Tool · Economics

Does it pay off?

It is the question everyone starts with, and the one quote portals always answer yes to.

Where you are

Between Europe's dearest and cheapest kWh there is a factor of four, and export rules change every year. Without the country this calculation cannot be made.

Your country

Choose your country on the map, or from the list.

The darker countries are the 6 we have verified parameters for. For the others we invent nothing: we ask what you pay per kWh, and the calculation states that the number is yours.

The electricity price comes from Eurostat, for every country from the same consumption band — the typical household — so that the countries really are comparable. The export payment does not: that changes from supplier to supplier, and where we do not know it we ask you.

The system you are considering

What it costs, all in € Battery, inverter and installation: what actually leaves your account. Usable capacity kWh Not the nominal figure: the one that actually comes out. Many manufacturers do not state it — on the sheet we say so. Standby consumption W What the system uses simply to exist. Twenty watts is 175 kWh a year — often more than the battery saves in a month. It is the line missing from every commercial calculator, and the one that turns the result around.

How you use it

We fill these three in if you do not change them, and they are assumptions, not data: changing them changes the result, and that ought to be visible.

Cycles per year cycles 365 means one charge and one discharge a day. Under panels in winter it is far fewer. Round-trip efficiency % How much is lost on each pass. None of the sheets in the catalogue state it: 90% is a cautious estimate. Working life years Beyond that, a payback is not a payback. Look at the battery life cycles on the sheet: the warranty often ends sooner.

Do you also have a dynamic tariff or a subscription?

Gain from dynamic tariffs € a year Buying when it is cheap and using it when it is dear. It has to be stated, not inferred: studies put it at a few tens of euros a year for small storage. Subscription or maintenance € a year

Where you are

The system you are considering

How you use it

Further reading