Solar Curtailment Could Rise Globally as PV Penetration Increases

The trend of curtailment of renewable power has started taking shape globally. Power firms in China, Chile, several U.S. markets, including Arizona, California, Hawaii, and Texas, had to curtail at least 1% of their potential solar generation in 2018, according to a recent report by National Renewable Energy Laboratory (NREL) researchers.

In the global market, curtailments were driven by the location of the projects, transmission limits, and oversupply. Reduction in solar absorption also followed seasonal patterns and was influenced by policy and grid planning.

The study on global markets predicts that solar power curtailment is likely to increase in these and other markets around the world as solar power capacity rises.

In India, Central Electricity Authority (CEA) discovered that thermal power projects might be able to scale down their capacity generation to a minimum of 40%, beyond which running the project would not be techno-economically feasible.

CEA, the power advisory arm of the Indian government, predicts that up to 14.6% of domestic renewable power may be curtailed on certain days, in a report that estimates optimal generation capacity mix until 2029-30.

CEA Estimated Power Generation Mix in India

The reasons could be a mismatch in power demand and renewable generation during a day, the ability of thermal power projects to scale down production, gas availability, and minimum power flow necessary for hydro projects.

Solar power curtailment has been mired in controversy in Karnataka, Telangana, Punjab, and Andhra Pradesh. Solar developers in these states have already sought state regulatory commissions and court intervention. Solar developers have sought transparency in grid curtailment issues.

Globally, in terms of geographical constraints, limited transmission capacity between solar-heavy regions and load centers are crucial drivers in reducing solar power injection into the grid in areas such as Chile, China, and Texas.

In each case, grid planners have responded with initiatives to increase transmission capacity connecting solar resources to load centers.

“Grid flexibility, storage, demand response, and regional coordination could reduce losses. Optimal rather than minimal curtailment is more efficient for future grid contexts,” the global study indicated.

Increasing grid flexibility and technological advances such as low-cost battery storage could avoid future curtailments.

According to CEA, installed capacity by the end of 2029-30 is projected at 817 GW. It is expected to include 40% non-fossil fuel power generation capacity by 2030.

Projected gross electricity generation during the year is likely to be 2,518 billion units in which non-fossil fuel generation would occupy 44.7%.

Curtailment is generally considered to be an opportunity lost, and various grid and market customs discourage stepping down solar generation. However, changing grid technological contexts are forcing a re-examination of solar generation curtailment and its stigma.

As grids see higher levels of solar generation, it becomes more efficient to emphasize an optimal rather than a minimal solar power generation restrictions.

“A shift in thinking toward curtailment management rather than prevention could increase the value of delivered and curtailed solar power output to the grid. Various grid flexibility measures—including flexible generation, storage, load flexibility, and regional coordination—could be key components of a curtailment management scheme,” opines the global study.