Levelised Cost of Energy
Levelised Cost of Solar UK — Commercial PV 2026
UK commercial solar produces electricity at 5.5–8p/kWh — versus grid commercial electricity at 28–32p/kWh. The crossover passed in 2018; the gap has widened every year since.
LCOE — Levelised Cost of Energy — is the single most useful number for any CFO or finance director evaluating commercial solar. It tells you what each kWh of self-generated electricity actually costs over the system's life, fully loaded with capital, O&M, and degradation. UK commercial solar LCOE in 2026 is 5.5–8p/kWh — a fraction of the 28–32p/kWh paid for grid commercial electricity.
5.5–8p
UK rooftop LCOE
4.5–6.5p
UK ground-mount LCOE
28–32p
UK grid electricity
~5×
Grid : solar ratio
What Is LCOE — and Why It Matters
LCOE = (total lifetime cost of the energy system) ÷ (total lifetime energy produced). The output is a £-per-kWh figure that is directly comparable to grid electricity tariffs.
For commercial solar, LCOE is the answer to "what does each unit of solar electricity actually cost me?" — fully loaded with capital, operations, maintenance, inverter replacement, monitoring, and panel degradation across the full 25-year system life. It is the metric your CFO will care most about.
UK Commercial Solar LCOE — 2026 Numbers
Based on our installed-fleet performance data and published UK tier-1 panel + inverter pricing (May 2026):
| System type | Capital £/kWp | 25-yr O&M £/kWp | Annual yield kWh/kWp | LCOE p/kWh |
|---|---|---|---|---|
| Rooftop, 50–250kW | £800–£950 | £250–£375 | 900–1,000 | 5.5–8p |
| Rooftop, 250kW–1MW | £700–£850 | £200–£300 | 900–1,000 | 4.5–6.5p |
| Ground-mount, 500kW+ | £600–£750 | £150–£250 | 1,000–1,100 | 4–6p |
| Solar carport | £950–£1,150 | £300–£400 | 900–1,000 | 7–10p |
How LCOE Is Calculated — The Full Methodology
For a UK commercial 100kWp rooftop solar system installed in 2026:
- Capital cost: £90,000–£115,000 (£900–£1,150/kWp depending on panel choice and site complexity)
- Annual O&M cost: £900–£1,500/yr (£9–£15/kWp/yr — covers monitoring subscription, annual inspection, cleaning, fault remediation)
- One inverter replacement at year 12–15: £8,000–£12,000 (string inverters last 12–15 years)
- Annual generation: 95,000 kWh year 1, declining at 0.5%/year (panel degradation)
- System life: 25 years (warranted), 30+ practical
The LCOE formula in plain terms:
LCOE = (Capital + 25-year O&M + inverter replacement) ÷ (25 × Annual generation × degradation factor)
Working through the numbers for a 100kWp rooftop:
- Capital: £100,000
- 25-year O&M: £30,000 (£1,200/yr × 25)
- Inverter replacement (year 12): £10,000
- Total lifetime cost: £140,000
- 25-year cumulative generation (with 0.5%/yr degradation): ~2,250,000 kWh
- LCOE: £140,000 ÷ 2,250,000 = 6.2p/kWh
LCOE by UK Region
UK regional irradiance varies from ~820 kWh/m² in northern Scotland to ~1,100 kWh/m² on the south coast — a ~25% range that flows through directly to LCOE:
| Region | Annual yield kWh/kWp | Rooftop LCOE | Ground-mount LCOE |
|---|---|---|---|
| South coast (Cornwall, Sussex, Hampshire) | ~1,000 | 5.5–6.5p | 4.5–5.5p |
| South East (London, Kent, Surrey) | ~970 | 5.7–6.8p | 4.7–5.7p |
| Midlands (Birmingham, Nottingham, Leicester) | ~950 | 5.8–7p | 4.8–5.8p |
| East of England | ~970 | 5.7–6.8p | 4.7–5.7p |
| North West (Manchester, Liverpool) | ~900 | 6.2–7.5p | 5.2–6.5p |
| Yorkshire / Humber | ~920 | 6–7.3p | 5–6.3p |
| North East (Newcastle, Sunderland) | ~890 | 6.3–7.5p | 5.3–6.5p |
| Wales (Cardiff, Swansea) | ~950 | 5.8–7p | 4.8–5.8p |
| Scotland Central (Glasgow, Edinburgh) | ~860 | 6.5–8p | 5.5–7p |
| Scotland North | ~800 | 7–8.5p | 5.5–7p |
Even at the highest LCOE in the table (Scotland North at 8.5p/kWh), commercial solar is still 27–35% of the grid cost.
