New report develops simple methods to explore the resource adequacy contribution of solar and storage

October 29, 2019

We are pleased to announce the publication of a new report titled “Drivers of the Resource Adequacy Contribution of Solar and Storage for Florida Municipal Utilities.” This report describes relatively simple methods for estimating the resource adequacy contribution of solar and storage. Simple methods can be useful for many utilities and regions addressing similar questions prior to evaluation of specific cases that require more detailed and resource-intensive modeling.

Energy storage is a leading option to increase solar’s resource adequacy contribution, yet the contribution from different configurations of solar and storage is not widely understood. We develop relatively simple methods for estimating the resource adequacy contribution of solar and storage, and we apply the methods to a case study in Florida, where demand peaks in winter and summer.

We find that the portion of solar nameplate capacity that contributes to resource adequacy—its capacity credit—is less than 50% and that it declines with increasing solar penetration.

The capacity credit of storage, even though it is fully controllable by the system operator, strongly depends on the duration of storage. The capacity credit of 1 hour of storage can be less than the capacity credit of solar. Achieving a 90% capacity credit requires at least 4–5 hours of storage when storage capacity is small relative to the system peak. As storage deployment increases to 20% of the peak demand, 9 hours—and sometimes more than 10 hours—of storage are needed to achieve a 90% capacity credit. Increased solar deployment at the system level can increase storage’s capacity credit. 

Directly pairing solar and storage can also impact the capacity credit. We find the capacity credit of a solar and storage coupled system can be less than the capacity credit of an independent system if the storage size is similar to the inverter size. This is because the inverter limits the ability of solar and storage to simultaneously produce power at the time of peaks.  On the other hand, there is no reduction in capacity credit when the storage is small relative to the solar inverter. 

The Lawrence Berkeley National Laboratory report on the resource adequacy contribution of solar and storage can be found here. The research was conducted as part of an award called the Florida Alliance for Accelerating Solar and Storage Technology Readiness funded by the Solar Energy Technologies Office of the U.S. Department of Energy.

 

 

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