Off-Grid Solar Sizing Calculator
"What size solar kit do I need?" depends entirely on what you run and where you park. Enter your daily use and explore an initial array, battery and continuous-inverter scenario.
Illustrative efficiency and depth-of-discharge assumptions. Array sizing uses the entered overall delivery efficiency. Battery sizing separately includes inverter efficiency. The 25% continuous-inverter margin does not establish surge capability or a safe equipment design.
How the math works
array watts = daily Wh ÷ sun hours ÷ overall efficiency battery Wh = daily Wh × days of autonomy ÷ usable depth ÷ inverter efficiency battery Ah = battery Wh ÷ system voltage inverter watts = largest simultaneous load × 1.25
Frequently asked questions
How should I estimate the array?
Measure daily appliance energy and use local peak-sun hours for the design season. The efficiency input accounts for total losses between panel output and delivered energy. Shade, winter conditions and recharging after a cloudy spell can require more capacity.
How should I estimate batteries?
Enter the desired days of autonomy and check the battery maker's allowable depth of discharge. The displayed chemistry choices are illustrative usable fractions, not universal battery specifications.
Does the inverter result handle starting surges?
No. It is a continuous-power scenario with 25% margin. Separately check starting watts, surge duration, voltage, power factor and battery discharge capability for the actual equipment.
Is this a complete system design?
No. Wiring, protection, controller sizing, battery temperature behavior, standby consumption, seasonal recharge and backup power require a system design based on the equipment and site.
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