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Combined solar hotwater/electricity

 
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Using the right design, it may be possible to create solar hot water system that shunts a portion of the heat into spinning a turbine.

[solar hot water panel] ->[hot water tank]-> [steam] -> [generator]

Alternatively it could in the style of a mini 'solar thermal power plant' that shunts some heat into a heat exchanger for hot water.

[solar thermal power plant panel] -> [ shunt to electric generator] -> [ heat exchanger] -> [hot water tank]

The last approach appears to be better as between the solar power plan panel and the heat exchanger, we can use liquids that can store more heat.

The pros:

-Better use of space as the same solar hot water system is being used to generate electricity. -Possibly better efficiency as silicon tech is not yet as efficient compared to driving a mechanical generator. -May be cheaper than buying solar hot water and solar panels combined.

Cons:

- More complexity - May cost more (depends) - Water may have to be stored pretty hot

mofosyne, Dec 31 2011

(?) Baked http://www.nuenergy...egrated/solarcombi/
[infidel, Dec 31 2011]

Again http://www.energyma...icle&article_id=806
[infidel, Dec 31 2011]

[link]






       It's in the links, [Simpleton]. Try the second one first.
infidel, Dec 31 2011
  

       simpleton: Hmmmm... Good point? Well would changing the idea to make it a mini solar power plant that shunts some energy to heating water be a better idea? It can be done as part of a heat exchanger allowing us to regulate how hot the water can be. Might make the system more simpler.   

       I'll shall add that to the idea now   

       infidel: We are trying to avoid the use of 'photovoltaic' as its not very efficient.
mofosyne, Dec 31 2011
  

       Use the heat to warm water and draw off some of the energy using Peltier devices.
infidel, Dec 31 2011
  

       Peltier devices are not very efficient as well compared to a standard dynamo
mofosyne, Dec 31 2011
  

       Photovoltaics are as efficient as quite a lot of gasoline engines.
infidel, Dec 31 2011
  

       really? I personally haven't heard of that infidel. From the last time I heard, was that photovoltaic efficiency was less than 20%   

       vs   

       "the maximum efficiency is only around 80% for the best of these generators—60% is more typical" according to "Electric_generator" in Wikipedia
mofosyne, Dec 31 2011
  

       Very expensive PV can run upwards of 40% efficient, the Carnot (theoretical maximum) efficiency of a gasoline engine is maybe 60%.   

       A typical production PV cell is maybe 10-15%, a typical car engine is maybe 20-40%.   

       That is an absolutely horrible way to look at it though. In a car, you are paying for the fuel, so efficiency matters. In a PV setup, the fuel is free, so initial cost matters. Efficiency only matters when we start running out of space.
MechE, Dec 31 2011
  

       You're looking at this backwards: just rig a solar collecter- type generator to run its cooling cycle through the water heater. The oil has to cool down anyway, why not recover the heat?
Alterother, Dec 31 2011
  

       I based my comment on the fact modern commercial PV cells are at 18-20% and the bulk of cars are still in the range of 20% efficiency. There are more efficient cars, certainly. There are also more efficient PV cells. It's a matter of cost and time as to how it will settle out.   

       You also have to consider, as [MechE] pointed out, the sunk cost of PV vs gasoline energy usage, as well as the ongoing fuel cost.   

       [Akimbo], I recommended Peltier devices and PV largely because there are no moving parts and therefore much lower maintenance costs. Most of the work you'll have to do after the event is involved in cleaning the units to maintain efficiency.
infidel, Dec 31 2011
  

       This is a poorly constructed idea, using poorly constructed language. The subject has been covered extensively, can we please move on?
bs0u0155, Jan 01 2012
  
      
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