US CURTAILMENT TRACKER: CAISO curtailments jump 283% in February, load eases

Wind and solar generation curtailments in February climbed over 200% month on month, for the second month in a row, even while renewable capacity and battery storage capacity was unchanged, as load eased in the shoulder season, according to California Independent System Operator data.

CAISO's renewable curtailments reached 203.969 GWh in February, a jump of 283.4% month on month, but a decrease of 22.2% year over year, according to CAISO data, seen March 29.

Curtailments typically increase going into spring as longer days provide more solar generation and seasonal weather changes increase wind speeds and wind generation.

California hydro production will be very strong in the second quarter, said Morris Greenberg, senior manager of North American power analytics with S&P Global Commodity Insights, adding he expects this will drive high system curtailments.

Months of winter storms have brought significant precipitation to the West, building up hydro supplies after years of drought conditions.

Curtailment breakdown

S&P Global's systemwide renewable generation curtailment index showed CAISO wind and solar curtailments averaged 1,085.4 MW in January, a jump of 224% from January, but a decrease of 19% year on year.

There are two types of curtailments. Systemwide curtailments occur when there is an oversupply, and localized curtailments occur when the amount of power from one transmission point to another is controlled for congestion management.

Localized curtailments made up 90.75% of all renewable curtailments in February, down nearly 3 percentage points from a year ago, according to CAISO data. Systemwide curtailments reached a seven-month high of 9.3% in February.

As renewable curtailments climbed month on month, spot power prices dropped. SP15 on-peak day-ahead locational marginal price decreased 52% to average $66.15/MWh in February, according to CAISO data.

Renewable capacity

CAISO's installed renewable capacity remained at 27.51 GW through the end of February, unchanged for a third month, but up 4.7 from a year ago, with solar accounting for 59.7% and wind making up 28.9%, according to CAISO's February Key Statistics report. The remainder came from geothermal, small hydro and biofuels.

Solar-powered generation averaged 9.3% of the total market share in February, little changed from a year ago, while wind-powered generation averaged 7.6% of the mix, up 1.1 percentage points year on year, according to CAISO data. At the same time, CAISO peakload decreased 2.2% month on month to average 26.836 GW in February.

As renewable capacity has risen, so have battery installations. CAISO's installed battery capacity was unchanged month on month at 4.515 GW by the end of February, a jump of 93% from a year ago, according to CAISO's February Key Statistics report.

Outlook

So far this month, curtailments have totaled 518.362 GWh through March 27, an increase of 24% from the same period a year ago, CAISO data showed.

In power forwards, SP15 on-peak March averaged $48.97/MWh in its last month, 22% lower than where the 2022 package average a year ago, according to S&P Global data.

The month-to-date SP15 on-peak day-ahead LMP has averaged nearly $63.50/MWh, an increase of 64.6% from the March 2022 average, according to CAISO data.

The six- to 10-day outlook indicates a greater probability for below-normal temperatures across California with above-normal precipitation, according to the US National Weather Service's Climate Prediction Center.