Sutton is one of the London boroughs signed up to the Mayor’s Solar Together group-buying scheme, and the council actively promotes registration. Across its phases the scheme has put panels on more than 3,000 London homes, so it is a real route — not a gimmick. What it is not is a guarantee that the group-buy price beats an installer’s quote for your particular roof. Here is how it works and how to judge it.
How a group-buy sets its price
Solar Together is a reverse auction. Households register their interest free, with no commitment. Installers then bid for the whole pool of registrants, and the lowest qualifying bid wins the round. Everyone who registered receives a personal offer based on that winning price, adjusted for their own roof and system size, and can accept or decline.
That mechanism does two useful things: it aggregates demand, and it forces a competitive bid. It also does something worth understanding: the winning installer has priced for the pool, not for you. If your roof is simple and south-facing you may be subsidising more awkward jobs; if it is complicated, the reverse.
What Sutton’s housing does to the comparison
Sutton’s stock is classic outer-London suburban. At Census 2021, 27.9% of households lived in semi-detached homes, 24.5% in terraced homes, 10.5% in detached houses and 31.3% in purpose-built flats. Owner-occupation is 64.4%.
That matters because a group-buy offer and an installer quote can only be compared on the same roof. A semi in Carshalton or Cheam usually carries the national-average array — the Energy Saving Trust puts a typical system at about 4.5 kWp, around twelve panels, costing about £7,600 installed (their figure, updated 27 August 2026). A terrace often takes fewer panels. A flat in one of Sutton’s purpose-built blocks is a leaseholder question before it is a price question, and no scheme changes that.
The honest comparison
Take the Solar Together offer and get a normal quote for exactly the same specification: the same number and wattage of panels, the same inverter make and rating, the same battery (or no battery), the same warranty terms, scaffolding included, grid notification handled. Then compare the totals. If the specifications differ, you are not comparing prices — you are comparing systems.
Two other things are true whichever route you choose. Residential installations carry 0% VAT until 31 March 2027, reverting to 5% after that. And export payments under the Smart Export Guarantee are set by each supplier and must be above zero — they change on short notice, which is why we never print a rate.
We are happy to be one of the two quotes. Our solar panels Sutton page publishes what a south-facing roof in the town is estimated to generate, using the European Commission’s PVGIS tool with the parameters shown, and our savings calculator lets you test your own usage against it before you talk to anyone.
The same borough scheme covers the villages east of the town centre: our solar panels Carshalton page sets the Village conservation area, the St Helier estate and the same UKPN connection against the group-buy question, and our solar panels Mitcham page does the same for CR4 across the borough line in Merton, where the scheme was not active when we checked.
One local proof point
BedZED — the UK’s first large-scale zero-carbon community — sits in Hackbridge in the London Borough of Sutton, about two miles from the town centre, with 777 m² of photovoltaic panels built into its roofs. Sutton Council declared a climate emergency on 22 July 2019 and pledged to make the whole borough carbon neutral by 2045, five years ahead of the national target. The borough is, in other words, unusually used to solar; a good installer here should be too.
Sources: GLA, Solar Together London; Sutton Council, Solar Together registration page; ONS Census 2021 (TS044, TS054); Energy Saving Trust, Solar panels: costs, savings and benefits explained (updated 27 August 2026); HMRC VAT Notice 708/6; Ofgem, Smart Export Guarantee.