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Q & A: solar electrical power

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Most recent answer: 12/07/2011
Q:
Everyone knows solar cells are used to convert sun light into electricity. Is there a different method which converts sun light to electricity without using solar cells, heat transfer or chemicals for the transfer?
- Tim Kenneally (age 48)
Tampa, Florida
A:
Sort of, but not any important one I can think of.

1. Pretty much any direct conversion system would be called a solar cell.

 The other two main methods are:

2. biofuels: Plants convert sunlight energy to high-free-energy chemicals (e.g. sugar), which are then typically burned in power plants to generate electricity. This would fall in your "chemical" category, as would any versions that replaced the plants with some artificial systems.

3. concentrated thermal systems. These use mirrors to focus the light on a large boiler that gets very hot, driving turbines directly without the intermediate chemical step. In some systems the heat can be stored and used to provide power overnight. Spain has pioneered the use of these sorts of systems. However, these fall in your "heat" category.

Maybe this next one doesn't quite fall in any of your categories: Let the light heat up some electrical resistor. That increases the voltage noise in the resistor. Couple it through vacuum capacitors to cooler rectifying diodes. Their output will have some dc current. However, I suppose you could say that this too was a form of heat transfer, or you could even call it a solar cell of sorts. It's also highly impractical.

Mike W.

(published on 12/07/2011)

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