Solar

Actual vs rated power

For wind turbines the industry average installed cost is about $2 million per megawatt, about $2.00/watt. Over the course of a year, however, a turbine produces only about one-third of its theoretical maximum capacity So it costs about $2/1/3watt or about $6/useful_watt. Run for a year each watt of capacity produces 24*365/1000 or 8.76kwH of electricity which priced at $.16/kwh creates about $1.40 worth of electricity. Simple payback in 6/1.4 or 4.3 years.

Solar PV in Boston on the other hand, if it did cost $2/watt,

Commonweath SolarII reqs

Approved Equipment Lists

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 M215 microinverter UL approved $150+32(connector) 220 watt on the approved equipment list

plugs into wall 1000 watt $253 not UL approved

Sunteams 1500 (240 Vac) $699 1500 Watt Solar Grid Tie Inverter, UL & CEC Approved on the approved equipment list has reporting display]

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.

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

hot water

~30 therms/mo

DIY panels

10w 12v mounts to panel $59

about charge controllersa 555 charge controller

diy instructions

tabbing wire flux pen bus wire diodes

epoxy]