Depending on the make and model of your battery and the way that you use it, its lifetime could vary slightly. While solar batteries are designed and optimized to undergo frequent charging and discharging, eventually, over many thousand cycles, the batteries will start to lose a small percentage of capacity.

Professionally installed home battery systems will always come with a warranty, which are usually around 10 years, and are guaranteed to maintain a certain level of performance e.g. the BYD B-Box has a warranty for 10 years for 80% of the original capacity; so, if your battery isn’t storing at least 80% of the energy it did when new within 10 years, BYD will replace it.

From our own experience of these products and the very slow degradation of the types of batteries used in the home battery systems, the likelihood is that a home battery system will usually significantly outlast the warranty.  It is the same as any other electronic product in this respect – if you bought a TV with a 5 year warranty, you would reasonably expect it to last for 10+ years.

The ability of the battery (and the solar system) to run independently of the grid depends both on the battery and the inverter. For example, Fronius and SolarEdge both offers inverters that, in combination with most battery types offer a safe backup system for your house in case of a black out.

Please ask our solar experts for the combination of inverter and battery that fits best for your needs.

If your household has very high energy requirements in the evenings, especially during longer winter nights, smaller battery storage systems may not be able to hold enough power for all of your needs all night. For example, if you wanted to run several ‘thirsty’ appliances at once in the evening, such as kettles, microwaves, washing machines, along with TVs, lights, fridges etc, your battery would discharge at a much quicker rate than that of a less busy household with lower energy demands. Home battery systems are also limited to the amount of electricity output they can give at any one time. It’s important to choose a battery storage system for your home which is best matched to your household’s needs. We can help you to find the best home battery solution for your individual circumstances – contact us today for more information.

We would typically size a system by following a two step approach:

- Economically, the ideal size for a battery is one that would cover your evening and night-time usage (with a little to spare, just in case). Your electricity demand will empty the battery by next morning, meaning it has the maximum possible space to capture the next day’s sunshine.
- We then sense check this against the size of your solar PV system. Obviously, there’s no point having a large battery if your generation is small – as you’d never be able to fill it.

So in practice, some home battery systems are sized to the demand of the home, but in some cases they are sized to what the solar PV system can produce.  Getting this right is complex, which is why our expert engineers are on hand to help you find the right system for your home.

It’s very difficult to say how much a home battery will save you, as it is highly dependent on both how much you personally use and how much you can generate.

Our analysis has shown that a battery can actually improve the payback of a solar PV system in some circumstances.  Where the solar PV system is large, the battery can be filled from solar PV for a greater proportion of the year, which improves the overall economics of the home generation system.

Overall, battery paybacks tend to sit in the 10-15 year range – this is above the warrantied lifetime, but within the lifetime that you might expect the product to last, as we have noted above.  We therefore consider battery storage systems as a broadly cost-neutral way for you to increase your own self sufficiency, and to be less reliant on more polluting grid electricity.