Utility-scale solar generation in the Golden State accounted for almost 40 per cent of net grid power on 11 March, pushing wholesale prices into the negative
The success of solar deployment in the sunny state of California has sent power prices in the region dipping into the negative.
On 11 March utility-scale solar generation accounted for almost 40 per cent of net grid power produced during the hours of 11am-2pm - a new record - data from the California Independent System Operator (CAISO) shows.
The amount of solar capacity in California has grown so much over the last year that it has occasionally driven prices on the CAISO power exchange to very low, and sometimes negative, prices during late winter and early spring daylight hours .
A combination of longer days and lower overall electricity demand during late winter and early spring contributed to the high proportion of solar PV generation, according to the US Energy Information Administration (EIA).
"Consequently, power prices on both the day-ahead and real-time CAISO markets were substantially lower in March compared with other times of the year or even March of last year," the EIA explained. "Negative prices usually result when generators with high shut-down or restart costs must compete with other generators to avoid operating below equipment minimum ratings or shutting down completely."
Nevertheless, the EIA said bill payers in California continue to pay average retail electricity prices in the state, which are among the highest in the USA.
Overall, solar capacity in California - including both utility-scale and smaller, residential installations - has grown over the past decade from less than 1GW in 2007 to almost 14GW by the end of last year.
In related US clean energy news, meanwhile, Chicago Mayor Rahm Emanuel has pledged that all public buildings in the city will be powered by 100 per cent renewable energy by 2025.
Reaching the target would make Chicago the largest major city in the US to have a 100 per cent renewable energy supply for its public buildings, the mayor said, with the city's public schools, housing authorities, city colleges and other buildings using nearly 1.8 billion kWh of electricity in 2016 - almost eight per cent of all electricity use in the city.
Emanual said the commitment would be met through a combination of acquiring renewable energy credits, utility-supplied renewable energy via the Illinois state Renewable Portfolio Standard, and on-site generation, with initial purchases beginning in 2018 and 2019.
"As the Trump administration pulls back on building a clean energy economy, Chicago is doubling down," Mayor Emanuel said. "By committing the energy used to power our public buildings to wind and solar energy, we are sending a clear signal that we remain committed to building a 21st century economy here in Chicago."
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