The curtailment paradox in the transition to high solar power systems

Rising penetrations of variable renewable energy (VRE) in power systems are expected to increase the curtailment of these resources because of oversupply and operational constraints. We evaluate the effect on curtailment from various flexibility approaches, including storage, thermal generator flexibility, operating reserve eligibility rules, transmission constraints, and temporal resolution, by using a highly resolved realistic system. Results reveal two aspects of a curtailment paradox as the system evolves to higher solar penetration levels. First, thermal generator parameters, especially in restricting minimum operating levels and ramp rates, affect VRE curtailment more in mid-PV penetration levels (similar to 25%-40%) but much less at lower (similar to 20%) or higher (similar to 45%) PV penetration levels. Second, although allowing VRE and storage to provide operating reserve results in significant operating costs and curtailment benefits, the price suppression effect from these resources reduces incentives for PV to provide operating reserves with curtailed energy.

Automated summary

As solar penetration levels increase, flexibility approaches can reduce curtailment, but the impact factors vary at different stages, and allowing renewable energy and storage to provide operating reserves can bring both costs and benefits, but also reduce incentives for solar to provide operating reserves.