Solar to help Texas meet this summer’s peak demand

In Texas and across many parts of the United States, summers are getting hotter. This means more air conditioning and thus more electricity use. Add to this an economic rebound, and Texas’ grid operator is predicting a 2.7% increase in peak electricity demand in the summer of 2018 over the previous record, set in August 2016.

Fortunately, the state is adding solar at a rapid pace, and this is expected to help keep the lights on and the AC running. Backed by a boom in large projects in West and North Texas, the state rose to become the 2nd-largest state solar market in the first nine months of 2017.

The latest report by the Electric Reliability Council of Texas (ERCOT) shows both these trends, and shows solar as the largest source of new generation expected to come online in the next few months to meet summer demand.

ERCOT’s Preliminary Seasonal Assessment of Resource Adequacy (SARA) for summer 2018 shows that its portion of the state has reached 1.1 GW of solar projects larger than 1 MW.

According to ERCOT’s calculations, solar does not meet peak capacity needs on a 1:1 basis, which is likely due to peak demand coming typically in the afternoon after solar generation slows. ERCOT rates solar at 75% for peak capacity, meaning that this 1.1 GW of solar will supply an estimated 829 MW of peak capacity.

Texas has a much larger wind fleet at over 20 GW, and despite the much lower contribution to meeting peak load, this resource is still expected to supply over 4 GW of peak capacity. And while turbines along the Gulf Coast represent only 13% of the state’s total wind, these make up 40% of the state’s wind’s peak capacity contribution, as “coastal” wind tends to produce more in the late afternoon and evening.

ERCOT is expecting another 387 MW of additional utility-scale solar to come online by summer, and given the higher peak capacity contribution this will be the largest contributor to meeting peak demand in the next four months.

The contributions of this solar, 660 MW of wind and 160 MW of gas turbines is not as great as the anticipated 1.9 GW increase in demand, which means that the grid’s reserve margin is shrinking. This is of particular concern in the event of low wind output.

ERCOT is still a long way from rolling blackouts, however the grid operator says that the tight supply situation could result in the need to deploy ancillary services, emergency response capacity and demand response.

It remains to be seen how long that will be a problem, as the ability of solar to meet Texas’ electric demand – peak and otherwise – is just beginning. In 2015 ERCOT predicted that the state would add 13 GW of solar by 2030, 50 times the amount it had online at the time, and in 2016 SEIA and GTM Research forecast that Texas would add 4.6 GW of solar over the coming five years, as the nation’s second-largest market.