Battery Storage 101: When Adding a Solar Battery Makes Sense

Battery storage has become one of the most discussed additions to solar systems in recent years, and for good reason. As export rates remain modest and import prices stay high, the case for storing your own generation and using it later is increasingly strong.

But a battery is not always the right choice for every property or every situation. Here is a straightforward guide to when it makes sense, and when it might not.

What Does a Solar Battery Actually Do?

A solar battery stores the electricity your panels generate that you do not immediately use. Rather than exporting that surplus to the grid at a relatively low rate, you hold it in reserve and draw from it later — typically in the evening, when your panels are no longer generating but your consumption continues.

Done well, this reduces your grid imports significantly and increases the proportion of your electricity that comes from your own system rather than your supplier.

When a Battery Makes the Most Sense

Your household or business is not home during the day. If your property is empty during peak generation hours, you are currently exporting most of your solar output and importing from the grid in the evening. A battery corrects this mismatch almost entirely.

Your import rate is significantly higher than your export rate. This is the case for most UK consumers. Every unit you store and use yourself saves you the full import rate rather than earning you the lower export rate. The margin between the two is your effective saving per kilowatt hour stored.

You want greater energy independence. Beyond the financial case, many of our clients value the resilience that battery storage provides. Some systems can operate in islanding mode during a grid outage, keeping essential loads running when the wider grid is down.

You want to take advantage of time of use tariffs. Several energy suppliers now offer tariffs with significantly cheaper overnight rates — sometimes as low as 7 pence per kilowatt hour versus daytime rates several times higher. A battery can charge overnight on cheap grid electricity and discharge during expensive peak periods, independently of your solar generation.

You are a commercial customer with demand charges. As discussed in our earlier article on demand charges, a battery can be programmed to discharge precisely at moments of peak demand — reducing the grid draw that triggers your highest charges.

When a Battery May Not Be the Priority

If you are home during the day and your self consumption of solar is already high, a battery may add cost without proportionate benefit. Similarly, if your system is small relative to your consumption, there may not be much surplus to store in the first place.

In these cases, the better first step is often to optimise how you use your existing generation — shifting loads to daylight hours before committing to storage.

What Size Battery Do You Need?

Battery capacity is measured in kilowatt hours. Most UK residential installations use between 5 and 15 kilowatt hours of storage, with 10 kilowatt hours being a common starting point for a family home.

The right size depends on your evening consumption profile, how much surplus your panels generate on a typical day, and whether you want to cover just the evening or also provide resilience through the night.

Freedom Energy sizes battery systems based on real consumption data, not rules of thumb. We model your specific profile to ensure the battery you install is the one that delivers the best return for your circumstances.