The Regulatory Assistance Project (RAP), a clean energy independent think tank based in Montpellier, Vermont, developed a framework for electric utilities facing a significant solar integration challenge known as the “Duck Curve”. This framework is describe is further detailed in the report “Teaching the Duck to fly”.
The “Duck Curve”, this metaphor of the shape of a duck illustrates the change in the hourly electricity demand curve introduced by solar energy every morning when the sun starts to shine and when the sun sets in the evening. This change in net load profile, exacerbated every year by more solar generation, impacts the power system operators in charge of dispatching centralized generation on a minute-by- minute basis. The Figure 1, from the above-mentioned report depicts the Duck Curve phenomenon in California.
In their report, the RAP proposes an integrated approach to power system planning, describing 10 strategies that would steadily “re-shape” the demand curve and introduce power system flexibility. Here’s a summary of the 10 strategies:
Strategy 1. Target energy efficiency to the hours when load ramps up sharply;
Strategy 2. Acquire and deploy peak-oriented renewable resources;
Strategy 3. Manage water and wastewater pumping loads;
Strategy 4. Control electric water heaters to reduce peak demand and increase load at strategic hours;
Strategy 5. Convert commercial air conditioning to ice storage or chilled-water storage;
Strategy 6. Rate design: focus utility prices on the “ramping hours” to enable price-induced changes in
Strategy 7. Deploy electrical energy storage in targeted locations;
Strategy 8. Implement aggressive demand-response programs;
Strategy 9. Use inter-regional power exchanges to take advantage of diversity in loads and resources;
Strategy 10. Withdraw inflexible generating plants with high off-peak must-run requirements.
Among those ten strategies, six of them rely on distributed energy resources (DER) or demand-side technologies, one on rate design and the two others on interconnection and generation flexibility.
Coming from a group called “Regulatory Assistance Project”, also versed in the regulation aspects, this report not only provides good planning guidance, but it also makes the case for an extended role utilities could play in planning new energy resources. While it seems clear that distributed energy resources will re-shape the demand curve, it could very much re-shape entire utility departments as well.
Embracing DER solutions impacts the core asset management strategy of utilities and force power system planners to find solution “beyond the meter”. For decades, utilities invested on grid assets, mastered the techniques to keep the lights on at a relatively low cost and with none or very little information. With a slow demand growth and a limited distributed generation, power system planners were “on top” dealing with a few investment justifications, new connections request and maintenance problems a year. My former colleague in distribution planning told me “Listen, if we shut down this department, nobody will notice within the next 3 years, when capacity and voltage problems start to arise.”
This was in 2002, now in 2017 the solar wake-up call is real for many utilities who must integrate thousands of new solar installations per year, even facing an almost instantaneous 6,000 MW power drop during the expected August 2017 solar eclipse.
Solar energy integration comes with a lot of challenges (revenue losses, overloads and voltage problems), but solutions to mitigate its impact exist. A good starting point is to forecast solar adoption on each feeder individually by taking into consideration the very own characteristic of the distribution network, of solar radiance and customers.
While helping solve potential problem and preparing grid investments, this process also helps identify new products and services that may be offered to customers connected to a feeder. This could turn a problem (solar) into opportunities for technology or energy services.