How long does it take for in home energy storage to lay itself off?
n general solar thermal applications will pay for themselves faster than solar photovoltaic panels. This is because although photovoltaic panels in the lab have achieved efficiencies of around 40%, the ones you buy only achieve around 14%. Solar thermal panels can be 60 to 80% efficient. The technology is hundreds if not thousands of years old and much cheaper. The solar thermal vacuum tube collectors will work on cloudy and cold days. But governmental and utility incentives help to bring down the payback period of photovoltaic as well. In general the more use you make of a photovoltaic system the quicker the pay back period. So it may not be cost effective to put in a geothermal heat pump and power it with photovoltaic. Cheaper electric resistance heat seems to work better. With solar thermal cost will rise as you go from 80% to 100% usage. Depending upon the alternatives an 80% capacity system may pay back better than a 100% system. Solar thermal: Hot water systems can have pay back
