Open Climate Fix’s solar PV forecast saves Great Britain’s National Energy System Operator (NESO) over £30m per year through delivering a 50% increase in forecast accuracy. But with better access to real-time solar generation data, we could make forecasting even more accurate, reduce the cost of balancing the electricity system and give the control room greater confidence in its decisions.

Balancing the grid is hard. NESO needs to constantly ensure the supply of power is matched at every instant with the demand. To do this NESO needs lots of information about all the devices generating, consuming or storing electricity.

With the growth of distributed energy devices such as EV chargers, rooftop and plug-in solar, heat pumps and batteries, there is much more activity happening at the grid edge which is not visible to NESO. Most solar generation in the UK comes from small and medium-scale assets - medium sized solar farms and rooftop solar. Because this generation isn’t registered as a large generation source, NESO doesn’t have any readings of what they generate in real-time or historically, so has a very limited view of when and where solar power is actually being generated.

Millions of solar panels across the UK are generating electricity, but almost all of that generation is effectively invisible to the network. This means that the solar generation figures used by the network is based on models, rather than metered data. Sheffield Solar has stepped in to help address this challenge. They use readings from over 25,000 domestic rooftop installations to create the best estimate we have for half-hourly solar generation in the UK. But their solar generation modelling is based on live data from around 0.3% of the UK's actual solar capacity.

Everyone on the electricity market, from generators to suppliers, are trying to purchase the right amount of electricity at the right time. Not knowing how much solar electricity is being generated makes this more costly and risky.

While it is hard to know all these costs, for NESO, low visibility of solar generation means greater risks to manage. Back-up reserves must be running in case solar output suddenly drops. NESO keeps fossil fuel generation on standby to cover that uncertainty and pays more to balance the system. NESO spends around £2bn a year balancing the grid, and this is projected to rise to £8bn by 2030. Billpayers are burdened with these costs. While solar uncertainty is not the majority of these costs - it is an unnecessarily large portion.

NESO calculated that OCF’s solar forecast already saves billpayers £30m a year. This could rise to £120m* if our forecasts could be developed using better data on when and where solar power is generating electricity, diminishing unpredictability. These savings would translate to energy bill reductions.

With more real-time solar generation data available in the UK:-

A collaborative approach is needed to achieve these benefits. By working together, innovators, DNOs, NESO, the Government, solar installers and other actors will be able to get a better picture of solar generation, how it can be used to harness the full potential of AI, and revolutionise the way we manage our electricity grid.

The UK is building more solar every year. We need to make sure NESO and the wider industry can see what that generation is doing. Better recording of all the solar panel installations would help. Solar generation readings should be shared and made accessible for the operators responsible for balancing the system and keeping the lights on. For a renewable-led system to live up to its huge potential, data must be usable by those who need it.