LCOE With Tax Relief Applied
Standard LCOE methodology excludes corporation tax. For UK limited companies claiming the Annual Investment Allowance (100% first-year deduction at 25% corporation tax; full expensing does not apply to solar), effective LCOE drops a further ~25%:
| Build type | Standard LCOE | Effective LCOE post-AIA |
|---|---|---|
| Rooftop 100kW Midlands | 6.2p/kWh | 4.7p/kWh |
| Rooftop 250kW Midlands | 5.5p/kWh | 4.1p/kWh |
| Rooftop 1MW Midlands | 5.0p/kWh | 3.8p/kWh |
| Ground-mount 1MW Midlands | 4.5p/kWh | 3.4p/kWh |
For a 1MW ground-mount system, effective post-tax LCOE of 3.4p/kWh is just 11% of grid electricity at 30p/kWh.
Sensitivity — What Changes LCOE
The biggest drivers of LCOE on a UK commercial installation, ranked by impact:
- System size. Larger systems amortise the same fixed costs (DNO application, design, mobilisation) across more kWh. A 1MW system has ~30% lower LCOE than a 50kW system.
- Regional irradiance. Scotland North vs South Coast = ~25% LCOE delta.
- Roof condition / mounting type. Standing seam clamp = lower install cost; complex flashings on multi-pitch tiled roof = higher.
- Capital structure. Capital purchase + AIA = lowest LCOE. Asset finance adds 0.5–1p/kWh of interest cost. PPA = LCOE not your concern, but you pay typically 10–15% above the underlying LCOE to the PPA provider.
- O&M strategy. Self-managed monitoring + ad-hoc remediation: ~£8/kWp/yr. Full O&M contract with response SLAs: ~£15/kWp/yr.
- Panel degradation curve. Tier-1 monocrystalline (0.4–0.55%/yr) outperforms older PERC (0.5–0.7%/yr). Half-percentage-point delta = ~0.2p/kWh LCOE.
- Discount rate assumption. Standard LCOE uses an undiscounted simple sum. Discounted-LCOE at 5% WACC is ~10% higher than undiscounted.
LCOE vs Grid Electricity — The Crossover Curve
The UK grid commercial electricity price has roughly tripled since 2020:
- 2020: ~13p/kWh average
- 2022: ~25p/kWh (gas crisis peak)
- 2024: ~28p/kWh
- 2026: ~30p/kWh
Solar LCOE has fallen across the same period:
- 2020: ~9–11p/kWh
- 2022: ~7–9p/kWh
- 2024: ~6–8p/kWh
- 2026: ~5.5–8p/kWh
The grid:solar ratio has gone from ~1.4× in 2020 to ~5× in 2026. Every commercial property with a viable roof now has a textbook positive-NPV solar opportunity.
Why LCOE Is the Right Metric (Not Payback)
Simple payback (capital ÷ year-1 saving) is the most-cited solar metric — but it's the wrong primary metric for finance directors. Three reasons:
- Payback ignores the 20+ years of value after payback. A 4-year payback on a 25-year asset means 21 years of pure margin.
- Payback ignores time value of money. LCOE doesn't either at the simplest version, but discounted LCOE does.
- Payback can't be compared to grid tariffs directly. LCOE can. "Solar at 6p/kWh vs grid at 30p/kWh" is the cleanest possible board-paper line.
Use payback for the buyer's intuition. Use LCOE for the finance director's comparison. Use IRR/NPV for the capital allocation case.
Get Your Site-Specific LCOE
The LCOE numbers above are fleet averages. For your specific building:
- Send 12 months of half-hourly meter data + building postcode
- We model in PVSyst against your actual roof orientation, shading, and irradiance
- We return a site-specific LCOE in £/kWh, year-by-year cashflow model, IRR, NPV, and payback
- Free, no commitment, 5 working days turnaround
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