Solar Battery Calculator

Estimate solar battery capacity, usable kWh, battery count, backup runtime, charging time, inverter load, depth of discharge, battery cost, and backup coverage. This calculator is useful for solar storage, home backup, RV systems, cabins, and off-grid planning.

Calculate Solar Battery Size

Usable battery kWh = battery kWh × battery count × depth of discharge × inverter efficiency.
Your result will appear here.

How the solar battery calculator works

Battery capacity:
The calculator multiplies battery kWh by battery count, then applies depth of discharge and inverter efficiency.

Backup runtime:
Usable kWh is divided by the backup load to estimate how many hours the battery can run.

Charging time:
Solar charging is estimated from solar array kW, peak sun hours, and charge efficiency.

Why use a solar battery calculator?

A solar battery calculator helps estimate how much battery storage is needed for backup power, solar self-consumption, RV power, cabins, or off-grid systems.

It can help with home backup loads, fridge backup, lighting, outlets, internet equipment, sump pumps, RV systems, cabins, and solar charging plans.

What your result means

Your result shows total battery capacity, usable battery capacity, backup runtime, required battery size, batteries needed, solar charge time, load coverage, amp-hours, total cost, estimated value per cycle, and detailed backup load totals.

Solar battery calculator formulas

Frequently asked questions

How do I calculate solar battery size?

Multiply the load in kW by the backup hours needed, then adjust for depth of discharge, inverter efficiency, and reserve capacity.

What is usable battery capacity?

Usable battery capacity is the energy available after accounting for depth of discharge and inverter losses. It is usually less than the nameplate battery capacity.

How long will a solar battery run my house?

Divide usable battery kWh by your average load in kW. A 10 kWh usable battery can run a 1 kW load for about 10 hours.

Can this calculator design my final battery system?

No. This calculator gives a planning estimate. Final battery systems should account for inverter limits, surge loads, code requirements, battery chemistry, temperature, ventilation, disconnects, overcurrent protection, manufacturer instructions, and local inspection rules.