Solar Savings Calculator

Enter your solar system size, local conditions, and cost to find your annual savings and payback period.

Solar Savings Calculator

Live

System size (kW)

Peak sun hours/day

Electricity rate ($/kWh)

System efficiency (%)

Total system cost (optional, for payback period)

Estimated annual savings

$1,314.00

Annual production

8,760 kWh

Payback period

13.7 years

A general estimate - actual production depends on your specific location, panel orientation, shading, and local incentives, which vary widely.

The formula

Annual production (kWh) = System size (kW) x Peak sun hours/day x 365 x Efficiency Annual savings = Annual production x Electricity rate Payback period = System cost / Annual savings

Example

A 6kW system, 5 peak sun hours/day, 80% efficiency: production = 6 x 5 x 365 x 0.80 = 8,760 kWh/year, savings at $0.15/kWh = $1,314/year. At an $18,000 system cost, payback ≈ 13.7 years.

Step-by-step guide

Enter your solar system's size in kW (check your quote or existing system spec).
Enter your area's peak sun hours per day (a solar installer or online solar map can provide this for your location).
Enter your electricity rate and, optionally, total system cost to see your payback period.

Why "peak sun hours" isn't the same as daylight hours

Peak sun hours represent the equivalent number of hours per day the sun would need to shine at its strongest intensity to produce the same total energy your location actually receives - not simply how many hours the sun is up. A location might have 14 hours of daylight but only 5 peak sun hours, because sunlight is far more intense at midday than at dawn or dusk. This is why peak sun hour maps (widely available for different regions) are the standard input for solar production estimates, rather than simple day-length figures.

Common mistakes

Using total daylight hours instead of peak sun hours - this significantly overstates expected production, since it ignores the lower intensity of morning and evening sunlight.

Ignoring available tax credits or rebates when calculating payback period - many regions offer incentives that meaningfully reduce the effective system cost and shorten the real payback time.

Frequently asked questions

Where do I find peak sun hours for my location?

Government solar resource maps and most solar installers can provide this figure for your specific region - it varies significantly by latitude and local climate/cloud cover.

What does "system efficiency" account for?

Real-world losses from panel temperature, inverter conversion, wiring, dust, and imperfect sun angle typically mean actual output is lower than a panel's rated capacity - 75-85% is a commonly used efficiency range for estimates.

Does this account for electricity rate changes over time?

No - this uses your current rate held constant. Since electricity prices have historically tended to rise over time, actual long-term savings may end up higher than this estimate if rates increase.

Related calculators

See the full list of Engineering calculators, or try: