I recently came across a great article discussing solar photovoltaic (PV) efficiency. You can read it in its entirety on this website - here’s the gist.
When people hear that the typical efficiency for solar power is somewhere around 15%, or even as low as 12% for organic photvoltaics, they scoff and start to mumble that this is much to low to be efficient. Usually, most people justs say that they’ll wait until the numbers start to go up – but this is a trap; why?
Well, you’ve probably heard of over 40% efficiency in lab tests and space travel, and therefore you think that 15% is just too low to even consider. But perhaps you drive a car; just a typical, average, car. The efficiency is around 15–25%, for a finite resource that pollutes. Should we wait for better?
Maybe you don’t know, but in some ways, you’re similar to a car – you get your energy from fuel too, except your fuel is called food; and guess what? your body’s efficience is about as good as a car’s. Are you a fan of biofuels? Ow man, you really shouldn’t! By now, we already know that there’s many messed up things with biofuels, and traditional ones only go up to 2% efficiency! The much praise algae fuel goes up to 6%. Even photosynthesis, nature’s way of using the solar energy only goes for 6% – so it’s quite remarkable that in a few decades, we managed to outperform nature by a factor of almost 3!
Ok, what the article I told you about doesn’t discuss one thing – it takes a lot to produce efficient solar panels. The high purity silicon and indium are valuable resources, and they’re not that cheap. However, the alternatives also take valuable resources to build – and we’re talking about a ubiquitous renewable energy source.
But if you really want to wait for the next big thing what’s great, and I mean great as in the next big thing – are organic photovoltaics. They have slightly lower efficiency at about 12%, but they’re much more eco friendly, and while expensive at the moment, will go to reasonable prices in just a few years
Andrei's background is in geophysics, and he published his first scientific paper when he was still an undergrad; now, his main focus is on how geology and geophysics can be applied to understand and protect the environment. Feeling that there is a gap between scientists and the general audience, he started ZME Science - and the results are what you see today. 
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Published on Tue, Jan 22, 2013 by Mihai Andrei
Post filled in: Environmental Issues, Renewable Energy