MoneyWeek article: Are plugin solar panels worth it

“Plug-in solar could make home-generated electricity accessible to many more households, but savings of hundreds of pounds should be treated as a possibility, not a promise.

“Whether it is worthwhile depends on the purchase price, orientation, shading and how much electricity the household uses while the panels are generating. If they are bought using credit, the interest must also be included in the payback calculation.

“Buyers should check that the product meets the new safety requirements, their electrical setup is suitable and they have any necessary landlord or freeholder permission. The right setup could reduce bills, but poor placement or expensive finance could quickly wipe out the benefit.”

I like the idea, but let’s not sell a £400 solar kit as a magic answer to energy bills.

For the right household, plug-in solar could be brilliant: low upfront cost, no huge rooftop installation and, importantly, access to solar for renters and people in flats who have largely been locked out until now.

But the savings need perspective. Government estimates are around £110 a year, not hundreds for everyone, and you save most when you actually use the electricity while it is being generated. A badly positioned panel or an empty home during the day changes the maths quickly.

Consumers also need to check electrical safety, landlord or freeholder permission and where the panels can legally be installed.

I think the real innovation is accessibility. Solar is becoming something you can buy, plug in and understand not a £7,000 home-improvement project.

They're worth it for a household that's home during the day, and oversold for everyone else. A government-commissioned independent study found no evidence that a properly designed unit is unsafe in itself when used as intended. The best case in the government's own impact assessment is a saving of about £110 a year. That assumes a south-facing panel, tilted just right, with most of the power used in the house the moment it is made. Hundreds of pounds a year is not what the modelling shows. Then there's the part that rarely gets priced in. Buy a kit off the shelf and fit it yourself and you pay VAT at 20 per cent, because the zero rate for energy saving materials only covers the goods when the seller fits them as well. And no supplier has to pay you for the surplus you send back to the grid. So before you buy, work out how much electricity your house really uses in the middle of the day. If the answer is not much, neither is the saving.