How long does a solar battery last?

There are two questions hiding in that one: how long a charge lasts you in the evening, and how many years the battery itself will last. The first depends entirely on how much power your home uses, the second on the battery's warranty and how it is looked after. Neither has an honest one-number answer, so be wary of anyone who gives you one.

On a daily basis, a battery covers your home once the sun has gone, the evening, the overnight, the early morning, until the panels take over again. How far it stretches comes down to your demand, not a headline figure on the spec sheet. A home running the oven, the dishwasher and the tumble dryer in the same evening will draw a charge down far faster than a quiet household, even with the identical battery. That is why a battery should be sized to how you actually use power, not to whatever number looks impressive in the quote.

This is also why "how big a battery do I need" is the better question. Fit one that is too small and you run out before bedtime and start buying expensive evening electricity again; fit one that is too large and you have paid for capacity you never empty. We look at when and how much you use, and size the battery so it does real work most days rather than sitting half full or running flat.

On lifespan, modern home batteries are designed to be cycled, charged and discharged, every day for many years. They lose a little capacity gradually over their life rather than failing suddenly, much like a phone battery but engineered to degrade far more slowly. The meaningful number is the manufacturer's warranty, which typically guarantees the battery will still hold a stated share of its original capacity after a set period or number of cycles.

We fit batteries from established manufacturers such as GoodWe and Fox ESS, and we go through the actual warranty terms with you before you commit, what is covered, for how long, and what capacity it guarantees at the end, so you are judging it on the real paperwork rather than a salesperson's round number. If a battery does not stack up for your usage at all, we will say so instead of selling you one.

More on this: battery storage in Leicester.

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