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Solar Cells Optimized

Combine your Photovoltaic Cells with Solar Heat
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Current photovoltaic cells are fairly inefficient, maximum efficiency is at about 25% with the rest lost as heat. (I know some recent news has researchers playing with gallium nitride and such, and maybe getting closer to 50 -70%, but they're not just around the corner...) Why not stack the electric solar cells onto a solar heat collector to scavenge the heat? In small sq footage areas (townhouse roofs, condos, etc) one of these combo cells could make solar a good supplemental heat/electrical source.
MacGuyver, Jun 27 2007

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       Why not? I've often wondered this myself. [+]
nuclear hobo, Jun 27 2007
  

       There has been some research done on this, with improved efficiency figures. I think the problem is the tradeoff between the PV and thermal outputs and the capital cost when this kind of thing goes to market... bear in mind that a current 'hot water only' system takes 6-8 years to pay for itself, and PV cells are £5 per coffee mat with an output (at midday in July/August) of 1000W/m2 * 0.1m *0.1m * 0.2eff = 2W, so £2.50 for a watt before the clouds come! You need about 4m2 of thermal panels for reasonable hot water performance... that comes to £2,000 before the fitting costs!   

       So the customer pays £5,000 instead of £2,500 for an increace from 60% to 65% system efficiency (the thermal side takes a bit of a knock from the solar panels)!   

       The idea is good, and has been tried, but the market just isn't ready, maybe when GaAs cells are half that price, it'll be reasonable.   

       Bun all the same!
Skrewloose, Dec 05 2008
  

       I thought electrons / photons loved the cold to do their tricks . The obvious goal would be to lose the heat not select fot it .
wjt, Dec 06 2008
  

       The drying of green lumber might be a good application for both solar technologies in hybrid or side by side. If dried too quickly the wood cracks. If too slow you lose time in getting to market.   

       The electric part could manage fans, doors, humidity, and phone for help when in need. The heat part could help accelerate things when advisable.   

       Robots to paint the barns black and clean the glass of the collectors might be another plus.
popbottle, Jan 04 2014
  
      
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