Already Have Solar Panels? Here’s Why a Battery Could Be Your Best Upgrade
If you already have solar panels, you’ve done the hard part. But there’s a good chance you’re giving a lot of your free electricity away.
Without storage, most of the power your panels make during the day goes straight back to the grid, often for a fraction of what you then pay to buy electricity back in the evening. With the price cap up again this month, that gap is bigger than ever. Adding a battery is one of the most effective upgrades you can make, and you don’t need to replace your panels to do it.
The problem with solar on its own
Your panels generate most around the middle of the day. But most households use the most electricity in the morning and evening, when people are home, cooking, washing and watching TV.
That mismatch means a typical home without a battery only uses somewhere around a third to a half of its own solar power. The rest is exported.
Exporting isn’t worthless. Under the Smart Export Guarantee you get paid for it. But the rate you’re paid for exporting is usually well below the 26.32p per kWh price cap rate you pay to import electricity from October. Every unit you export at midday and buy back at 7pm is money left on the table.
What a battery does for you
A battery soaks up the spare solar power your home isn’t using during the day and gives it back in the evening. Instead of exporting cheap and importing expensive, you use your own electricity when you actually need it. Many homes can push their solar self use up to around 70% or more with a well sized battery.
It earns its keep in winter too. When the panels are generating less, your battery can charge overnight on a cheap off peak tariff from a smart meter and power your home through the expensive daytime and evening hours. That means it’s saving you money all year round, not just in summer.
Other benefits worth knowing about:
- Less exposure to price rises. The less you buy at peak rates, the less the next price cap change affects you.
- Smarter control. Modern batteries come with apps that show what you’re generating, storing and using in real time.
- Backup options. Some systems can keep essential circuits running during a power cut, depending on the setup.
On the old Feed-in Tariff? Good news
If your panels went in before April 2019, you may still be getting Feed-in Tariff payments. Lots of FiT customers worry that adding a battery will put those at risk. In most cases it won’t.
Ofgem has confirmed that homes on “deemed” export, where you’re paid for 50% of what you generate whether you export it or not, can keep those payments after adding a battery, as long as the usual eligibility rules are still met. That makes a battery especially good value: you keep being paid for deemed export, and every unit you store instead of sending to the grid is a unit you don’t have to buy.
The key is installing it correctly. The battery needs to be wired so your generation meter still only records what your solar panels produce, and you should let your FiT provider know about the change. We’ll take care of the setup and point you to exactly what to tell them.
Is my system suitable?
Almost any solar system can have a battery added. The question is how. There are two main approaches:
- AC coupled. The battery comes with its own inverter and sits alongside your existing setup. This is usually the simplest option for retrofits, because it doesn’t touch your current solar inverter.
- Hybrid inverter. Your old solar inverter is swapped for a hybrid one that runs both the panels and the battery. This can make sense if your existing inverter is getting old, since inverters typically need replacing at some point during a system’s life anyway.
When we survey your home, we’ll also look at how much electricity you use and when, how big your solar array is, where the battery can go, and whether a smart meter and time of use tariff would help. That way the battery is sized to your home, not oversold.
The batteries we fit, and why now
We install batteries from Hanchu, Fox ESS, Sigenergy and Tesla Powerwall, and we’ll recommend the one that fits your existing system, your usage and your budget.
There’s also a deadline worth knowing about. Since February 2024, adding a battery to existing solar panels has qualified for 0% VAT when it’s supplied and installed together. That relief ends on 31 March 2027, after which it goes up to 5%. Getting your battery in this winter means you avoid that extra cost and start saving straight away, through the coldest, most expensive months of the year.
Get more from the panels you already have. Get a no obligation battery quote from Spectra Solar and we’ll show you how much more of your own power you could be using.