Solar Panels With Battery: Are They Worth It in the UK?

The core comparison is solar alone versus solar plus battery. Solar on its own can cut imported electricity during the day and may also earn export income for unused generation. A battery changes the equation by storing more of that surplus power for later use in the evening or overnight.

That matters because electricity you use yourself is usually worth more than electricity you export. Ofgem's Smart Export Guarantee requires eligible suppliers to pay for exported power, but suppliers set their own rates and those export rates are often well below the full retail electricity price. Energy Saving Trust also highlights that batteries mainly improve value by increasing self-use of solar electricity rather than by changing how much the roof generates.

There is also a second question that matters for some households: is a battery worthwhile even without solar? For homes on EV-style tariffs or other very cheap off-peak rates, the answer can sometimes be yes. If night-time electricity costs a fraction of daytime electricity, a battery may be able to buy low overnight and reduce expensive daytime imports even without rooftop generation.

A typical domestic solar PV system of around 3.5kWp costs about £6,100 to install, according to Energy Saving Trust. For battery storage, Energy Saving Trust says a 5kWh battery system costs around £4,600, although actual prices vary by size, brand, inverter arrangement, and whether it is installed at the same time as solar.

That means a solar-plus-battery decision is not just a small upgrade on top of solar. In broad terms, adding a battery can increase total upfront cost by something close to three-quarters of the cost of the solar system itself. That is why the extra savings have to be meaningful enough to justify the extra capital.

If you are considering battery-only economics, the battery still needs to justify itself against tariff arbitrage alone. In that case, the important comparison is the capital cost of the battery versus the value of shifting cheaper overnight electricity into more expensive daytime periods.

Solar only tends to save money mainly through daytime savings. If you are home during the day, run appliances while the sun is up, or can shift washing, dishwashing, and hot water loads into daylight hours, solar alone can already be strong value.

Solar plus battery adds another layer of savings by improving self-use. Instead of exporting more surplus power in the afternoon and buying back electricity later at a higher retail rate, the battery can hold some of that surplus and release it later when the home needs it. Energy Saving Trust describes this as one of the main reasons batteries can improve the economics of a solar setup.

For some tariff structures, batteries can also create savings without solar by charging overnight and discharging during the day. That is especially relevant where EV tariffs offer very low overnight rates and much higher daytime import prices. In those cases, the battery's value comes from time-shifting cheaper grid electricity rather than only from storing solar generation.

Batteries tend to make most sense where a household has high evening usage, because that is when stored solar energy can offset otherwise expensive imports. Homes with a lot of electricity demand after sunset often get more useful cycling out of a battery than homes whose loads are mostly daytime.

They can also be attractive where EV charging or wider electrification is part of the picture. Energy Saving Trust notes that batteries and time-of-use tariffs can work particularly well together, and that solar can also support EV charging and electric heating. If the home has high electricity prices, or a meaningful gap between standard import prices and export value, the case for self-use becomes stronger again.

This is where cheap overnight EV-style tariffs become especially interesting. If the home can charge a battery overnight at a very low rate and discharge it during expensive periods, the battery may deliver meaningful value even before solar is added.

Batteries are not always the right answer. If a household has low electricity usage, uses a lot of power during the day anyway, or already gets limited extra benefit from stored energy, the incremental value of a battery can be modest.

They can also be less compelling if the total payback becomes too long. Energy Saving Trust notes that batteries are a good option for many homes, but also points out that the upfront cost can make them unrealistic for some households and that battery lifespan is shorter than solar panel lifespan. In other words, a battery can absolutely improve a solar system, but it does not automatically make every solar project better value.

Battery-only setups can also disappoint if the tariff spread is not large enough, if daytime consumption is too low, or if the battery spends much of its life underused. Cheap overnight electricity helps, but it does not guarantee strong economics on its own.