Hence the Pacific DC intertie:
https://en.wikipedia.org/wiki/Pacific_DC_Intertie
"The Pacific Intertie takes advantage of differing power demand patterns between the northwestern and southwestern US. During winter, the northern region operates electrical heating devices while the southern portion uses relatively little electricity. In summer, the north uses little electricity while the south reaches peak demand due to air conditioning usage. Any time the Intertie demand lessens, the excess is distributed elsewhere on the western power grid (states west of the Great Plains, including Colorado and New Mexico).[3]"
(that predates solar, boy do I wish we could store that daylight 12-16 hours)