Solar Calculator

Solar Calculator

Estimate solar installation cost, annual savings, CO2 reduction, payback period, and IRR.

You will need a recent utility bill for this tool.

Solar Inputs

Name

Email

Usage kWh/year

Enter your annual consumption from your utility bill in kWh.

Solar Zone

Enter the solar zone you live in from the solar zone map.

Zone 1 — 3.9 Zone 2 — 4.15 Zone 3 — 4.4 Zone 4 — 4.65 Zone 5 — 4.9 Zone 6 — 5.15 Zone 7 — 5.4 Zone 8 — 5.65 Zone 9 — 5.9

Roof Exposure

Enter the approximate direction your roof faces.

South — 1.00 East/West — 0.65 Between — 0.90

Electric Rate ($/kWh)

Enter the electrical rate in $/kWh from your bill or utility website.

State/Local One Time Incentive

Enter any state or local incentive for solar installation.

State/Local Annual Incentive

Enter any state or local annual rebates for solar.

Electricity Source

Choose which fuel source you want to base your electrical generation on. Either find your subregion on the eGrid map or use natural gas or coal.

Interest / Discount Rate %

Choose the interest or discount rate you would like to use.

Electricity Inflation %

Choose the inflation rate for electricity prices you would like to use.

Analysis Years

Default values match the spreadsheet example: 12,000 kWh/year, Zone 3, East/West roof, $0.19/kWh.

Solar Zone Map

Use the NREL kWh/m²/day bands on the map to choose the closest calculator zone below.

Zone 1 — 3.9 Zone 2 — 4.15 Zone 3 — 4.4 Zone 4 — 4.65 Zone 5 — 4.9 Zone 6 — 5.15 Zone 7 — 5.4 Zone 8 — 5.65 Zone 9 — 5.9

Map source: NREL / National Solar Radiation Database, U.S. Annual Solar GHI.

Recalculate Download PDF

Adjust inputs to update the model, then export the report.

Installation Cost $0

Annual CO2 Saved 0

Payback Period N/A

IRR% N/A

Solar Results

Approximate # of Panels	0
Annual Electricity Savings	$0
CO2 Reduction / Investment	0

25-Year Cash Flow

Year	Cash Flow	Undiscounted Balance	PV of Cash Flow	Discounted Balance