Home battery storage systems are increasing in popularity in the UK, especially for those homeowners with solar PV systems also fitted. It helps them make the most of their solar energy generated and means that they can rely less on electricity from the National Grid when the sun isn’t out. We have answered some of the common questions asked about home battery storage systems here.
What is a home battery?
Why should I consider a home battery?
- Self-sufficiency. In general, we see that people want to be more self-sufficient and to run their homes off the electricity thy have produced themselves
- To run their car on sunshine. Even if you are out during the day, you can still use solar electricity to run your car. Store your generated electricity in a home battery, and then discharge this into your vehicle when you return home.
- To help the grid. Using a home battery reduces electricity demand at peak times (weekdays 16:30-19:30). That makes the UK’s overall system easier and cheaper to run. Peak demand also determined how many power stations we need – so if we can reduce demand at peak times we simply don’t need to have as many fossil fuelled power stations anymore
- Riding through power cuts. Some models of batteries allow you to use your stored electricity in the event of a power cut.
- Getting the cheapest electricity. A home battery can allow you to store cheap night-time electricity for use at other times. It means you always access the cheapest possible electricity, whether from solar or the grid.
How does a home battery work?
Do I lose my feed-in-tariff payments from my solar PV if I install a home battery system?
Do home batteries work with any type of solar panels?
An AC coupled battery system has a separate inverter in the battery itself. Solar DC electricity is converted to AC electricity for use in the home, and if it goes into the battery is converted to DC again. This is thermodynamically less efficient, but much more flexible. It allows batteries to be charged from any source, not just solar. They can be charged from the grid, for example when electricity is cheap, typically when there is a lot of wind power on the national grid. So it allows you to take advantage of cheap low carbon electricity no matter where it is generated.
It also means that the battery doesn’t need to be installed physically close to your solar PV inverter, which makes installation more flexible. For these reasons, the market is moving towards AC coupled systems as standard.
Regardless of whether you choose a DC or AC coupled battery storage system, it should be possible to install it with an existing solar PV system, when using an experienced approved installer like Joju Solar.
Can a home battery power my whole home at night?
What size home battery do I need?
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.
You will need to bear in mind that home storage batteries might well not receive enough energy to charge every day (depending on the weather and how much solar electricity your home generates and uses). Find out more about how this can work around the year here.
With a correctly-sized battery system for your home in the UK, you should ideally have enough energy waiting to meet your evening and overnight needs for the majority of the year, but are likely to need to draw electricity from the grid in the winter months.
How long do home solar batteries last?
The amount of time that the solar battery can run your home for will depend on the capacity of the battery system and the level of charge. Some home batteries, like the Tesla Powerwall 2, could potentially power your home for more than 24 hours from a full charge, because the capacity of the battery is more than the average daily household usage of electricity. However, if it is only partially charged, or if you have a battery system with less capacity, the energy won’t last as long when powering your home.
In terms of the life span of a home battery system, this can vary; depending on the make and model of your battery and the way that you use it. Whilst these types of batteries are designed and optimised 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 Tesla Powerwall 2 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, Tesla 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.
We can advise on the best home battery system for your needs and make sure that all warranty information is clearly understood, on all aspects of the installation. Get in touch today for more information.
Do home storage batteries come with warranties?
How much do home solar batteries cost?
The cost of a home battery system will depend not only on the brand of product, but also the size/capacity of the battery itself. Currently, the Tesla Powerwall 2 offers great value per kWh of storage, but if you are a smaller or less busy household then you may be better off with a smaller and cheaper system with less energy storage capacity.
Can any electrician install a home battery system?
We are fully signed up to the Renewable Energy Consumer Code, which enforces high consumer protection standards, following the consumer journey from start to finish, for businesses who are selling or leasing renewable energy generation systems to domestic consumers.
Get in touch with us for more information on installations.
Can home battery storage be installed outside?
How much can you save by having a home battery?
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.
We also know that where this is not possible, having the ability to top-up with cheap grid electricity when solar is not available, also massively improves the return on investment.
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.
Does a home battery work in a power cut?
Can I install a home storage battery if I don’t have solar panels?
Rather than the battery system being charged by solar energy, it can instead be charged with ‘cheap’ electricity from the grid (for those homes on a tariff that provides cheaper off-peak energy, usually overnight), which is then used in the home during peak times so that they don’t need to draw as much ‘peak-rate’ energy from the grid. This can mean savings on your electricity bills.
If you have any more questions about home battery storage systems or want advice on which might be the best choice for you, get in touch with us today!