• Climate hub
  • 7 Oct 2021
  • 4 min read

Solar gets clever with clouds

By David Appleyard

Machine learning is being used to turn forecasting into ‘nowcasting’

'Nowcasting' could boost the efficiency and appeal of solar energy here and around the world. A UK start-up that Google has helped fund explains how it works and the benefits.

Flip on a light switch or the kettle and the expectation is that power is instantly available. But achieving that in practice is a major challenge for grid operators, especially as the proportion of intermittent renewable energy expands.

The big challenge with solar is that clouds are unpredictable. That means you need an additional power reserve to balance out the supply and demand of energy. To compensate for the ups and downs of power usage, grid operators use what’s called spinning reserve. Typically provided by gas turbines that can quickly spin up or down as required, most of the time spinning reserve is not used at full efficiency. Instead, these machines are left idling, kept hot and running but at very low efficiency. They burn gas and produce greenhouse gases just so they can step in at short notice if needed.

Now, a new approach to weather forecasting is offering a boost to solar power while cutting greenhouse gases too. By understanding exactly where and how the clouds are moving, we can better predict where and how much solar power will be generated.

UK-based Open Climate Fix (OCF) is using satellite imagery and machine learning to ‘nowcast’ changes in cloud cover and project that against the locations of solar farms – an approach that could improve solar forecasting accuracy over short horizons by up to 50%. The OCF model is currently being trialled in a project with the UK’s National Grid Electricity System Operator which is due to conclude at the end of next year. That project is backed by UK energy regulator Ofgem and a £500,000 (NZ$979,000) grant, and OCF has also received similar funding from Google.org to develop its technology.  

By increasing confidence in forecasts, we can reduce the use of spinning reserve; the potential is significant. OCF estimates that around 100,000 tonnes of carbon are generated per year on spinning reserve capacity in the UK alone. They argue this level of waste is completely unnecessary.

“Clearly there is a direct cost for the grid operators and for the environment, but also for the owners of solar projects. Because larger solar farms operate in a market environment, they need to purchase electricity on the short-term balancing market if they get caught out by unexpected cloud cover and that can be quite expensive,” explains Dan Travers, Chief Digital Officer and Co-Founder of Open Climate Fix.

Making the most of solar

New Zealand is making significant effort to increase its solar capacity. Genesis is looking to develop 750 GWh per annum of solar (2% of the country’s total generation) while independent company Lodestone is also building five solar projects. Cloudcasting offers an opportunity to maximise the positive impact of solar projects and provide more certainty for our energy suppliers. Overall, it could lower the commercial risk for solar, increasing investment and lowering the cost of capital.

“For countries like New Zealand, investing in solar becomes less risky, borrowing becomes less expensive. We get more solar in any particular market and we have less cost associated with existing thermal capacity used as spinning reserve,” says Travers.

“We are doing this all-open source and as a non-profit, so all of the coding we are putting out there is on an open hub and we want people to take these ideas and use them,” says Travers. He adds that by adopting smarter nowcasting tools and being open about the location and size of its solar capacity, countries like New Zealand, which is just starting its solar journey, have a great opportunity to deploy solar power to maximum effect.

Subscribe to get the latest news and articles in your inbox.

Related articles

Cars in traffic
  • Climate hub
  • 7 Oct 2021

Have we reached peak car?

New Zealand’s long love affair with cars seems to be on the decline – and it’s part of a global trend.

hydrogen tank for renewable energy
  • Climate hub
  • 16 Sep 2021

The hype on hydrogen

As demand for power grows green hydrogen can play a vital role for New Zealand

Four hands high fiving in nature
  • Climate hub
  • 21 Oct 2021

Hitting NZ's climate change targets

Words of advice for New Zealand’s Climate Change Commission from their UK counterpart.

Wind farm in China
  • Climate hub
  • 6 Oct 2021

China watch: coal on the rise

Whether the world meets emissions targets depends largely on China