A homeowner in the United Kingdom considering a £1,800 (~$2,415) battery upgrade discovered a frustrating obstacle. The additional storage would need at least 1,000 fully utilized days to recover its cost, with sunny days potentially stretching that timeline over many years.

Here's what to know

Electricity sent to the grid earns this homeowner 13 pence (~17 cents) per kilowatt-hour, while overnight battery charging costs 6.6 pence (~9 cents) per kilowatt-hour, they wrote on Reddit's r/SolarUK community. They described their solar-panel setup, which includes a 6-kilowatt-hour battery, and their dilemma.

Evening electricity costs 34.5 pence (~46 cents) per kilowatt-hour when the homeowner must buy it from the grid. That becomes necessary on cloudy days when the battery runs out around 5 p.m.

The owner put the break-even point at roughly 6,000 kWh of avoided peak-rate purchases for an upgrade adding 6 kWh of storage. The quoted price includes installation.

For homeowners comparing options, exploring EnergySage can help them learn about home battery storage, including competitive installation estimates.

EnergySage has teamed up with electrification brand Qmerit to help homeowners get the best price on home battery storage solutions. Comparing installation costs matters, as this owner's calculation shows, because upfront prices heavily influence payback.

More background

For the investment to pay off, there would need to be enough days when the homeowner actually needed the additional storage, rather than days when sunshine could cover their electricity needs.

"Without this, it's 1000 days where I don't generate at least 6kWh, so realistically a lot longer than three years (in the last year I generated less than this on 110 days)," the original poster explained in a reply.

Another commenter said automated scheduling, rather than a manual schedule, was needed to keep up with changing prices in their setup. They reported earning 20-30 pence per kilowatt-hour for electricity exported during afternoon peak periods.

Adding battery storage can protect your home during outages when paired with compatible backup equipment, such as the gateway discussed in the thread. It can also lower energy costs and provide more energy independence, although savings depend on sizing and usage.

What can be done?

A commenter facing a similar decision planned to make a determination by reviewing their past electricity usage.

Between 11:30 p.m. and 5:30 a.m., one Scotland-based commenter shared they run their washing machine, dishwasher, and tumble dryer during off-peak hours. They also charge their 15 kWh battery overnight at 6 pence per kilowatt-hour, having chosen that capacity to meet their needs during dark winters.

For the original poster, shifting appliance use could reduce evening electricity purchases without the expense of another battery. A commenter recommended trying that approach before adding storage.

One more factor was the rates.

"You're doing numbers with current prices," a user wrote. "I was doing the same last year, then I doubled my battery in February. No regrets as numbers for this winter are different!"

Each increase in storage capacity does not necessarily deliver the same savings, as one commenter pointed out.

"The first kWh is the most valuable the last is the least," they wrote.

For those prioritizing backup, Pila is another company offering strong battery backup options. Pila's plug-and-play batteries cost a fraction of a whole-home backup system.

Where can I learn more?

Other UK homeowners are also working out whether extra battery storage is worth the cost, with battery size and electricity tariffs shaping their decisions. 

• A UK homeowner weighing two larger battery sizes calls the upgrade a comfort purchase.

• A UK homeowner considering battery-only home storage gets a warning about G98/G99 requirements.

• A UK owner finds overnight battery charging worthwhile when export rates exceed charging costs.

• A UK homeowner revisits retrofitting home battery storage after an installer dismissed its value.

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