Solar Energy Calculators
Last updated: October 2026
Solar Savings Calculator
Calculate monthly bill savings from a solar PV system by multiplying solar production by your electricity rate.
Solar Panel Angle Calculator
Find the ideal tilt angle for your solar panels based on your latitude, season, and roof pitch.
Net Metering Calculator
Estimate your monthly electric bill or credit with solar under time-of-use net metering: peak and off-peak rates, when you produce and use power, export credit and fees.
Solar System Sizing Calculator by US Region
Get a quick solar array size in kilowatts by picking your US region's typical peak sun hours (3.5 h northern states to 6.5 h southwest desert) and an 80β110% usage offset.
Simple Net Metering Calculator (Flat Rate)
Calculate your monthly electric bill or credit with solar under simple, flat-rate net metering: surplus kWh credited at a share of the retail rate, shortfall bought at retail, minus a fixed monthly fee.
Solar Inverter Sizing Calculator
Size the inverter for a solar array from its DC panel capacity and your chosen DC:AC ratio (inverter AC rating = DC watts Γ· ratio), with guidance on which ratio suits your roof orientation and climate.
Solar Carbon Offset Calculator
Estimates the annual CO2 emissions avoided by your solar PV system, using your yearly production in kWh and the grid emission factor it displaces.
Solar Panel System Size Calculator (Your Sun Hours)
Determine how many kilowatts of solar panels you need from your monthly kWh, the exact peak sun hours for your address (from a solar map or PVWatts) and an offset goal from 50% to 110% of your bill.
Solar Financing Calculator
Estimate the monthly payment and total interest on a solar panel loan from the system cost, down payment, rate and term, and compare it with your electric bill.
Solar Panel Efficiency Calculator
Computes the operating efficiency of a solar panel from its measured output, surface area, and incident irradiance.