What happens to excess solar power generated?

When too much energy is produced by solar panels to meet the immediate needs of the property, the excess power will either get exported and sold back to the grid, or if there is a battery, then it will get stored until needed.

Understanding solar power generation

Solar power works by converting sunlight into electrical energy. This occurs because of the photovoltaic cells in the solar panels absorbing sunlight which causes them to release electrons and produce an electric charge. This charge generates a direct current (DC), which flows into the inverter and is converted into alternating current (AC) which is used to power appliances.

Selling excess solar power to the grid

For commercial, industrial and agricultural businesses that have installed solar PV systems that are likely to export in excess of 15,000kWh per annum to the grid, energy companies are keen to purchase this energy. This requires an export meter and contract to be setup and a contract rate for the export to be agreed. In the UK today, the current export rate in this scenario is approximately 7p/kWh. In some cases, especially when the export volumes are low, the fallback position should you wish to be paid for your excess electricity is the government-backed Smart Export Guarantee (SEG) initiative. Solar panel owners can apply for SEG and will be paid for every unit of electricity that is unused by themselves and therefore fed back into the grid. The SEG rate purely for Export contracts i.e. you don’t have an Incoming Supply arrangement with the same supplier is usually around 4-5p/kWh. There are higher payments available, primarily to residential customers that commit to sourcing their household energy from the export provider. This extra income allows owners to see the financial benefits that solar panels have to offer. Selling excess solar power to the grid enhances the promotion of environmental conservation due to the excess energy being able to channel onto other properties. This effectively reduces the UK’s need for fossil fuels; one of the leading causes of climate change. Despite the scheme that is now in place only paying back for exported electricity, there are many benefits of utilising the SEG scheme including: extra income, reduced energy bills and maintaining a stable grid network by helping to balance the supply and demand for electricity across the UK. Overall, implementing a solar panel system enables businesses to contribute to a greener future, save money on their energy bills and generate additional income simultaneously.

Solar power export incentives

A solar power export incentive is a scheme that enables people to earn money for exporting clean energy that is generated from their solar panel system. Before the Smart Export Guarantee (SEG) was introduced, the government launched the Feed-In-Tariff (FIT) policy in 2010, which had a purpose to enhance low-carbon electricity and take strides in the Net Zero 2050 strategy . It enabled the movement of national investments in renewable energy generation systems by obligating energy suppliers to pay solar panel owners for both the generation and exportation of clean electricity. The Smart Export Guarantee (SEG) replaced the Feed-In-Tariff (FIT) in 2020 which requires certain energy suppliers to pay small-scale generators for the electricity they export back to the grid.

Battery storage systems

Battery storage systems can be put in place to store excess solar energy, however, you then lose the income from any energy that would have been exported. The power can then be used when it is needed most, such as during power outages or when a business is experiencing a high consuming period, overall keeping costs down and green electricity running.
The ‘use case’ and capital costs need to be carefully assessed for battery, as if you intend to use your battery for backup during power outages, you need to ensure your battery always has:

a) enough charge to provide power for the defined amount of time for the electrical equipment it is required to power, and

b) that the battery can discharge at a rate that meets the demands of the electrical equipment and plant requires it.

According to the National Grid, battery storage systems will start to play a critical role in the process of replacing the need for fossil fuels due to the good response to electricity demands. If we can store electricity for later use when the supply is perhaps lower or need extra to meet demand, battery storage enables us to keep costs down and decarbonise concurrently. The government estimates that battery storage systems can contribute to saving the UK energy system up to £40 billion by 2050, in turn reducing the country’s utility bills overall.

What happens to excess solar power if it isn't stored or sent to the grid?

If excess solar power is neither stored for later use nor exported back to the grid, it essentially is wasted energy. Because of the solar panel system’s inability to switch off, if there is too much generation to meet the needs of a property, the energy will practically disappear. Even though this will have no major impact, it demonstrates the benefits of selling excess solar power to the grid or utilising a battery storage system to maximise the potential that solar can offer, particularly highlighting the financial and environmental impacts.

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