Is adding a battery to solar PV worth it?

1. The gap between feed-in and purchase

Battery economics rest on one difference: how much you get for a kilowatt-hour sent to the grid and how much you pay for a kilowatt-hour drawn from the grid in the evening. Every kilowatt-hour the battery shifts from midday to evening saves you exactly this difference. The lower the feed-in price and the higher the purchase price, the faster the battery pays for itself.

Take your last bill and your feed-in contract. Both numbers are there.

2. How much electricity you send to the grid

A battery can only store what would otherwise flow out. Check in the inverter app or the grid operator portal how many kWh a year flow out. If it is little, for example with a smaller PV and high daytime consumption, the battery will have nothing to fill up from.

3. When you use electricity

A household that is away during the day and cooks, washes and turns on the lights in the evening gets more out of a battery than one that uses most electricity during the day. Hourly consumption data shows it precisely. You can download it from your grid operator portal.

4. What your inverter allows

A hybrid inverter connects a battery directly and at lower cost. A grid inverter needs a separate battery system on the AC side, which costs more but works. You will find the inverter type on its label. More in A battery for the solar system you already have.

Putting it together

From the four inputs above you can calculate how many kWh a year the battery really shifts and how much that saves. Against this stands the battery price and its lifetime: manufacturers rate LFP batteries for thousands of cycles and usually give a 10-year warranty. When the annual saving multiplied by the years of life exceeds the price with a margin, the battery makes sense.

We do the calculation for your house free of charge from your data. Just send your consumption and a photo of the inverter label.

• Battery for solar
• Choosing capacity
• Home storage