Solar vs Extension: Which Adds More Value in 2026 UK?
It depends on your goal. A single-storey extension (£35,000–£70,000) typically adds £25,000–£55,000 of capital value plus real living space. Solar PV (£6,000–£10,000) adds a more modest £1,500–£4,000 to value, but cuts bills £400–£900 a year and earns export income. Extension wins on value and space; solar wins on percentage ROI and running savings. Here's the full comparison.
Solar vs extension — 2026 UK at a glance
- Best for capital value: Extension — adds £25,000–£55,000 and floor area.
- Best for percentage ROI: Solar — £6,000–£10,000 outlay, 7–12 year payback.
- Best for lower bills: Solar — £400–£900/yr saved plus SEG export income.
- Best for more space: Extension — a new kitchen-diner or bedroom.
- Lowest disruption & cost: Solar — 1–2 days on site vs 8–16 weeks.
Rule of thumb: extend if you need space and want resale value; go solar if you want the cheapest, fastest win on running costs.
Solar vs extension compared, 2026 UK
Value figures are indicative midpoints; regional comparables and buyer demand move them significantly. London & South East sees the largest extension uplift.
Which should you choose in 2026?
Choose an extension if you need more usable space, plan to stay several years, and want the largest uplift in your home's market value — accepting a bigger budget and 8–16 weeks of disruption.
Choose solar if you want the best percentage return on a smaller budget, lower energy bills now, and minimal disruption — accepting a modest effect on resale value.
Do both, in order: many homeowners fit solar first as a fast, cheap win, then extend later — designing the new roof to take panels and pre-running cabling to cut future retrofit costs.
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Frequently asked questions
An extension adds far more capital value — typically £25,000–£55,000 for a single-storey rear extension — because it adds floor area and a room. Solar PV adds a more modest £1,500–£4,000 but is much cheaper and cuts running costs.
Roughly £1,500–£4,000, or about 0.5–2% of value, depending on system size, battery and buyer appetite. The bigger financial benefit is £400–£900 a year off bills plus Smart Export Guarantee income.
As a percentage, solar usually wins — a £6,000–£10,000 outlay can pay back in 7–12 years through bill savings and export income. An extension rarely returns 100% of its cost on resale, but it adds space and quality of life solar can't.
£35,000–£70,000 for a typical 15–25m² single-storey rear extension, depending on spec, glazing and region. London and the South East sit at the top of the range.
Yes, and many homeowners do solar first as a cheaper quick win, then extend later. If you plan an extension, design the roof pitch and orientation to take panels, and pre-run cabling to avoid retrofit cost.
Most domestic solar is permitted development. Many single-storey extensions are too, within size limits, but larger ones need full planning permission. Conservation areas and listed buildings restrict both.
Sources used in this comparison
- Ofgem — Smart Export Guarantee (SEG)
- Planning Portal — Extensions
- MCS — Microgeneration Certification Scheme
Methodology: Cost, value and saving figures use representative 2026 UK quote and market data cross-referenced against Ofgem SEG rates and trade benchmarks. Value uplift is indicative and varies by region and comparables. Last fact-checked: .