By the mid-2010s, distribution utilities in many regions began the process of changing planning and design processes to account for increasing amounts of distributed energy resources (DERs) including rooftop solar and other distributed generation, advanced demand side management capabilities, and distributed storage. Integration of significant amounts of DERs may require circuit redesign to account for injections of supply on distribution circuits and, in some cases, even reverse flow of power from the distribution circuit back into the distribution substation. Areas requiring redesign include equipment for voltage and VAR management as well as protection schemes. In some cases DERs can be managed so that line upgrades can be deferred or provide other benefits such as VAR management. In other cases, growth of DERs requires line upgrades.
Some distribution utilities are moving toward a planning process that replicates the integrated resource planning process used for central generation and transmission. A distribution resource plan (DRP) is developed by a distribution utility to optimize integration of DERs and identify how and where DERs can be used as economic grid resources. Key components of a DRP include:
- Forecasts for growth of DERs
- Identification of impacts of DERs on the grid overall as well as on specific circuits
- Development of plans for grid modernization necessary to effectively integrate DERs
- Analysis of the locational value of DERs and identification of circuits where DERs can provide effective non-wires alternatives
- A final plan outlining how the utility will implement steps to integrate DERs and utilize them as grid resources
Development of a DRP includes six steps: