Amperly: Solar Calculator

Amperly works out your solar system before you spend money on it. Camper van, off-grid cabin, rooftop with a battery or a balcony plant. You see the yield, the battery you need and whether the parts work together.

OFF-GRID SOLAR CALCULATOR
List what you run, like a fridge, lights and a laptop. Amperly sizes the panels, battery bank, charge controller, inverter and wire size. It designs for the darkest month you actually use the system.

CATCH THE WRONG PART BEFORE YOU BUY
• Panel open-circuit voltage in the cold against the controller limit
• Panel voltage in the heat: is it still high enough for the controller to charge
• Panel short-circuit current and charge current against the controller rating
• Battery charge, discharge and peak current against its datasheet
• Inverter power and the startup surge of a fridge or a pump
• Fuse and wire size chosen together, with voltage drop
• LiFePO4 batteries that must not be charged below freezing
• Battery bank wiring in series and parallel
If a datasheet value is missing, Amperly says "not checked". It does not guess.

REAL SUN DATA FOR YOUR PLACE
Type a town, pick the panel tilt and the direction it faces. Amperly loads monthly irradiation from PVGIS, run by the European Commission, and temperatures from NASA POWER. Only rounded coordinates leave your phone.

SEE HOW EVERY NUMBER WAS MADE
Every result comes with its math. You see where each voltage, current and wire size comes from.

NO ACCOUNT, NO ADS
Amperly calculates offline. Your systems stay on your phone.

FREE AND PRO
Free: every check and warning, 1 saved system, 10 components of your own.
Pro: unlimited systems and components, a PDF report with a shopping list, all three cable runs. A one-time purchase, no subscription.

Amperly does not replace an electrician. Have a qualified person check the wiring before you connect anything.

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Recent changes:
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