Record Breaking Solar Generation

A week of clear skies and warm temperatures has seen the UK break its all-time record for solar PV generation twice in as many days.

National Grid reported a new all-time peak for solar generation on Monday 13 May at 9.47GW. This surpassed the previous record which had held for two years, when supply hit 9.38GW in May 2017.

This record was then broken again the following day, when output peaked at 9.55GW on Tuesday 14 May. On that day, at its peak, solar generation was producing 27% of UK electricity.

Peak solar generation has averaged 8.7GW since Saturday as temperatures climbed over the weekend and weather conditions turned significantly brighter. The previous week when conditions were far cloudier, generation peaked at less than 5GW on average.

Growth in Solar Capacity

The new record for solar generation has come despite minimal growth in installed solar capacity in recent years. Total installed solar capacity has risen by just 0.5GW since April 2017, following the closure of the Renewables Obligation subsidy scheme. Total capacity is currently 13GW, having grown nearly 10GW in the three years from 2014 to 2017.

Impact on Demand

Solar output has a narrower window of generation than other fuel sources. High levels of solar generation during daylight hours are more impactful on reducing system demand, both the overall daily peak and the afternoon low. Solar generation raises the volume of embedded electricity, in which homes and businesses are generating their own supply via solar panels. Embedded generation removes the demand for that electricity from the transmission network. The higher the availability of embedded generation the lower the system demand. This is why the transmission network sees a sizable reduction in consumption across the middle part of the day, when solar output is at its strongest.

During the record solar generation on Tuesday, demand on the transmission network saw a drop of more than 6GW from the early morning high. Consumption dropped to just 25GW before climbing again for the post-work peak.

Peak electricity demand on the network is at record lows and is forecast to fall even further as the summer season progresses. 2019 as a whole has seen peak consumption trend lower than previous years, reflecting the greater efficiencies and renewable availability on offer. In the last week of May, a half-term school holiday, electricity demand is forecast to peak at just 31GW, an all-time low.

A Benefit to All Customers

In addition to the environmental advantages of renewable generation, distributed solar provides many benefits to the grid and by extension to all electricity consumers. Reduced demand on the system improves grid security and the often onsite nature of solar generation leads to less losses in electricity.

The demand reductions caused by higher levels of distributed solar generation, mean that less fuel is being used to power the electricity network. As demand falls wholesale prices fall,  the less efficient gas plants are no longer required so overall cost of generation is lower. These dips in demand means that hourly prices for the early afternoon are now on at similar levels to the prices normally recorded in the middle of the night. As more solar reduces prices in the daylight hours the cumulative effect of all the additional generation is to bring prices lower.

The government is currently analysing feedback on the proposal for a Smart Export Guarantee (SEG), designed to replace the now-closed Feed-in Tariff. This scheme would legislate for suppliers to provide tariffs to pay small-scale low-carbon generators, such as solar panel owners, for the electricity they export to the grid. Some suppliers have already begun to offer tariffs, based on the same concept, to incentivise the export of solar power to the grid.