Are plug-in solar panels worth it in the UK?

The four numbers

Almost every disagreement about plug-in solar comes from people quoting one of these four numbers without the other three. The annual saving is:

annual generation (kWh) × self-consumption share × your unit rate (£/kWh) = annual saving

The payback is the delivered price divided by that annual saving. Panel brand, inverter efficiency and warranty length move the numbers only at the margin. The four numbers above set the answer.

Step one: generation

For central England, south-facing, at a sensible tilt, PVGIS gives roughly the following annual output. These are the best-case figures. A vertical balcony mounting or an east or west aspect will come in below them, sometimes well below.

800 W is the ceiling. SI 2026/848 caps a plug-in device at 800 VA or 800 W AC (the DESNZ Interim Product Specification expresses it as 800 VA apparent power measured as a ten-minute average, while the statutory instrument text says 800 watts), with 3.5 A AC and 2,000 W of PV DC input. You cannot buy your way past that within the plug-in framework, and under G98 Issue 2 Amendment 1 (2026) you may have only one device per household. The move to one device per circuit that was intended requires a G98 amendment that has not been made.

Step two: self-consumption, the multiplier that decides everything

This is where the money is won or lost. A plug-in device generates at midday. If nothing in your home is drawing power at midday, the electricity goes out to the grid and, as set out below, you are not paid for it.

• Out all day, no battery: roughly 30 to 35 per cent self-consumed.
• At home during the day, or with storage: roughly 70 to 90 per cent self-consumed.

That is close to a threefold difference in the value of the same hardware on the same wall. Before you look at any product, work out honestly which household you are. A fridge, a freezer, a router and standby loads give most homes a daytime base load of a couple of hundred watts, which an 800 W array will exceed comfortably on any bright day. Someone working from home, running a heat pump, charging a car in daylight, or simply doing laundry and cooking in the middle of the day is in a different economic position entirely.

Step three: your unit rate

Use your own rate from a recent bill rather than any national average. For the worked examples on this page we use about 25p per kWh, which is a reasonable round figure for a standard variable tariff. If you are on a time-of-use tariff with a cheap overnight rate and an expensive daytime rate, plug-in solar is worth more to you than these numbers suggest, because it displaces peak-priced units. If you are on a flat cheap rate, it is worth less.

On that basis an 800 W array saves roughly £50 to £60 a year if you are out all day, and roughly £150 to £190 a yearif you are at home during the day. The government’s own estimate for an 800 W system is £70 to £110 a year, which sits between the two and implies a middling self-consumption assumption.

Step four: the price, where the official figures and the market part company

The government’s impact assumption was a complete system at £400 to £600, central case £500. MoneySavingExpert’s four to six year payback follows from that assumption and a middling saving. The assumption is not unreasonable as a forecast of where a mature market might settle, but it does not describe what is on sale now.

The kits reaching the market at launch are priced well above the government’s assumption. No Amazon-listed kit has a confirmed entry on the ENA Connect Direct register yet, so ask the seller for the register reference for the exact model, and put the delivered price you are actually quoted into the arithmetic below.

The arithmetic

Putting the four numbers together, at about 25p per kWh, ignoring any export income and before allowing for degradation or inflation in electricity prices:

Savings rounded. Generation from PVGIS for central England, south-facing and tilted. A vertical or off-south mounting will be lower. Self-consumption taken as 30 to 35 per cent and 70 to 90 per cent. Unit rate 25p per kWh. No export income assumed.

Payback is the delivered price you pay divided by the figure in the relevant column. On the government’s £500 assumption for an 800 W system that is roughly eight to ten years if you are out all day and roughly three to four years if you are at home during the day. Every pound above that assumption lengthens it.

The uncomfortable case is a small array in a house that is empty from eight until six. A 460 W kit saving about £30 to £35 a year does not pay for itself inside its likely service life at the prices being asked at launch. A larger array is better value per watt, and better again if you are at home, but for a commuting household the payback at launch prices still runs well past a decade.

None of this means do not buy one. Electricity prices may rise, which shortens every figure here. You may value the device for reasons the arithmetic does not capture: portability, resilience, the simple fact of generating your own power. But you should go in knowing the number rather than the marketing.

