Solar
Commonweath SolarII reqs
Interconnection Agreement. A separate application must be submitted to the electric utility to start the formal interconnection process, and sufficient lead time should be allowed, based on time frames listed in the Interconnection Tariff (see link below). All PV projects must have an appropriate electric utility interconnection agreement in place at the time of interconnection to the utility grid.
small inverters
Enphase microinverter UL approved $150+32(connector) 220 watt
calculator
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 < $3.00/watt.
"PVWATTS v.2: AC Energy and Cost Savings" "Station Identification" "Cell ID:","0274366" "State:","Massachusetts" "Lat (deg N):", 42.37 "Long (deg W):", -71.03 "PV System Specifications" "DC Rating:"," 1.0 kW" "DC to AC Derate Factor:"," 0.770" "AC Rating:"," 0.8 kW" "Array Type: Fixed Tilt" "Array Tilt:"," 30.0" "Array Azimuth:","180.0" "Energy Specifications" "Cost of Electricity:","16.6 cents/kWh" "Results" "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)" 1, 2.79, 69, 11.46 2, 3.60, 80, 13.29 3, 4.59, 109, 18.11 4, 4.79, 108, 17.94 5, 5.39, 120, 19.94 6, 5.50, 115, 19.11 7, 5.45, 117, 19.44 8, 5.34, 116, 19.27 9, 4.83, 104, 17.28 10, 3.97, 91, 15.12 11, 2.72, 62, 10.30 12, 2.43, 59, 9.80 "Year", 4.29, 1150, 191.06
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.
=1KW inverter
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
about charge controllersa 555 charge controller
