Renewable Energy Calculators

Battery Backup Calculator

Calculate required battery backup capacity in watt-hours and amp-hours from load, backup hours, voltage, depth of discharge, and efficiency.

Biomass Energy Output Calculator

Calculate usable electrical energy output from a quantity of biomass fuel based on energy density and conversion efficiency.

Energy Storage Cost Calculator

Calculate battery storage cost per kWh and levelized cost of storage over the battery's lifetime from total cost, capacity, and cycle life.

Geothermal Borehole Depth Calculator

Estimate the required borehole depth for a ground-source geothermal heat pump system based on required heating capacity.

Geothermal Heat Pump Calculator

Calculate geothermal heat pump heat output and energy savings versus resistance heating from electrical input and coefficient of performance.

Hydropower Output Calculator

Calculate hydropower output in kilowatts and annual energy in kWh from water flow rate, head height, and turbine efficiency for site assessment.

Net Metering Calculator

Calculate the net solar bill or credit from energy generated, energy consumed, and separate grid import and export electricity rates.

Off-Grid Battery Bank Amp-Hour Calculator

Calculate required battery bank amp-hour capacity for an off-grid solar system based on daily energy needs, autonomy days, and depth of discharge.

Off-Grid System Size Calculator

Calculate the solar panel wattage and battery capacity needed for a complete off-grid power system from daily load, sun hours, and autonomy days.

Solar Array String Sizing Calculator

Calculate the valid range of panels per series string for a solar array based on panel voltage and inverter input voltage window.

Solar Carbon Offset Calculator

Calculate the annual CO2 emissions offset by a solar installation based on energy output and the local grid's emissions factor.

Solar Inverter Sizing Calculator

Calculate a recommended solar inverter size using the standard DC-to-AC oversizing ratio applied to total panel wattage.

Solar Panel Output Calculator

Calculate daily and annual solar panel energy output from panel wattage, panel count, peak sun hours, and system efficiency for accurate sizing.

Solar Panel Size Calculator

Calculate the solar system size in kW and number of panels needed from daily energy usage, peak sun hours, and system efficiency.

Solar Panel Tilt Angle Calculator

Calculate the optimal solar panel tilt angle based on your latitude, with seasonal adjustment for summer or winter optimization.

Solar Payback Period Calculator

Calculate solar payback period in years and months from system cost, incentives, and expected annual electricity savings for a clear return timeline.

Solar Shading Loss Calculator

Calculate actual solar energy output after accounting for shading losses from trees, buildings, or roof obstructions.

Wind Turbine Capacity Factor Calculator

Calculate a wind turbine's capacity factor, comparing actual energy output against its theoretical maximum rated output.

Wind Turbine Output Calculator

Calculate wind turbine power output in kilowatts from blade radius, wind speed, air density, and power coefficient using the standard wind power formula.

Wind Turbine Swept Area & Power Calculator

Calculate a wind turbine's rotor swept area and theoretical maximum power output using the Betz limit.

When Clean Energy Actually Pays for Itself

Renewable energy systems — solar, wind, geothermal — all carry a significant upfront cost that only makes sense once you know how long it takes to earn back through savings. These ten calculators cover sizing and payback math for renewable systems.

Finding Solar Payback Period, Step by Step

Get the total installed system cost. Include equipment, installation, and permitting, after any tax credits or rebates are applied.
Estimate annual electricity bill savings. Based on system output and your local electricity rate.
Divide cost by annual savings. A $20,000 system saving $1,500 a year gives a payback period of about 13.3 years.
Compare against the system's warranty life. Most solar panels carry 20-25 year warranties, so a payback period well under that leaves many years of largely free electricity afterward.

Run your own numbers with the Solar Payback Period Calculator, and check output potential first with the Solar Panel Output Calculator.

Popular Renewable Energy Calculators

Net Metering Calculator — estimates credit earned for excess solar power sent back to the grid.
Battery Backup Calculator — sizes battery storage capacity needed to cover a target outage duration.
Off-Grid System Size Calculator — sizes a complete off-grid power system from household energy needs.