Are solar panels worth it in the UK? Only if you use what you generate

Are solar panels worth it in the UK? Only if you use what you generate. That’s the honest answer, and it’s not the one most people are looking for when they ask.

Ask a homeowner why they’re hesitating on solar and they’ll usually tell you about payback time. Eight years, twelve years, whatever the quote says. It’s the number every salesman leads with, and it’s the wrong number to chase.

Here’s why. A decent array on a Sittingbourne roof generates plenty of power on a bright April afternoon. Trouble is, most houses are empty at 2pm on a Tuesday. Nobody’s home to use it. Export it back to the grid through the Smart Export Guarantee and you’re getting maybe 15p a unit, sometimes less depending who you’re with. Buy that same unit back at 7pm when the kettle’s on and the heating’s kicking in, and you’re paying three or four times that. The panels made free electricity all afternoon and you never touched it.

I fitted an 8-panel solar system in Ashford last spring for a couple who both work from home. Kettle, laptops, washing machine running through the day, self-use hit nearly 60%. Payback looked good on paper because the assumption matched their life. Down the road, a family with two people out at work all day put in almost the same system and their self-use came in under 25%. Same panels, same roof pitch, wildly different sums, because the number that actually decides whether solar pays isn’t the size of the array. It’s how much of what you make, you use.

A battery changes that arithmetic more than another panel ever will. Add one and you’re storing the 2pm surplus to run the house through the evening instead of selling it cheap and buying it back dear. I’ve seen self-use jump from a quarter to three-quarters once a battery went in, on the exact same roof, same weather, same panels. That’s the real lever. Not payback time on the panels alone, but whether you’re capturing your own power or handing it to the grid at a discount and paying it back at a premium.

None of which means everyone needs a battery from day one. If you’re mostly out during the day and can’t shift much of your usage, a well-sized array without one can still make sense at today’s prices, and you can always add storage later once the panels have paid for themselves. What I’d push back on is buying panels sized for a payback spreadsheet rather than your actual day. Ask an installer how much of your own generation you’ll realistically use before you ask how many years it takes to pay off, because that second number is built on an assumption about the first one that often doesn’t hold.

The other thing nobody mentions: an EV or a heat pump both love daytime solar, because they’re loads you can shift to whenever the sun’s out. Charge the car at lunchtime instead of overnight and the maths on the same panels looks completely different again. Solar isn’t one product with one payback time. It’s a set of decisions about when you use power, and the panels are only the first one.

So are solar panels worth it in the UK? For most Kent roofs I look at, yes, comfortably. But that’s not the same as saying every quote you get is worth signing. Get the sizing right for how you actually live, work out honestly whether a battery pays for itself given your pattern of use, and the panels almost look after themselves. Chase the payback number on the brochure instead, and you’ll end up disappointed by figures that were never really about you.