Renewables have faced many challenges in their quest to penetrate mainstream energy markets. High costs and the whims of nature have always been the foremost among them. As renewable energy grows, add oversupply to the list.
The surge of renewable power in recent decades has created the added problem of too much electricity from wind and solar coming onto the grid. Experts and investors have frowned on building too much capacity that creates a need to cut back or curtail renewable energy production when there is excess generation.
A new study published in the journal Solar Energy turns this logic on its head. “Overbuilding and curtailment: the cost-effective enablers of firm PV generation” was published in March by researchers at Clean Power Research, the University at Albany and the Pace University Energy and Climate Center. They argue that, when done properly, curtailment and oversizing of generating capacity can help solar power reach its maximum potential.
Relying on mathematical models and incorporating data generated from a recent study of a utility-scale photovoltaic plant in Minnesota, the researchers conclude that over-building solar plants combined with what they describe as “proactive curtailment” will allow solar to perform like conventional power generating sources and at a competitive price.
The study also contradicts the conventional wisdom that solar can be effective only with a heavy investment in storage technology to bank power for use when the sun goes down. Instead, the researchers argue that overbuilding solar generation across a geographically dispersed area and managing it with proactive curtailment practices is a more cost-effective approach. Some storage will still be needed in the overall mix, along with a blending of wind power and natural gas, effective load balancing practices, and an improved grid.
The researchers also introduce the concept of “firm power,” which they define as power that can be dispatched to meet demand at any time with 100 percent reliability. Conventional fuel sources would be considered firm power, but solar power would not because it relies on the sun. However, the researchers argue that, with the balancing of oversupply and curtailment, solar can generate firm power at a competitive price.
While the study focused on data from the state of Minnesota, other states may be demonstrating the same results. Recently, the Los Angeles Times reported that California had reached two seemingly contradictory milestones at about the same time. The California ISO (CAISO) set an all-time instantaneous solar generation peak of 11,363 megawatts (MW) on June 1. CAISO also reported that, on May 27, solar plant operators shut off a record total of about 4,700 MW of capacity at the same time, which accounted for nearly 40 percent of the entire solar capacity installed on the California grid.