On the morning of 21 August, an eclipse is set to cast a shadow across North America, blocking the sun entirely in parts of Oregon, Idaho, and Wyoming. However, it is further south, in California, where the eclipse is causing the most head-scratching. The US’s most populous state has been at the sharp end of the global solar revolution, with over 2,000MW of solar capacity being installed annually for the past four years (in March, so much power was produced that wholesale electricity prices turned negative). However, with the eclipse set to block solar rays by up to 76 per cent at the peak of the three-hour transition, commercial solar production is likely to drop from around 9,000MW, to an estimated 3,000MW. ‘The last total solar eclipse visible in North America was in 1979, a time when solar energy technology was barely emerging,’ explains Anne Gonzales, spokesperson for the California ISO (Independent System Operator).
For those tasked with keeping the lights on amid the darkening skies, the strategy is focused on reducing demand. ‘If millions of Californians turn off appliances and power strips to unplug from the grid during the eclipse, we can let our hard working sun take a break,’ announced Michael Picker, president of the California Public Utilities Commission. Nevertheless, Gonzales confirms that the state will be coordinating with companies supplying gas and hydropower in order to meet demand. ‘These resources will be key to supplying generation going into the eclipse,’ she adds, ‘and continuing to help us maintain load-resource balance by reducing generation as we come out of it.’
There is precedent for such a scenario; two years ago, central Europe was briefly overshadowed by a passing eclipse, which caused a headache for energy suppliers in Germany – another leading solar producer – an experience California has been keen to learn from. ‘But each eclipse has unique qualities,’ points out Gonzales, ‘such as the geographical path and totality of coverage, the proximity to generation, and the weather.’
Thankfully for the Golden State, the next disruptive major eclipse isn’t scheduled to arrive until 2045.
This was published in the July 2017 edition of Geographical magazine.