A 2 kW solar system: cost and output
Two kilowatts is the point at which the fixed costs of an installation — scaffolding, the visit, the inverter, the paperwork — are spread across the fewest panels. It is the most expensive solar per unit you can buy, and sometimes it is still the right answer.
| Roughly how many panels | 5 at 430 W |
|---|---|
| Published size band | 0-4 kW |
| Installed cost, median | £3,190 (£1,595/kW) |
| Installed cost, mean | £3,617 (£1,808/kW) |
| Generation, south-facing at 35° | 1,712 kWh a year for a median location; 1,384 to 2,084 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% | 240 kWh | 1,472 kWh | £239 | £123 |
| 19% | 325 kWh | 1,387 kWh | £251 | £142 |
| 23% | 394 kWh | 1,318 kWh | £261 | £157 |
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
- small roofs, dormer bungalows and properties where a larger array simply will not fit
- households with genuinely low consumption, where a larger array would mostly export
- a first stage where the roof or the budget will not take more today
Roughly 5 panels at 430 W, needing about 10 m² of roof. Higher-rated modules need fewer panels for the same capacity, which matters on a tight roof.
The problem with small
A solar installation has a large fixed component. Scaffolding costs what it costs whether it carries five panels or fifteen. So does the survey, the electrical connection, the certification and the visit.
At 2 kWp you are paying that fixed component across about five panels, which is why the published cost per kW at the bottom of the range is the highest on this site.
The practical consequence: if the roof will take more and you can use or export the output, going bigger almost always improves value per pound. Ask what four more panels cost — the answer is usually much less per panel than the first five, for exactly this reason. See cost per kW.
When 2 kW is still right
When the roof will not take more. No amount of arithmetic beats a small roof.
When consumption is genuinely low. A household using 1,500 kWh a year will export most of what a 4 kWp array makes, and export is worth a fraction of what avoided import is worth. A smaller array with high self-consumption can be better value than a larger one with low self-consumption.
When it is a deliberate first stage — though be careful here: coming back later means scaffolding twice, and two visits cost more than one. If the plan is to expand, it is usually cheaper to do it now.
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.
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