Free interactive tools
Off-Grid Power Tools & Calculators
Sizing an off-grid system by hand is where most beginners get stuck. These free tools do the thinking for you. Answer a few simple questions and walk away with real numbers and a parts list you can actually buy.
Off-Grid System Builder
Pick your use-case and budget, and get a complete, copy-and-buy parts list. Panel, battery, inverter, charge controller, and the extras that tie it all together.
Build my list →Off-Grid Solar Calculator
Tell us your daily power use and we will size your solar array, battery bank, and inverter. Simple inputs, instant results, no math headache.
Size my system →Run-Time Calculator
Pick your appliances and battery size and see how many hours you will really get. Inverter losses and realistic draws are already baked in.
Check my run time →Wire Size Calculator
Amps, cable length, and voltage in. The right AWG gauge out, with voltage drop shown and the fuse size that protects the wire.
Get my gauge →More tools are on the way, including a battery bank series and parallel wiring helper. Check back soon, or start with the four above.
Frequently Asked Questions
Are these tools free?
Yes. Every tool here is free to use, with no sign-up. If you buy gear through our links, we may earn a small commission at no extra cost to you, and that is what keeps the lights on.
Do I need any electrical experience?
No. The tools are written for total beginners. You answer a few plain-English questions and we handle the sizing math and the part picks for you.
How accurate are the results?
They give you a solid, real-world starting point. Your exact needs depend on your climate, how you use power, and the gear you choose, so always treat the numbers as a smart estimate and size up if you live somewhere cloudy.