I'll post key stories, links, blogs, resources, and comments, and offer my own commentary on solar energy-related issues. Discussion is definitely encouraged and welcome. Please sign the guest book and comment!

"On Solar Cells" © James K. Bashkin, 2008

All solar cells work in basically the same way (there are really two basic ways, but the technicalities aren't important to this discussion, at least yet).

Semiconductors are the key, and these materials are characterized primarily, to a first approximation, by their composition (like gallium arsenide or indium phosphide) and band gap. The band gap can be thought of as the amount of energy, such as the energy supplied by a photon (light), that is required to promote an electron from the nonconducting valence band to the conduction band. Quick definition: photon, or particle of light, refers to the particle side of light's wave-particle duality.

Manufacturing techniques can vary significantly for solar cells (solar panels), some being very complicated, involving the careful growth of crystals on top of other crystals under high vacuum conditions, and other techniques being as simple as spraying or painting a few payers of paint or ink. A lot of clever invention went into all of these designs.

One important idea relevant to this discussion is Einstein's photoelectric effect. However, photocells were discovered experimentally before the photoelectric effect was proposed, and the photoelectric effect was actually proposed theoretically before equipment was good enough to prove it was true, experimentally. I realize this sounds like a circular argument, and it would be if the photoelectric effect and photocells were exactly the same the thing, but they aren't. The photoelectric effect describes how light can eject electrons from metals and other substances. Photocells are made of nonmetallic semiconductors that are not conductors but can be turned into conductors under the influence of absorbed photons. For photocells, light doesn't eject electrons but causes charge to flow, or electricity to be generated and conducted through the material.

One of the design issues is how to make photocells that use the solar spectrum efficiently. This is one of the reasons why a variety of materials and approaches are used, and often combined. to give a final panel design. It also helps explain why photocells for satellites have different requirements than photocells for earth: the atmosphere around earth absorbs light, as you know, and this changes the available solar spectrum vs. what is available in space.

Once a semiconductor absorbs a photon (or several), it becomes a conductor. However, the efficiency of charge conduction (electrical conduction) is related to things like how many so-called charge carriers are available, the mobility of these charge carriers through the material, and to the ability of the material to avoid what is called recombination, where the + and - charge recombine, giving off heat and no electricity, and therefore waste the absorbed photon.

Much of the elegant design of natural photosynthetic systems has evolved to maximize efficiency and minimize nonproductive recombination.

Does any of this help?

Note to cherished physicists, chemists, et al., please offer corrections if you like, but please consider that I will make this continuing discussion more sophisticated over time, with additional installments and even references/literature citations! So far, it is just off the top of my head, as it were. I would appreciate it if you would distinguish between oversimplifications and true errors. The latter I'm glad to hear about while the former is here on purpose, to help people without technical training develop some sense of how solar cells work. JKB

"California based Bio Solar has a different slant on making solar cells ... rather than focusing on improving the efficiency they focus on reducing the cost and using non petroleum based materials."
Click to read the article at GreenTechnoLog

Click to read the article at Ecofriend, where I saw it first (via InstaBlogs.com)

"In discussions about global warming, many are reluctant to make 'the first move'. The coal industry points at figures by the Energy Information Administration (EIA), showing that coal accounted for 'only' 39% of the world total carbon dioxide emissions in 2004, while emissions from oil were larger. In reply, the oil industry points at EIA projections that coal looks set to become the largest energy source by 2010."
Click to read the full article.

As reported by AlwaysOn and Chemistry for a Sustainable World, a press release announced that eSolar has raised $130 million with the help of Google and other investors. eSolar makes solar-based power plants, and it is great to see this investment even when the economy is suffering, because it is so important for our future.

1.1kW Grid-Tied Solar Electric System - $ 7503.00
GoGreenSolar.com 1.1kW grid-tie PV power systems are designed for use on residential and small commercial buildings. They consist of high quality Evergreen (PV) modules, a Kaco inverter, array wiring, DC and AC disconnects, UniRac mounting structures to secure modules on the roof, electrical drawings, data sheets, warranties and instructions. Solar Electric Photovoltaic starter system can be combined to form larger systems to meet your requirements, in the future. The GoGreenSolar.com starter system can reduce part of your bill, or eliminate higher cost electricity in locations that have progressively increasing rates as consumption increases. The starter kit system gives you all the benefits of utility interconnection and net metering for a low upfront investment. This kit qualifies for rebates and tax credits depending on the state you live in.

Thanks to legbamel for his encouragement- check out Urban Sprawl and the Environment.

Since I have a love of the arts, literature and music in addition to my strong feelings about the environment, I was delighted to find lensmaster, Classic, who is prolific and a pleasure to read. Read Classic's lens Albatross, for example!

For more about what I'm up to: I operate at DIGG, Reddit, bloggingzoom, blogcatalog, gather.com and a few other sites I can't think of now under the name chemrat. My main blogs are Nearly nothing but novels: fiction and crime fiction book reviews and Chemistry for a sustainable world. There is some good environmental discussion in the comments at gather.com, along with good articles by many (SamCarana and Steve B. being two who have a lot of specific information on energy issues).

I am excited about a new service, GoGreenSolar, which operates all over the US and in many parts of the world, that helps you find installers of solar and wind power, including competing bids, and gives lots of detailed advice on the various choices and tax rebates. It works based on your zip code/post code, along with specific information about your home or other building of interest. I bring it up here because I have had countless requests for specific information and advice about installing solar power, both solar heating and solar panels for electricity.

I have a strong statement to make about alternative energy. I find that it is easy to make the case for moving away from carbon-based energy sources (coal, oil, natural gas) for reasons of pollution, health and global stability without referring to Global Warming. I say that not because I dispute Global Warming (quite the contrary), but because I've found many people who are emotionally invested in various anti-Global Warming positions (as in GW is a conspiracy of "left-wing anarchists"). However, these same people will in many cases completely buy into the idea of alternative energy for reasons that air pollution, toxic waste, war, and many other problems can be attributed to fossil fuel use.

I'd be very interested to hear any comments on these thoughts. Thanks.