12V Install Tools & Testers

Solar & Charging Check

See whether your solar and DC-DC charging could put back what you use each day, and roughly how much solar would balance it.

This gives a daily energy-balance estimate only, not a complete system design. Enter your numbers, check the assumptions, and see whether your charging could keep up. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. Daily energy demand

Work this out first with our Daily Energy Use & Battery Size Calculator, then type in its Daily energy use (from battery) figure, which already includes estimated inverter losses. The two pages don't share data, so enter the number here yourself.

Required. 0 to 100,000 Wh/day.
Used for the DC-DC estimate and Ah equivalents. These are nominal voltages; actual battery voltage varies with chemistry and conditions.

2. Solar array

Peak sun hours are the equivalent number of hours of full-strength sun your panels receive in a day. They are an estimate for the particular location, season, panel angle and shading you're planning for, so use a figure that suits your trip. The defaults below are illustrative assumptions only, not recommended values for any location.

Add up the rated watts of all panels. Illustrative default: 200W.
Your estimate, 0 to 12. Illustrative default: 4, not a local value.
Allowance for heat, dust, angle, cabling and controller losses, 0 to 100%. Illustrative default: 25%.

3. DC-DC charging (optional)

Enter the current you actually expect to flow into the battery, not just the charger's maximum rating. Real output varies with battery state of charge, temperature, alternator behaviour, the charging profile and operating conditions.

Expected average output, 0 to 500A.
0 to 24 hours.
Leave at 100% if the amps above are already the output into the battery. Lower it only for extra losses not already counted (10 to 100%).

4. Results

How it was worked out

    What this does and doesn't tell you

    • This calculator estimates daily energy balance only. It does not guarantee that your battery will fully recover, that your gear will run without interruption, or that your system is safe. It is not a complete system design, wiring specification or safety assessment.
    • Weather, seasonal changes, shading, panel temperature, charge-controller limits, battery charge acceptance, cable losses and other system constraints can materially change real results.
    • It doesn't work out how many days your battery will last in a shortfall. That needs your battery's usable energy, not just its nominal voltage. Use the battery calculator to size storage.
    • Any work on 240V AC wiring, including inverter outputs, mains inlets and shore power, must be done by a licensed electrician.

    Next steps

    Compare panel types in Solar Blanket vs Rigid Solar Panel, size your charger with What Size DC-DC Charger Do I Need?, and see how it all fits together in the Calculate & Size Your System section of our Build Your System guide.

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