The carbon math, in your own postcode.
Live regional grid intensity from National Grid ESO, regional generation figures from MCS / PVGIS averages, and a transparent payback calc. Type your outward postcode and pick a system size — we'll work the rest out and show our working.
Your postcode, your numbers.
We hit the regional Carbon Intensity API for live g/kWh in your area, then multiply by an annual generation estimate keyed to your region's average solar yield. Same maths the article walks through — just with your variables.
Live regional intensity: National Grid ESO Carbon Intensity API · Generation yields: EU Commission PVGIS regional kWh/kWp averages · Embodied carbon: peer-reviewed LCA ranges (silicon panels, inverter, mounting).
How we calculate annual savings.
The headline number is two figures multiplied together. Honestly. The work is in being honest about both.
- 01Annual generation (kWh) — kilowatts your panels produce in a year. We use the regional MCS yield: roughly 950 kWh/kWp/yr in the South East, dropping to 750 in north Scotland. A 4 kW system in Brighton therefore makes around 3,800 kWh.
- 02Grid carbon intensity (gCO₂/kWh) — the carbon released for each kWh you'd otherwise have bought from the grid. The UK average has fallen from ~520 in 2014 to roughly 165 today (and it keeps dropping).
- 03Multiply. 3,800 × 165 = 627,000 g = 627 kgCO₂/year. Done.
- 04Translate. A mature broadleaf tree absorbs ~22 kgCO₂/year. UK average car emits ~313 g/mile. So 627 kg ≈ 28 trees ≈ 2,000 petrol miles.
Manufacturing carbon isn't free either.
Solar panels embody carbon to make. A typical 4 kWp UK install carries 5–7.5 tonnes of embodied CO₂. That's the number you have to "pay back" before you're net-positive — and in the UK, you do.
| Component | CO₂ cost (per kW unless noted) | Notes |
|---|---|---|
| Silicon PV panels | 1,200–1,800 kgCO₂/kW | Mono-Si, current generation |
| Inverter (lifetime) | 300–500 kgCO₂ | One unit per system |
| Mounting / racking | 150–300 kgCO₂ | Aluminium-dominated |
| Cabling, isolators, MCBs | ~50 kgCO₂ | Copper + plastics |
| Battery (10 kWh, optional) | +1,500–2,500 kgCO₂ | LFP chemistry |
| Total · 4 kWp without battery | 5,000–7,500 kgCO₂ | Mid-range estimate |
Ranges sourced from the Fraunhofer ISE Photovoltaics Report and the IEA PVPS Task 12 life-cycle assessments. Real numbers vary with manufacturer, country of origin, and shipping route - we'll quote panel-specific figures on the survey.
Where you live moves the needle.
South-facing in Cornwall and south-facing in Caithness aren't the same job. A 4 kWp system has ~30% more output in the South East than in Northern Scotland, and the local grid mix swings the displaced-carbon figure further.
| Region | Annual yield (4 kWp) | Annual CO₂ saved | Carbon payback |
|---|---|---|---|
| Cornwall & Devon | ~3,900 kWh | ~870 kg | 6.5 years |
| South East (us) | ~3,800 kWh | ~840 kg | 6.7 years |
| South West / London | ~3,700 kWh | ~820 kg | 6.9 years |
| Midlands | ~3,500 kWh | ~770 kg | 7.3 years |
| North England | ~3,200 kWh | ~700 kg | 8.0 years |
| Scotland | ~3,000 kWh | ~660 kg | 8.5 years |
Figures use a mid-range 6,000 kg embodied carbon for the panels and assume a 220 g/kWh grid intensity. Use the postcode tool above for live numbers - the grid is dropping ~5% per year per National Grid ESO data, which keeps shrinking the payback period.
Over 25 years it isn't close.
A typical 4 kWp install in the South East: ~6 tonnes embodied, ~840 kg/year saved. After year 7 you're paying down emissions debt; after year 25 (the warrantied lifetime), you're net-negative roughly 15 tonnes of CO₂. That's the equivalent of a small car taking 100,000 miles off the road, or a woodland of ~700 mature trees breathing for a year.
And the grid keeps decarbonising — every year your panels displace a slightly cleaner kWh, but the absolute carbon-saved figure shrinks while the emissions-saved figure for the planet still rises. The honest answer to "is solar worth it for the climate?" in the UK in 2026 is yes, by a wide margin.
Anything technical?
Get in touch.
Tell us about the roof, the goal, or the problem. We'll reply by the next working day — usually faster.