidized economy, fossil fuels have been allowed to externalize the majority of their costs and thus solar electricity appeared more expensive. Fortunately, this is no longer the case for an ever increasing percent of the world's population. Solar PV has been expanding by double digits every year for decades and in some years even over 100% . This expansion, which was first on a tiny scale is now is over 10 GigaWatts/year of new PV and challenging traditional (and environmentally disastrous) technologies for market share.
Even for those of us who study the physics that allow solar PV to work, they are still a little bit magical. First, because they are solid state devices, PV have no moving parts and last a very, very long time. Manufacturers will give you a guaranteed 25 or 30 year warranty, but you can expect them to last at least twice that long losing less than 1% of their power per year. Traditionally PV was made from crystalline silicon, which you can get from beach sand, but through a relatively complicated and costly process. Just as the cost of computers dropped quickly as more computers were built and economies of scale set in – the cost of traditional PV has been dropping quickly. At the same time, scientists and engineers have been experimenting with different PV materials and improving existing devices. For example, amorphous silicon cells decreased the active PV material in a solar cell by more than a factor of 400 to only weigh a gram per square meter! Such “thin film” solar cells are cheaper than what you deposit it on and are now sold commercially on glass, metal or plastic for a dizzying array of applications including roofing materials.
Solar PV also represents an exceptionally egalitarian energy source as almost everyone globally has access to sunlight, which is inherently non-concentrated. Where the vast majority of the population resides there is plenty of sunlight to provide for energy needs with existing solar panels. For example, a house in Ontario, Canada with half of its roof covered with PV can provide its annual electricity needs (Canada is one of the highest per capita users of electricity in the world). Even traditional solar cells could produce as much energy as was invested in their manufacture in less than five years – even in not-so-sunny spots like Canada. Now thin film PV has decreased this energy payback time even more – and thus solar PV technologies can replicate themselves in energy terms by more than dozen times. These self replicating energy devices will eventually drive down the cost of clean renewable energy for all of the world's people – and keep it that way into the foreseeable future.
Solar PV has already reached so called 'grid parity' in a number of locations – meaning that the life cycle cost of the electricity generated from the sun is the same or less than the cost of traditional sources of electricity. This is leading to a virtuous cycle, where the lower costs help more people to afford PV, which improves support for companies, which funds more research, which improves PV performance, which lowers costs of solar electricity, which sparks more demand, which increases the economies of scale, which continues to drive down costs, which opens up even more markets, which makes solar affordable for even more people, and so on. At this point the expansion of PV is essentially inevitable and people of good will can help to accelerate the process.
A sustainable solar powered society for all is our future.
- For historical tracking and current global pricing see: http://www.solarbuzz.com/
- J. Pearce and A. Lau, “Net Energy Analysis For Sustainable Energy Production From Silicon Based Solar Cells”, Proceedings of American Society of Mechanical Engineers Solar 2002: Sunrise on the Reliable Energy Economy, editor R. Cambell-Howe, 2002. pdf
- K. Branker, M.J.M. Pathak, J.M. Pearce, "A Review of Solar Photovoltaic Levelized Cost of Electricity", Renewable and Sustainable Energy Reviews, 15, pp.4470-4482 (2011). http://dx.doi.org/10.1016/j.rser.2011.07.104 DOI and http://hdl.handle.net/1974/6879
- Joshua Pearce, “Photovoltaics – A Path to Sustainable Futures”, Futures 34(7), 663-674, 2002. http://dx.doi.org/10.1016/S0016-3287(02)00008-3