What a watt of plug-in solar actually costs in Britain

Plug-in solar is sold in pounds and used in watts, and almost every piece of coverage since the law changed has quoted the first and ignored the second. That is how a £449 kit gets called the cheapest way into solar when it is one of the worst-value products on the approved list, and how a £989 kit gets called expensive when it is among the best. Price per watt is the only comparison that survives the difference between a single 400W panel and a 1260W pair, and nobody in the UK was publishing it, so we are.

This page is the index and the method behind it. The underlying data is the same file that drives every price on this site, and it is downloadable as a CSV under a Creative Commons attribution licence. Take it, check it, argue with it.

The index since it started

Two readings is a start, not a trend, and I would rather say that now than have it pointed out later. What the second reading does show is direction: the median fell 8.6% and the best available rate fell 12.3% in eight days, and both moves came from one new entrant reaching the market rather than from any incumbent cutting a price. Nobody on the list has dropped a price yet. The falls are entirely composition.

Every priced kit, ranked by what a watt costs

Sorted cheapest per watt first. No affiliate links anywhere on this page, and Plug Solar Hub earns nothing from any seller of a compliant kit.

Three things the index shows that a price list does not

Size buys itself, and it is not close. The 1260W UKSOL Pro Max is £0.78 a watt and the 460W UKSOL Pro Compact is £1.85, the same manufacturer, the same inverter class, a difference of 137%. The fixed costs of a plug-in kit, the inverter, the plug, the cable, the type testing, the delivery, do not shrink when the panel does. If you have the wall or the ground for two panels, buying one is the most expensive decision available to you.

The mount is a bigger line item than anyone admits. The identical UKSOL 890W kit is £0.95 a watt on a hybrid mount and £1.07 on a ground mount, and that is at the cheapest seller for each. At Argos and UKSOL direct the ground mount version is £1.35. Before you compare two kits, check you are comparing the same mounting, because the frame can move the per-watt figure further than the panels do.

The cheapest entry ticket and the best value are never the same product. The cheapest kit outright is £449 for a PatioSun Lite at £1.12 a watt. The best value is a PatioSun Max at £599 and £0.69. An extra £150 buys 470 more watts of panel, which is more than double the generation for a third more money. That trade holds across the whole table, at every manufacturer, which is why the index is a more useful headline than the floor price.

How the index is calculated

The rules are deliberately dull, and published so anyone can reproduce the number.

• The basket is every kit showing Compliant on the ENA G98 Type Test Register that has a retail price on a seller's own page. Approved kits nobody sells are excluded, and there are currently thirty of them.
• The price is the lowest we can find, inclusive of VAT and delivery, read on the seller's page rather than taken from a press release or a comparison site. Where a seller's checkout differs from its listing, the checkout total is used.
• The denominator is total panel wattage, not inverter rating. Every compliant kit is capped at 800 VA of export, so inverter rating would make every kit identical and tell you nothing.
• The statistic is the median, not the mean. The range runs from £0.69 to £1.85 and a single ground-mount outlier would drag an average around.
• One price per kit, so a model sold in five places counts once, at its cheapest.
• Readings are taken when the register moves, not on a fixed calendar day, and every reading is dated and kept.

What the index cannot tell you

Four limits, and they matter more than the number while the series is this young.

• The basket is not held constant. This is a median of what is on sale on the day, not a fixed basket tracked over time, so a fall can mean prices dropped or simply that a cheaper maker arrived. In this reading it is entirely the second.
• It is weighted towards UKSOL, because UKSOL is six of the eleven priced kits. That is a fair description of what a buyer meets in the shops today, and it is not a manufacturer-neutral average.
• It says nothing about quality, warranty or whether the thing arrives. Lead times are tracked separately on where to buy. One of the cheapest entries is a pre-sale from a seller whose checkout charged £100 over its listed price on another product. Per watt is a price measure, not a recommendation.
• It excludes the thirty approved kits with no public price, and if those land cheaply the index will fall sharply, which would tell you about supply rather than about anyone cutting margins.

Using or quoting this index

The index is free to use, including commercially, with attribution to Plug Solar Hub and a link to this page. If you are a journalist, an analyst or a manufacturer and you want the underlying rows, the CSV carries every price with its seller and the date it was read. If you think a figure is wrong, tell me and I will check it against the seller and correct it with a dated note, which is what happened to the PatioSun Duo on this very page: it was published at £549 and a reader found the checkout charging £649.

I have no commercial relationship with any manufacturer or seller of a compliant kit, there are no affiliate links on this page or on the register tracker, and the only thing I want from you is that you check the model code against the register before you plug anything in.

Sources: ENA G98/G99 Type Test Verification Register, Plug-in Solar device type, register read 4 September 2026; individual seller pages on the dates shown in the table. DESNZ Plug-in Solar Device Interim Product Specification v2.0, 16 July 2026, for the 800 VA cap. Educational information, not financial or electrical advice.