Can Solar Contribute to Grid Reliability? Yes, Says California ISO Official
The reliability of the grid is a hot topic given the contention of U.S. Energy Secretary Rick Perry and others who say renewable energy will destabilize rather than strengthen the grid.
Clyde Loutan, who is the California Independent System Operator’s (California ISO) senior advisor for renewable energy integration, believes otherwise. He contends that solar photovoltaic systems can make the grid more reliable.
“If you have renewables in the right place, it can help you integrate more renewables into the system,” said Loutan.
Loutan said so during a June 22 talk on advanced grid reliability and solar energy at the California Energy Commission.
What Loutan had to say is significant given that the California ISO manages the flow of electricity across power lines that make up 80 percent of California’s grid, as well as a small part of Nevada’s.
When lights turn on it is largely because of how the California ISO keeps power flowing from power lines and substations to homes, businesses and communities.
A crucial task at the California ISO is forecasting electricity demand and meeting that demand at lowest cost for sale to utilities.
The goal is to have renewable resources, like solar and wind, provide essential reliability services that have traditionally been provided by conventional resources such as nuclear power plants and gas-fired power plants.
There are challenges that come with solar power in a reliability role. One is how high levels of solar generation during midday hours contribute to an oversupply of energy when demand for power is low. This leads to the curtailment of power and thousands of photovoltaic systems going offline at the same time.
Seeking an answer is important given that forecasts predict there will be 12,000 megawatts (MW) of rooftop photovoltaic solar installed in California by 2020. The solution is adopting smart solar inverters and voltage regulators on photovoltaic systems, Loutan said.
Solar inverters convert the direct current output from photovoltaic systems to alternating current that can be used by the grid. Most solar systems currently use dumb inverters, which are passive and cannot adjust power output during oversupply events.
Smart inverters can adjust and prevent shutdowns during oversupply events, helping to avoid the massive simultaneous shutdowns that negatively impact the grid. This makes solar energy more stable and a better power source.
That contention was underscored by a study by the California ISO, First Solar and the National Renewable Energy Laboratory on a 300-MW First Solar utility-scale solar plant in the California desert.
The study, which was released in January, found that the adoption of smart solar inverters and other controls on solar photovoltaic systems can provide grid-friendly power and reliability to the grid and prevent mass solar system shutdowns.
