Generating electricity from solar panels does not produce greenhouse gases directly – but emissions arise during other parts of their life cycle such as manufacture and transport.
The carbon footprint of a solar photovoltaic (PV) panel – how much greenhouse gas it emits during its working lifetime – is about 88 grams of carbon dioxide-equivalent per kilowatt-hour of electricity generated (gCO2e/kWh), according to government statistics.
The main components of solar PV panels are made from crystalline silicon. Manufacturing these components is an energy-intensive process that accounts for 60% of the total energy used to make solar panels. The exact carbon footprint of any particular solar panel depends on many factors: the source of the materials, the distance they must be transported, and the energy source used by the manufacturing plant.
China is a leading producer of solar PV panels where a lot of electricity generation is from coal-fired power stations – contributing to the carbon footprint of solar panels made there.
Solar panels do not create carbon emissions during operation. Theoretically therefore, each kilowatt-hour (kWh) generated by solar power is one not generated from a more carbon-intensive fuel.
The UK climate is not well suited to large-scale solar electricity generation. Solar technology is typically used by individual businesses and homes, and in devices such as road signs to generate instant energy. A typical photovoltaic (PV) system (2kW) can generate about 50% of a home's annual electricity needs – saving up to one tonne of carbon dioxide each year. However generation from the sector system may not always occur when the home owner requires electricity.
When considering climate change, the main drawback of solar energy is the energy used to make solar panels. New thin-film silicon is being developed as a cheaper and low-carbon alternative to conventional PV cells. And new semiconducting materials such as organic cells and nano-rods are also being researched.
Recycling and reuse of materials is another way to reduce the carbon footprint of solar energy. Producers are being encouraged to take responsibility for the lifecycle impact of their products: increasing the recovery and reuse of silicon, aluminium, copper and glass. The semiconductor materials themselves can also be recovered and reused in new PV cells or other products.