Plug-In Solar Cost per kWh vs Grid Electricity (UK 2026)
How does the levelised cost of plug-in solar electricity compare to what you pay your supplier? Updated for Q3 2026 tariffs.
Levelised Cost of Energy (LCOE)
The LCOE divides total system cost by total lifetime energy production to give a cost per kWh. For plug-in solar:
800W System LCOE Calculation
| Factor | Value |
|---|---|
| System cost | £600 |
| Annual generation | 850 kWh |
| Panel lifespan | 25 years |
| Degradation | 0.5%/yr |
| Maintenance | £10/yr |
| Total lifetime generation | ~19,500 kWh |
| Total lifetime cost | £850 (system + maintenance) |
| LCOE | ~4.4p/kWh |
How That Compares to Grid Electricity
| Source | Cost per kWh |
|---|---|
| Plug-in solar | 4.4p |
| Ofgem cap (Q3 2026) | 24.5p |
| Cheapest fixed tariff | ~21.5p |
| Octopus Agile peak | 35p+ |
| SEG export rate | 3-6p |
Plug-in solar electricity costs roughly one-fifth of grid electricity. Even accounting for the fact that you can only use it during daylight hours, it's dramatically cheaper.
The Self-Consumption Catch
The LCOE only matters for electricity you actually use. If you export most of your generation at 4p/kWh, the economic benefit is minimal. This is why maximising self-consumption is crucial.
| Self-consumption | Effective value per kWh generated |
|---|---|
| 30% (mostly away) | ~10p |
| 55% (average) | ~15p |
| 75% (mostly home) | ~20p |
| 90% (optimised) | ~23p |
Real-World Savings Calculation
For an average household (55% self-consumption):
- Each kWh generated saves: 0.55 × 24.5p + 0.45 × 4p = 15.3p
- Annual generation: 850 kWh
- Annual value: 850 × 15.3p = £130
- Payback on £600 system: 4.6 years
- 800W dual-panel plug-in solar kit
- 600Wh battery with smart scheduling
- App monitoring with real-time generation data
- Balcony, garden & flat-roof mounts available
Does LCOE account for inverter replacement?
Our calculation assumes the inverter lasts 15+ years. Modern microinverters have 10-25 year warranties. If replacement is needed at year 15 (~£150), LCOE rises to ~5.2p/kWh — still dramatically below grid price.
How does UK plug-in solar LCOE compare internationally?
UK LCOE is higher than southern Europe (more sun = more kWh for the same cost) but competitive with Germany and the Netherlands, where plug-in solar is already mainstream.
Related reading
See how much plug-in solar could save you — with real data for your postcode.