CEG calculator

Solar battery sizing and autonomy CEG

LiFePO4 DoD 90%. CEG sizes: 16 kWh EVE, 17 kWh MB31 or CATL, 34.20 kWh Option 2.

CEG LiFePO4 batteryView CEG batteries →

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How much battery you need

Evening use and CEG sizes.

Enter numbers without thousands separators: write 3000. Results use English formatting, for example 3,000 W and 3.5 kW.

What do you want to cover?

For full-day blackout backup, enter use over all 24 hours. Night-time use alone does not cover daytime demand.

Evening and night use

Enter the consumption for the selected period: one evening/night or a full 24-hour day.

Unit: kWh/night

Days of autonomy

Number of periods without recharging: nights in night mode, full days in 24-hour mode.

Unit: nights

Battery parameters — edit if known

Example starting values: 90% usable capacity and 95% battery-to-load efficiency. Replace them with the data for your system.

Usable capacity (%)

Percentage of nominal capacity you plan to discharge. This is not the initial state of charge.

Battery-to-load efficiency (%)

Includes losses between the battery and the loads. 100% excludes these losses; 95% is an editable example, not a certified value.

Assumptions: capacity = use per period × periods ÷ share of the battery you can use ÷ efficiency. Night mode covers nights only; 24-hour mode includes daytime use. Available CEG sizes: 16, 17 and 34.20 kWh; power and compatibility need a separate check.

I already have a battery: how long will it last?

Understand this estimate

Entered consumption is energy delivered to loads. The calculation divides it by share of the battery you can use and efficiency. Sizes are compared by capacity only: current, inverter power and BMS require separate checks.

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