Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Solar Panel System Sizing Calculator

Size a rooftop solar PV system from your real electricity usage, local peak sun hours, system losses, and your target offset — and get the number of panels you actually need.

Average monthly electricity use (kWh)

Peak sun hours (daily average) (h/day)

Share of usage to offset (%)

System losses (inverter, wiring, soiling, heat) (%)

Panel power rating (W)

Solar Energy

Solar Savings Calculator

Calculate monthly bill savings from a solar PV system by multiplying solar production by your electricity rate. Use it to estimate the financial benefit of an installed or planned system month-by-month.

Monthly Solar Production (kWh)

Electricity Rate ($/kWh)

Key differences

	Solar Panel System Sizing Calculator	Solar Savings Calculator
Category	Solar Energy	Solar Energy
Inputs required	5	2
Result	Solar panels needed (panels)	Monthly Savings ($)
What it does	Size a rooftop solar PV system from your real electricity usage, local peak sun hours, system losses, and your target offset — and get the number of panels you actually need.	Calculate monthly bill savings from a solar PV system by multiplying solar production by your electricity rate. Use it to estimate the financial benefit of an installed or planned system month-by-month.