Yes, solar reduces carbon emissions. The interesting questions are how much, how quickly a panel repays the energy used to make it, and how that changes as the grid itself gets cleaner.
The energy payback question
People ask whether it takes more energy to make a panel than it ever produces. It does not, and it has not for a long time.
A modern panel repays the energy used in its manufacture well within the first few years of operation, and then generates for decades. Manufacturing energy has fallen substantially as production has scaled and efficiency has improved, so figures from a decade ago overstate it considerably.
The objection was reasonable in the 1980s. It is not now.
The moving target: a cleaner grid
Here is the part most solar content avoids.
The carbon saving from solar depends on what your electricity would otherwise have come from. The UK grid has decarbonised substantially, with a large and growing share of generation from wind, solar and nuclear.
That means each unit of solar you generate displaces a cleaner unit than it would have ten years ago, so the carbon saving per unit is smaller than it used to be.
This is good news about the grid rather than bad news about solar, and we would rather say it than quote a carbon figure from 2015 that no longer holds.
When your solar is worth most, in carbon terms
Not all units are equal. The grid’s carbon intensity varies hour to hour depending on what is generating.
Solar generates in the middle of the day. In summer, when the grid is often already running on a lot of renewable generation, the marginal unit your solar displaces may be relatively clean. On a still winter evening, when gas is running to meet peak demand, the marginal unit is much dirtier.
Which is an argument for a battery Storing midday generation and using it in the evening displaces dirtier electricity than exporting it at midday does. The same logic that makes a battery pay financially also makes it better in carbon terms. See solar batteries.
Where the bigger carbon reductions are
If carbon is your main motivation, be aware that for most British homes, solar is not the largest available reduction.
Heating is The large majority of UK homes heat with gas, burning it directly. Electricity has decarbonised; gas has not. Replacing a gas boiler with a heat pump is generally a larger carbon reduction than adding solar, particularly in a home with high heating demand.
That is not an argument against solar. It is an argument for doing both, which is also where the financial case is strongest. See solar and a heat pump together.
Insulation comes before either, per pound spent, for a home that is losing heat.
What we are not going to do
Quote you a specific tonnes-of-CO2 figure It depends on your generation, your self-consumption, the grid’s carbon intensity at the times you generate and use, and how that intensity changes over the system’s life. Any single number would be a guess dressed up as a fact, and this category has enough of those.
If you want a current figure for grid carbon intensity, it is published and updated continuously by the people who run the system, and that is a better source than anything we could write here.
End of life
Panels reaching the end of their life can be recycled, and there is a growing UK recycling route. Manufacturers and importers carry obligations for end-of-life handling under electrical waste rules.
Worth knowing, though not something you need to plan for now.