Transmission and distribution deferment using PV and energy storage

It is often assumed that distribution-connected PV can help defer the need for distribution system upgrades, but there is not a general approach for assessing the deferment value of distribution-connected PV and distribution-connected PV combined with a storage system (e.g., battery). A vital component of such an analysis is time-coincident load and solar resource data, since load (especially peak load) is usually correlated with solar resource and temperature conditions, and both factors determine PV system performance as well. This paper demonstrates a methodology to analyze the value of using PV to defer distribution system upgrades. The paper also assesses the additional benefit of combining energy storage with PV to increase this deferment value. The case study involves replacement of a station transformer.