Solar
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A KW worth of panels will produce about $190/year of electricity on my roof. In 15 years that's about $3000 worth of electricity so to break even you need installed cost to be < $3.00/watt.
If you could install a 1KW system at $2.00/watt you make a return of about $66/yr or $66 on a $2000 investment or about 3.3% annual interest on your investment.
02130 calculator At 30 degree tilt the average solar is <math>4.29\frac{kWh}{\frac{m^2}{day}}</math> The bedroom roof would probably produce around $220/year at $.15/kwH
existing use
heat
hot water
~30 therms/mo
electrical
DIY panels
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