What plug-in solar actually saves in Great Britain

The one number everybody quotes

The government's launch announcement put the figure at up to £110 a year, and most coverage has repeated it. That release names no household, no orientation, no kit size and no tariff, so there is nothing in it to check against. On this model it is wrong twice over: a large kit on a high-consumption household with an electric car cleared it comfortably, while a two-person flat facing west behind a neighbouring building did not come close. Both are ordinary British situations. The honest answer has a range in it and a reason attached, which is what the rest of this page is.

What actually decides it

Not the brand, and not — mostly — the balcony. Within a single household the slowest kit took between 2.4× and 3.2× as long to pay back as the fastest one. That is a bigger spread than the one between the best and worst locations we tested.

The mechanism is price per watt of panel. Two kits can carry the same 0.8 kW inverter and the same physics and differ threefold in what that panel capacity costs. Across the kits below the figure runs from £0.45 to £1.52 per panel watt, and they generate almost identically per watt; only one end of that range is cheap. That ratio is something you can check on any listing, including kits this site has never priced — divide the price by the panel wattage printed on the box.

Does the angle matter?

Two of the households below are deliberately the same house twice: same postcode, same consumption, same kits, mounted at 60° and 35° from horizontal. A steep bracket on a balcony rail sits near the first; a frame standing in a garden sits near the second. Comparing the two tables is the cleanest way to see what mounting angle is actually worth — and the answer is less than most people expect, well under what choosing a different kit is worth.

Six households, modelled

Each row states its own inputs. Find the one closest to your situation rather than reading the best case: annual consumption sets how much of the output you actually use, and orientation and shading set how much there is.

London flat, 1 person, south balcony

1,800 kWh a year · facing south · 90° from horizontal · light shading · postcode district SW1A

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 3.8 years. Slowest: 9.3 years — the same household, 2.4× longer, for buying a different box.

Manchester semi, 4 people, steep balcony bracket (60°)

4,200 kWh a year · facing south · 60° from horizontal · no shading · postcode district M1

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 2.3 years. Slowest: 6.9 years — the same household, 3× longer, for buying a different box.

Manchester semi, 4 people, garden ground mount (35°)

4,200 kWh a year · facing south · 35° from horizontal · no shading · postcode district M1

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 2.2 years. Slowest: 6.6 years — the same household, 3× longer, for buying a different box.

Bristol house, 3 people, EV charged at home

5,600 kWh a year, electric car charged at home · facing south · 60° from horizontal · no shading · postcode district BS1

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 2.0 years. Slowest: 5.8 years — the same household, 2.9× longer, for buying a different box.

Birmingham flat, 2 people, west-facing, shaded

2,900 kWh a year · facing west · 90° from horizontal · moderate shading · postcode district B1

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 4.5 years. Slowest: 14.3 years — the same household, 3.2× longer, for buying a different box.

Glasgow tenement, 2 people, east-facing

3,100 kWh a year · facing east · 90° from horizontal · light shading · postcode district G1

Fastest here: City Plumbing DMEGC 1030W Hoymiles HiFlow Plug In Solar Kit at 4.9 years. Slowest: 14.5 years — the same household, 3× longer, for buying a different box.

Why the same kit keeps winning, and why that is not a recommendation

One kit comes out fastest in every household above. That is a fact about our list, not about the British market. We hold sourced prices for 5 brands, because those are the ones whose sellers publish enough to identify what is in the box and tie it to an entry on the ENA register. Most manufacturers on that register have no findable retail listing at all.

So the row that wins here wins a race with 5 entrants. Read the mechanism rather than the name: it wins because it costs least per watt of panel, and any kit that beats it on that ratio would beat it here too. If you have found one we have not listed, that is the comparison worth making — not this one.

Being paid for what you export barely matters at this size

Across every row above, between 66% and 100% of what the kit generated was used in the house as it was produced. A device this small rarely outruns a household's own demand, so almost nothing is left to export. That matters because no supplier is obliged to pay you for exported electricity from a self-installed plug-in system — set out on our rules page with the quotes it comes from. It is a real gap in the scheme, and at this scale it costs you very little.

How this was worked out

• Sunlight — hourly output for each postcode district's coordinates from PVGIS (EU Science Hub, Joint Research Centre), radiation database PVGIS-SARAH3, weather year 2020, 14% system losses. A single weather year, not a typical meteorological year. Another year would move every figure here by a few percent.
• Demand — the hourly shape of British household electricity use from Smart Energy Research Lab — Aggregated statistics of energy use in GB domestic buildings 2022 and 2023, Statistical Dataset: Volume 2, scaled so each household's year totals its own stated consumption. Whether a home charges an electric car changes the SHAPE, which is why that is an input above; how much it uses in a year sets the level.
• Value — Ofgem energy price cap, 1 October–31 December 2026: 26.32p/kWh unit rate (Direct Debit average, England/Scotland/Wales). A daily standing charge of 54.83p applies but is not part of this figure — it is fixed, so it does not change the MARGINAL value of self-consumed generation, which is what a plug-in system saves. Checked 2026-09-01.
• The sum — for each of the 8,784 hours, the smaller of what the kit made and what the house wanted; that total times the unit rate; the kit's listed price divided by that. No export income, no subsidy, no price inflation, no panel degradation, and no allowance for a kit wearing out.
• Prices — read from the seller's own listing on the date shown on our cost page, which also records what each figure does and does not include.

What this is not

It is not a measurement and not a quote. Six modelled households cannot cover Britain, one weather year is not a typical one, and a 5-brand list is not the market. It is also not our product recommender: that applies eligibility rules and a ranking policy and is currently German-only, so nothing here is scored, ranked for quality, or recommended. The order of every table above is payback in this model and nothing else.

stromFit is paid nothing if you buy any of these. There is no affiliate arrangement behind any link on this page, and the ranking code carries no commission field for one to act on.

Sources

• PVGIS (EU Science Hub, Joint Research Centre) — hourly irradiance and temperature, PVGIS-SARAH3, 2020
• Smart Energy Research Lab — Aggregated statistics of energy use in GB domestic buildings 2022 and 2023, Statistical Dataset: Volume 2 — CC-BY (Attribution)
• Ofgem energy price cap, 1 October–31 December 2026: 26.32p/kWh unit rate (Direct Debit average, England/Scotland/Wales). A daily standing charge of 54.83p applies but is not part of this figure — it is fixed, so it does not change the MARGINAL value of self-consumed generation, which is what a plug-in system saves.
• Households can save as plug-in solar panels come to market — DESNZ press release, read on 2026-09-11 — the source of the single figure this page qualifies

Contains data from the Smart Energy Research Lab (SERL) Aggregated statistics of energy use in GB domestic buildings 2022 and 2023, Statistical Dataset Volume 2, University College London, licensed CC-BY.

Modelled on 14 September 2026. Prices and the register both move; this page is accurate as of that date rather than the date you are reading it.