Why export earns you nothing

The Smart Export Guarantee is the route by which small generators are paid for what they send back. It requires MCS certification of the installation and an export-recording smart meter. Plug-in solar sits outside MCS: there is no MCS standard for a device you plug into a socket yourself, and no installer to certify.

No government document states a legal exclusion, so this is properly described as a practical barrier rather than a ban. But the practical effect is the same. Assume every exported unit is worth zero, and size the array to what you can consume rather than to the 800 W limit for its own sake. If you are out all day, a smaller and cheaper device may actually give you a better return than a larger one, because you were never going to use the extra generation.

There is also no grant, subsidy or VAT scheme specific to plug-in solar that we have been able to identify.

What a battery changes, and what it costs you

A battery is the single most effective thing you can do to the arithmetic. It lifts self-consumption from about a third to about three-quarters, which roughly doubles the annual saving and moves an out-all-day household into something close to the at-home column.

“Add a battery to your plug-in kit” is the wrong way to think about it. If you are prepared to pay an electrician anyway, you are no longer shopping in the plug-in category, and you should compare a small conventional system with storage against a plug-in device on equal terms. For many households with a roof, that comparison does not favour plug-in.

Who this is genuinely good value for

• People at home during the day. Retired, working from home, shift workers, families with someone at home. Self-consumption in the seventies or eighties transforms the numbers.
• Households with a high daytime base load. A chest freezer, a home office, an air-source heat pump running in the afternoon, a car charged in daylight.
• Anyone with an unshaded south-facing position they can tilt. A garden, a flat terrace, a south wall. Tilt beats vertical by a wide margin.
• People staying put. Payback is measured in years, and while the device is portable, moving it means a fresh consent conversation and a fresh G98 notification.
• Flat dwellers with no roof option at all. If the alternative is nothing rather than a full roof array, the comparison changes. See our guide for flats and renters.

Who should probably wait

• Out all day, no storage, no intention of adding any. On current prices the payback is long enough that you should want a reason other than money.
• Moving within two or three years and not taking the device.
• North-facing or heavily shaded mounting positions. Partial shading costs proportionally more on a small array than on a roof.
• Leaseholders and renters without written consent. Get the permission before you buy the hardware, not after.
• Anyone who could fit a proper roof system. More generation per pound, and it qualifies for the Smart Export Guarantee.
• Bargain hunters. If price is the deciding factor, waiting to see whether the retailers named by GOV.UK actually enter the market is a rational choice, as long as you treat it as a gamble on prices rather than a certainty.

Two things not to get wrong when you buy

Compliance. A lawful device is battery-free, no more than 800 VA / 800 W AC and 3.5 A, with no more than 2,000 W of PV DC input, fitted with a non-rewireable moulded BS 1363 plug carrying a BS 1362 fuse of 5 A or less, and registered on the ENA Connect Direct database before it is placed on the market. Adaptors, convertors and extension leads are prohibited, so an EU kit with a Schuko lead cannot lawfully be adapted. See the Schuko problem. There is no BSI standard and no PAS. The controlling document is the DESNZ Interim Product Specification of 16 July 2026, based on DIN VDE V 0126-95:2025-12, and any claim of “BSI certification” is false.

Quality.The DESNZ electrical safety study by Arceio Limited with Eurofins E&E UK, published in June 2026, tested six systems. It concluded that plug-in PV can demonstrate safe and technically coherent behaviour, but also that product quality is not uniform across the market. That is a reason to buy from the register rather than from a marketplace listing.

And whichever device you buy, notify your distribution network operator no later than 28 days after commissioning using the Appendix 3 Form B under G98, and again on disconnection. The full framework is in our legal rules guide.

The verdict

Plug-in solar is worth it if you are at home in the daytime, have somewhere south-facing to put it, and intend to stay. On that profile an 890 W array saves something like £125 to £160 a year and keeps producing for years afterwards, which makes it a defensible use of the money at a sensible price.

If you are out of the house all day, have no storage and no plan for any, the same array saves about £55 to £65 a year, which is a very long payback at launch prices. You should either buy it for reasons other than payback or wait to see whether the market delivers the £500 system the government assumed. Neither answer is wrong. Work the arithmetic with your own figures before you take the seller’s.