About SolarCalc.fyi

SolarCalc.fyi is a free planning tool operated by BestChain Inc. It helps you estimate the solar panels, battery capacity, inverter capacity and charge controller size needed for an off-grid project. No account is required to use the calculator.

How the calculator works

Start with the appliances you plan to use, their wattage and their daily operating hours. The calculator combines these inputs with peak sun hours, your battery settings and sizing assumptions to produce an initial estimate.

Solar resource data is requested from NREL when available. If the request is unavailable, the calculator uses a location-based estimate or a default of 4.5 peak sun hours. Actual output varies with season, shade, orientation, weather and equipment losses.

What the results mean

Results are estimates for comparing options and preparing questions for an installer. They are not an electrical design, installation quote, code compliance assessment or guarantee of performance. Check appliance labels and starting surges, winter conditions, equipment compatibility and local installation requirements before purchasing.

Cost estimates are indicative and do not deduct tax credits. Equipment links are candidates to investigate; they are not a complete, verified system kit. Current prices and availability are shown by the retailer.

How this free tool is supported

As an Amazon Associate we earn from qualifying purchases. Some equipment links are affiliate links: a qualifying purchase may earn us a commission at no additional cost to you.

Explore the tool

Try the calculator, read the FAQ, or review our references and privacy policy.