Community solar is hot, and customers have more opportunity than ever to participate in the solar revolution – whether or not their own roof can accommodate panels. Well-designed community shared solar (CSS) programs give utilities an opportunity to expand solar offerings to their customers in ways that add value to the grid.
The Community Solar Value Project (CSVP), which is cosponsored by the U.S. Department of Energy SunShot Initiative, aims to increase the scale, reach and value of utility-based CSS programs, in part, by integrating suitable companion measures such as demand response (DR) and storage into program designs. A recently released guide from CSVP, “Incorporating Demand Response Into Community Solar Programs,” aims to help utility community solar program managers to select appropriate companion measures for incorporation into their own programs.
With the increasing popularity of CSS programs, utilities are seeking new integration strategies that will allow their distribution grids to accommodate more solar projects. By approaching customers with a well-designed joint solar/DR offering, utility program designers can achieve higher grid value than with a solar-only (or DR-only) program. DR, which encompasses everything from controlled air conditioner cycling to electric storage water heaters, to various time-of-use rates, can help offset the variability introduced by distributed solar resources, and solar can serve as a popular component of customer engagement around the need for DR.
Although DR programs have been around for decades, most to date have been designed to help utilities manage peak demand. To serve as a viable complement to solar resources as well, care must be taken to select the correct DR technologies, program designs and target customer segments.
Working with utility partners including the Sacramento Municipal Utility District and PNM in Albuquerque, as well as with an advisory panel of six other utilities throughout the western U.S., the CSVP team has validated a three-step approach described in the program guide:
1. Identify and prioritize the solar variability issues to be addressed by DR. Although some utilities may still be primarily concerned with shaving peak (which may be slightly later, thanks to solar), others may face new issues with net system load shapes. For example, there is significant popular discussion of the challenge some utilities face (or will soon face) in meeting a steep ramp in net system load in the late afternoon and early evening as solar generation declines while residential loads increase. Increasing penetration of solar can also cause over-generation in some hours, as well as increased intra-hour variability on partially cloudy days.
2. Review the “catalog” of possible DR options. The guide provides an example list of DR categories with performance and cost attributes; each utility may have existing programs or R&D projects that can provide additional detail. The catalog of available measures may vary significantly from one utility to another, based on wholesale electricity cost and variation in the types of equipment and appliances most common in different regions of the country. For example, electric resistance water heaters are rare in California, but they are common in the Pacific Northwest and rural areas of the South and Upper Midwest. Central air conditioners with smart thermostats may have significantly larger DR value in the South and Southwest than in New England.
3. Score each DR option by suitability in addressing each variability issue. By combining the results of steps one and two, the program planner can identify the measure or measures with the greatest benefit for his or her program. Utility CSS program designers have reported that this approach simplifies the program design process while raising value for the grid and for customers in their programs.
Although the guide presents many more DR options, a simplified subset of sample results are shown in the figure below:
By showing utility CSS program managers how to select and offer DR options as part of their CSS programs, the guide offers utilities a sound technical and market strategy for raising the grid value of CSS projects. The grid services offered by a combined CSS/DR program are significantly more valuable than either component alone.
Demand response options represent only one potential enhancement to community solar programs. The positive reception for this simple approach to integrated program design has led the CSVP team to pursue similar approaches for other design options, such as the selection of storage measures to be incorporated into community solar programs.
One thing is certain: Community solar programs are growing rapidly in many states. Utilities that take advantage of this growth to provide CSS program options to customers will have a better position in the rapidly changing electricity marketplace.
John Powers is CEO at Extensible Energy, an energy consulting and analytics firm that is part of the Community Solar Value Project. The guide is available to utility and solar industry professionals at communitysolarvalueproject.com.