Texas and California urged consumers to conserve energy this week to reduce stress on the grid and avoid outages as homes and businesses crank up air conditioners to escape a scorching heatwave blanketing the U.S. Southwest. High temperatures were expected to top 110 degrees Fahrenheit (43 Celsius) through the weekend in parts of several states including California, Arizona, and Nevada. “The public’s help is essential when extreme weather or other factors beyond our control put undue stress on the electric grid,” said Elliot Mainzer, chief executive of the California ISO, which operates the grid in most of California. Over the past year, Texas and California imposed rotating or controlled outages to prevent more widespread collapses of their power systems—California during a heatwave in August 2020 and Texas during a brutal freeze in February 2021. The Electric Reliability Council of Texas (ERCOT), the state’s grid operator, expects Thursday’s demand to break …