How do I calculate the payback time of a home battery?
The simplest sum: the purchase price divided by what the battery saves per year. If the result is longer than the battery's lifetime, it does not pay for itself. The tricky part is the saving per year.
The saving depends on your own consumption and generation per hour: how much solar power you have left over during the day, how much you use in the evening and at night, and which contract you have. So calculate with your own hourly consumption, not with averages. An average day does not exist: in summer the battery fills up, in winter it often stays empty, like a rain barrel.
What else counts
A battery deteriorates somewhat over the years and can then store less. Electricity prices change, and with them what a stored kWh is worth. And money you put into a battery cannot be saved or used to pay off debt. The more weight you give these points, the longer the payback time becomes.
Price with or without VAT
With a dynamic contract and smart control you can often reclaim the VAT on the purchase of a fixed battery. Then you calculate with the price excluding VAT; otherwise with the price including VAT.
How the calculator does it
The calculator works out the saving for every hour of a year, including losses and standby, and divides the purchase price by it. Without a price it uses a range of common prices; you can also enter the price from your quote. What does and does not count is on How does this calculator work?
Calculate the payback time of a battery
An estimate, not personal advice. How the calculator works: How does this calculator work?
Other questions
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