A Brief Guide to
Domestic Battery Storage
1. What is Domestic Battery Storage?
Domestic battery storage is a continuously evolving technology that is typically used alongside solar PV systems. Batteries enable you to store excess electricity rather than export it to the National Grid. Because it costs more to import electricity than you get for exporting it, this helps to reduce your electricity bill.
Improvements in battery technology and increased competition in the market has led to a reduction in cost, making battery systems more viable in a domestic setting, with numerous companies providing battery storage options.
Normally, any excess electricity generated by your solar PV panels is exported to the grid, and the amount you are paid to export this electricity is typically around 4p per kWh. To import the same amount of electricity will cost you around 15p per kWh. So storing this excess electricity in a battery for use later could save you around 10p per kWh.
The benefit of battery storage here is that any excess electricity generated during the day can be stored and used at night, or at times of peak demand. If your household is on a multi rate tariff, then cheaper rate electricity can be used to charge the batteries at night and off-set more expensive day time rates.
Some electricity suppliers have packages in place where they will pay you for access to your battery storage, to help support the growth of renewable energy on the grid.
Battery storage means you can utilise up to 100% of the electricity generated from your solar PV. Reducing your reliance on the National Grid will help to make significant carbon savings. Some batteries can export and import electricity directly into the grid, helping to balance the demand on the grid at peak times. This also helps to reduce carbon emissions at these times.
3. Property Suitability
A suitable area will be required for the batteries, such as a garage or an enclosed outdoor space. If they are installed outside then they should be kept well away from any downspouts or other water sources. If the batteries are installed inside then they should be in a secure area where they will not be damaged.
4. Typical Costs
The cost of your system will depend mostly on the size of battery required and the manufacturer. According to the Energy Savings Trust, a 4kWh system would cost in the region of £4,000 to £6,000. However, this cost is expected to reduce in the future as the technology is improved.
Installing a battery storage system is a relatively simple process and will typically only take a day or two to complete. They can be fitted at the same time as a solar PV system, or retrofitted at a later date.
We recommend you check that your chosen installer is signed up to the Renewable Energy Consumer Code (RECC). This means they are committed to a high standard of conduct and will provide detailed information about your installation. The Microgeneration Certification Scheme (MCS) is in the process of developing certification for battery storage systems, which will ensure consumer protection. This is not yet live however.
Domestic batteries required very little maintenance and most manufacturers provide a 10 year warranty with their systems. Batteries have an expected lifespan being between 10 and 15 years, beyond which the actual storage capacity of the battery will begin to decline. This is a shorter expected lifespan in comparison to a solar PV array. Therefore, if you are using the batteries in conjunction with a PV array then the batteries will need to be replaced during the lifespan of the PV array.
If the battery system is installed outside, it must be kept clear of leaves or build-up of other objects, in order to maintain proper ventilation.
Extreme temperatures can have an adverse effect on the lifespan of the battery. However, as the UK is not subject to extreme temperatures very often this should not be a problem.