A bigger inverter doesn’t fill the batteries

Solarwyse · 3 min read

Think about a vehicle

A bigger motor doesn’t give a vehicle a bigger fuel tank. An inverter and a battery bank have a similar relationship: one supplies power, while the other stores energy.

Power is what is happening now

Power is measured in watts or kilowatts. The inverter must handle the loads you want to run together, including short starting demands. The batteries must also be able to supply that power.

Energy includes time

Energy is measured in watt-hours or kilowatt-hours. A 100-watt load running for 10 hours uses 1,000 watt-hours, or 1 kilowatt-hour, before system losses. The same load running for one hour uses a tenth as much energy.

That is why a small load left on all day can matter as much as a larger appliance used briefly. We consider both the size of each load and how long it operates.

The batteries still need recharging

Adding battery capacity can give you more stored energy, but it doesn’t create energy. The solar array and backup charging still need to replace what the household uses, allowing for losses and seasonal conditions.

A useful design matches inverter output, usable storage and charging. We’ll explain the limits of each part so you know what to expect.