A 10 kW solar system: cost and output
Ten kilowatts is the top of the 4–10 kW published cost band and the practical ceiling for a domestic single-phase supply. Whether it is possible at all depends on your supply and your network operator, not on your roof.
| Roughly how many panels | 24 at 430 W |
|---|---|
| Published size band | 4-10 kW |
| Installed cost, median | £15,459 (£1,546/kW) |
| Installed cost, mean | £16,218 (£1,622/kW) |
| Generation, south-facing at 35° | 8,560 kWh a year for a median location; 6,920 to 10,420 kWh across our 25 reference locations |
Cost: Solar photovoltaic (PV) cost data, Department for Energy Security and Net Zero, 2025/26, Total Installed Capacity basis, OGL v3.0. Generation: our own PVGIS modelling at 20% system losses — see generation by region. Panel count is illustrative and depends on the modules quoted.
| Self-consumption | Used at home | Exported | At 12.0p export | At 4.1p export |
|---|---|---|---|---|
| 14% | 1,198 kWh | 7,362 kWh | £1,196 | £615 |
| 19% | 1,626 kWh | 6,934 kWh | £1,257 | £709 |
| 23% | 1,969 kWh | 6,591 kWh | £1,305 | £784 |
Self-consumption rates are MCS guidance note MGD 003's figures for a household using 2,500–2,999 kWh a year — 14% out all day, 19% in half the day, 23% home all day. They are averages for similar households, not a prediction for yours, and self-consumption falls as the array gets larger. Import is the price cap unit rate for 1 July to 30 September 2026. The two export columns are the best and the median open untied rate in our SEG table — the gap between them is what choosing an export tariff is worth, and it is larger than most people expect.
Who this size suits
- large properties, often rural, with barn or outbuilding roof area
- homes with a three-phase supply
- households with heat pump, EV and storage together
Roughly 24 panels at 430 W, needing about 48 m² of roof. Higher-rated modules need fewer panels for the same capacity, which matters on a tight roof.
Supply arrangement decides this
Single-phase. G98’s limit is 16 A per phase — 3.68 kW. A 10 kWp system is far above it, so this is a G99 application, and the operator will assess what the local network can take.
Three-phase. The same 16 A per phase converts to 11.04 kW across three phases, so a three-phase property has substantially more headroom before the process changes — a real advantage, and one that is worth establishing before design rather than after.
Either way, at this capacity the answer from the network operator is a genuine variable rather than a formality. Ask your installer to make the application early.
What the cost data shows at this size
Ten kilowatts sits at the top of the 4–10 kW band. The next band up, 10–50 kW, is cheaper again per kW — which tells you that the fixed-cost spreading continues well beyond domestic scale.
If your roof genuinely supports more than 10 kWp, it is worth asking for a quote at both sizes. The marginal cost per kW above 10 kWp is lower than the average below it.
Do not skip the roof
At this scale the array is a substantial load and area. A structural assessment is not a formality, and if the covering is anywhere near the end of its life, re-covering first is far cheaper than removing and refitting later.
Check the quote, not the brochure
Divide the quoted price by the array’s kWp and compare it with the published benchmark. Then check what the quote includes, and what it does not — the costs outside the headline are where budgets break.
Sources
- Solar photovoltaic (PV) cost data Release 2025-26, published 28 May 2026, Total Installed Capacity basis. Derived by the department from the MCS Installation Database.
- MGD 003: Solar PV Self-Consumption, issue 2.0 (1 April 2022) Read locally. MCS restricts reproduction, so we cite clauses and quote sparingly.
- Energy price cap unit rates and standing charges
Contains public sector information licensed under the Open Government Licence v3.0.
Sorry to hear that. What was the problem?