National labs look at who’s planning best for solar

Source: David Ferris, E&E reporter • Posted: Thursday, September 22, 2016

For a utility, guessing how much solar power its customers will build is devilishly hard. Over time, it will have a snowballing effect on the power grid, but it is made up of many unknowns: who will build, and where, at what size and in what year.

A new report takes a look at the planning documents of 30 utilities around the country and compares the tools that they’re using to plan for distributed solar, as it’s known. Most of those power companies see rooftop solar as a problem, while a minority are beginning to view it as an agent that can solve problems.

The report, called “Planning for a Distributed Disruption,” was written by two Department of Energy labs, the National Renewable Energy Laboratory and the Lawrence Berkeley National Laboratory. It makes the case that utilities need to find the best tools available for estimating how much distributed solar will enter the grid, since it will have an ever-greater impact on two of a utility’s key missions: keeping reliability high and costs low.

The power companies that have planned with the most ardor and creativity are in New York, in New England, on the West Coast and in Hawaii, where solar adoption rates are highest and energy policies are friendliest to solar. But innovators can be found in regions not known for solar leadership, such as the Midwest and South.

Solar isn’t being taken up at the same rate everywhere: A few utilities project that rooftop solar will represent the equivalent of 5 percent or more of retail sales by 2020, while many more estimate it will be no more than 1 percent.

“Because of this staggered progress, organizations that are just beginning to address [distributed photovoltaics] can draw on innovative practices from organizations that already are incorporating DPV rigorously into their plans,” the authors wrote.

The report highlighted a technique called customer-adoption modeling. Unlike other models that don’t rely on hard numbers to make predictions, customer-adoption modeling arrives at its conclusions by combining data on historical installations of PV, the potential of solar at specific locations, economic factors and customer behavioral trends.

This technique has been adopted by a quarter of utilities surveyed in the study, particularly in the West, including PacifiCorp, Puget Sound Energy and Pacific Gas and Electric, as well as two regional planning agencies, the Northwest Power and Conservation Council and the Western Electricity Coordinating Council.

Another planning tool, called acquisition path analysis, crunches several different scenarios together and stakes them with “trigger events,” which signal to the utility that conditions have changed enough that it’s time for the power company to alter its plan.

PacifiCorp and Hawaiian Electric Co. Inc. use this approach.

The report looks at many other planning tools, such as the strategic location of rooftop solar installations where they would do the most good on the grid. That approach is in use at Dominion Resources Inc., Georgia Power and Duke Energy Indiana, among others.

A handful of utilities are beginning to look at the efficiencies that distributed solar can bring to the grid, such as erasing the losses that the grid incurs as it moves electrons across long distances and delaying the need to build new transmission and distribution infrastructure.

On the other hand, the report said, more rooftop solar can require costly upgrades to the distribution system.