EasySolarCalculator. Is Off-Grid Solar Panel System Calculator designed to make easy calculating Off-Grid Solar System. The calculator uses your daily energy demand or system load to determine the size of solar panel, Battery Bank, Charge Controller, Inverter, and Solar Panel wire Gauge size you will need. All you need is to fill out each field for each appliance quantity, power (watts), and how many hours being used during day. The app will calculate your energy demand in watts and watt-ho