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Modern solar power plants can be operated flexibly to respond to dispatch instructions, and they should be used to provide essential grid reliability services so less conventional fossil-fueled generation is needed for that purpose, according to a new study.

The Energy and Environmental Economics Inc., or E3, study, which was sponsored by First Solar Inc. and released Oct. 24, found that solar resources can be incorporated into a utility’s real-time dispatch decisions. Incorporating solar in such a way reduces fuel and maintenance costs for conventional generators and cuts air emissions, and those advantages grow as the level of solar penetration increases, the study, entitled “Investigating the Economic Value of Flexible Solar Power Plant Operation,” said.

Utility-scale solar facilities typically are designed and operated to deliver the maximum amount of electricity in real-time as “must take” resources, which means all the energy they produce is used as it becomes available. When operated in that way, solar must be balanced with other resources, notably gas-fired plants, from which energy output is dispatched or curtailed as needed to meet load requirements.

“The study confirms our intuition that solar can provide the most value to the system if grid operators fully utilize the flexible dispatch capabilities of solar power plants, especially under increased solar penetration levels,” E3 Senior Partner Arne Olson said in a news release announcing the study’s conclusions. “Utilities and grid operators should stop thinking of solar as a problem to be managed, and start thinking of it as an asset to be maximized.”

E3 used an energy model to simulate generator unit commitment and dispatch on Emera Inc. subsidiary Tampa Electric Co.’s system in Florida. TECO was an active participant in the study and provided data on its system, which has a generation portfolio that is 86% gas-fired.

Traditionally, control of solar output is not considered in generator scheduling and economic dispatch. However, many modern solar power plants have the technical capabilities to precisely control their output. Such plants, referred to as flexible or dispatchable solar, can be called upon by a grid operator to meet system requirements.

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