Solar Thermal vs Solar Photovoltaic
Solar-Thermal Tower Seville Spain
An Article in this weeks Economist talks about the potential of Solar Thermal. While a lots of attention is paid to Photovoltaic Solar technologies, it’s older cousin Solar Thermal is also gaining traction.
Solar thermal (See our Glossary of Terms) is a simple concept to understand. Giant mirrors heat a liquid till its boiling point which then drives a turbine. As the Economist puts it:
Simple techniques for concentrating sunlight to generate heat date back thousands of years. In China and ancient Greece, people focused the sun’s rays with mirrors or glass to light fires. In times of war, the same approach is said to have been used to set enemy ships ablaze.
It seems amazingly unsexy!
Unfortunately, sex sells even in engineering. Which brings us to Photovoltaic’s (Glossary of Terms). Photovoltaic Solar (PV) are the “typical solar power” you see on the side of road which power remote signs and calling stations. PV converts sun light directly into energy effectively skipping the middle man (water for solar thermal).
Of course scientists have not figured out how to convert 100% of the energy from the sun into electricity. In fact so far the record for efficiency is around 41%. So it is assumed that with more time and research that PV’s will have more potential as a energy source than the boring solar thermal technology.
Not so fast says the Economist:
(A Solar Expert) believes that solar-thermal power could regain its historical lead over the solar-photovoltaic approach. Competition from photovoltaic systems for large-scale power generation should not be underestimated, however. According to Mr Bullard, thin-film solar-cell modules are rapidly falling in price, and can generate electricity more cheaply than solar-thermal power in some situations. But no matter which approach comes out on top, competition between the two technologies is sure to foster continued innovation, and a growing supply of clean electricity, in the years to come.
It has been assumed the PV will have the equivalent to Moore’s Law for microprocessors. Investors and scientist are hoping that the efficiency rate will double at predictable intervals as the technology matures. (For microprocessors it was every 2 years). But with Moore’s law they were looking at the efficiency and not necessarily the cost structure as this article from Scitizen exlpains:
However the nuances are mischevious. The cost implications of Moore’s Law at heart are built around a constant rate of technology performance improvement (2x transistors every 2 years), implying certain cost improvements. PV’s falling costs curves have had more variables at play. In fact, the real equivalent to Moore’s Law in solar would be to say that cell efficiency or a similiar measure doubles every x years. Most people have tried to apply a Moore’s Law like concept in solar directly to the cost curve, not the technology improvement curve. In fact, the solar costs “Moore’s Law” that seemed the simplest was the idea that every doubling of industry size equaled 10% in cost reductions. But that is not a Moore’s Law, that’s mainly just a description of the supply curve shape and shift, it’s a totally different animal.
But why couldn’t Solar Thermal experience some of the same efficiency gains. And let’s face it making a mirror is cheaper than making a sophisticated PV Array.
Maybe the sexiness of PV is wearing out. Google who seems to excel at the unsexy (just look at their boring homepage) just invested $10 Million in the very solar companies mentioned in the Economist article (eSolar Inc. and BrightSource Energy, Inc). It will be interesting to watch which technology emerges in the next couple of years. Or if both do….
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Neal Dikeman |
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| Filed under : Scitizen >> Technology >> Future Energies >> The REAL Story on Moore’s Law for Solar Key words : cleantech, greentech, photovoltaic, solar, The REAL Story on Moore’s Law for Solar30 Apr, 2009 09:27 am |
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All new industries seem to think they deserve a Moore’s Law. The photovoltaic solar really, really thinks it deserves one, since it kind of sort of looks like a semiconductor business…
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Photovoltaic Moore’s Law Will Make Solar Competitive by 2015, IEEE.org, Understanding Moore’s Law, DistributedEnergy.com, and Silicon Valley Starts to Turn Its Face to the Sun, NY Times.
However the nuances are mischevious. The cost implications of Moore’s Law at heart are built around a constant rate of technology performance improvement (2x transistors every 2 years), implying certain cost improvements. PV’s falling costs curves have had more variables at play. In fact, the real equivalent to Moore’s Law in solar would be to say that cell efficiency or a similiar measure doubles every x years. Most people have tried to apply a Moore’s Law like concept in solar directly to the cost curve, not the technology improvement curve. In fact, the solar costs “Moore’s Law” that seemed the simplest was the idea that every doubling of industry size equaled 10% in cost reductions. But that is not a Moore’s Law, that’s mainly just a description of the supply curve shape and shift, it’s a totally different animal.
EcoEquilibrium 
really good