# How Much CO2 Does Commercial Solar Save?

A commercial solar system cuts carbon by generating electricity on site that would otherwise be drawn from the grid. The exact CO2 saving depends on how many kilowatt-hours the system produces each year and the carbon intensity of the grid it displaces, so it varies by system size, location and time of use.

## Where the carbon saving comes from

Every unit of electricity you generate and use on site is a unit you no longer buy from the grid. Grid electricity still carries a carbon cost because part of the supply comes from gas and other fossil generation. When your solar panels meet that demand instead, the emissions associated with that grid electricity are avoided.

This is why self-consumption matters for carbon as well as cost. Power you use directly displaces grid supply at the moment of generation. Power you export displaces grid demand elsewhere, which still helps, but the clearest carbon benefit comes from using your own generation on site.

## Why there is no single fixed figure

Two identical solar systems can save different amounts of carbon. A rooftop in the south of England generates more annual output than the same array in the north, so it displaces more grid electricity. The grid's carbon intensity also changes through the day and year as the mix of wind, solar, nuclear and gas shifts, so the emissions avoided per unit are not constant.

For an honest estimate, multiply your expected annual generation in kilowatt-hours by a published grid carbon intensity factor. The UK Government publishes conversion factors each year for exactly this purpose. Because both inputs change, treat any headline CO2 number as an estimate rather than a guarantee.

## Using the figure in reporting

If you report emissions under a framework such as SECR or a corporate net-zero commitment, on-site solar reduces the Scope 2 emissions tied to your purchased electricity. Keep your generation and consumption data, because credible reporting relies on measured output rather than an installer's brochure figure.

How you account for exported energy and any green tariff you also buy affects the numbers, so confirm the method with your accountant or sustainability advisor before publishing a carbon claim.

## Frequently asked questions

**Does exported solar power still save carbon?**

Yes, exported electricity offsets grid demand elsewhere, which reduces emissions across the network. The most direct and easily reported saving, though, comes from the power you generate and use on site rather than send back to the grid.

**How do I calculate my own CO2 saving?**

Take your system's estimated annual generation in kilowatt-hours and multiply it by the current UK grid carbon intensity factor published by the Government. This gives an annual figure in kilograms or tonnes of CO2. Confirm the method with your advisor for formal reporting.

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Source: [How Much CO2 Does Commercial Solar Save?](https://ppafunding.com/guides/how-much-co2-does-commercial-solar-save) · Author: PPA Funding team · Updated: 2026-07-30

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