Estimate how much you could save on electricity bills and earn through the Smart Export Guarantee (SEG) with rooftop solar panels. Based on PVGIS regional yields, Ofgem price cap rates and typical MCS-certified installs.
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EcoHome UK designs and installs MCS-certified solar PV systems. Solar is currently zero-VAT until 2027 — book your free survey now to lock in the saving.
Get a free survey →How is this calculated? (Methodology & sources)
All figures are estimates based on conservative published data. Actual output depends on roof pitch, shading, panel brand, inverter efficiency and your specific tariff.
Annual generation model: Generation (kWh) = system size (kWp) × regional base yield (kWh/kWp) × orientation factor. Base yields are derived from PVGIS (EU Joint Research Centre) and are consistent with MCS standards used by certified UK installers.
| Region | Base yield (kWh/kWp/yr) | Source |
|---|---|---|
| Southern England | 1,000 | PVGIS (south coast average) |
| Midlands & Wales | 950 | PVGIS (central UK average) |
| Northern England & Scotland | 850 | PVGIS (northern average) |
| Roof orientation | Factor applied |
|---|---|
| South-facing | 1.00 (full yield) |
| East–West split array | 0.90 |
| Single East or West face | 0.80 |
| North-ish (not recommended) | 0.65 |
Self-consumption fractions: The proportion of generated electricity used directly in the home (rather than exported) varies with occupancy.
| Occupancy pattern | Self-consumption fraction |
|---|---|
| Someone home most days | 50% |
| Mix of home and out | 40% |
| Out during the day | 30% |
Tariff assumptions:
- Import price: 25p/kWh — rounded down from the Ofgem Q2 2026 price cap unit rate for electricity. (Ofgem price cap)
- SEG export rate: 15p/kWh — a representative rate from competitive Smart Export Guarantee tariffs. Actual SEG rates vary by supplier; some offer up to 24p/kWh on the best tariffs. (Ofgem SEG)
Indicative install costs used for payback calculation:
| System size | Indicative cost (inc. VAT at 0%) |
|---|---|
| 3 kWp (small) | ~£5,000 |
| 4 kWp (medium) | ~£6,000 |
| 6 kWp (large) | ~£8,000 |
| 8 kWp (very large) | ~£10,000 |
Solar PV panels and installation are currently zero-rated for VAT in the UK until at least March 2027. Payback = indicative cost ÷ annual benefit. Lifetime is 25 years (typical panel warranty period). No battery assumed — adding a battery improves self-consumption and can materially reduce payback.
Sources: PVGIS (EU JRC) solar resource database, MCS — Microgeneration Certification Scheme, Ofgem electricity price cap, Ofgem Smart Export Guarantee.
This calculator is for guidance only. Actual savings depend on your roof, shading, occupancy, panel specification and the tariff you choose. Request a free survey for a site-specific assessment.
What is the Smart Export Guarantee (SEG)?
The Smart Export Guarantee (SEG) is a UK government-backed scheme that requires larger energy suppliers to pay you for surplus electricity you export back to the grid. Unlike the old Feed-in Tariff, the rate is set by each supplier competitively — currently ranging from around 1p/kWh (some standard tariffs) up to 24p/kWh on the best specialist offers.
You must have a smart meter to receive SEG payments. SEG is available to any home with an MCS-certified solar installation up to 5 MW in capacity. EcoHome UK installs are MCS-certified and SEG-eligible.
For the best return, pair solar with daytime appliance use (dishwasher, washing machine, EV charging) and consider a battery to store excess generation for evening use — this can raise self-consumption from ~30% to 70%+.