The Problem WIth Solar, Wind

Chicago Business is reporting:

Chicago-area consumers are being asked to take it easy on the power grid tomorrow.

PJM Interconnection, the operator of the grid in all or parts of 13 states, including Northern Illinois, earlier today issued a call for consumers to take conservation steps during high-demand periods tomorrow, as the severe cold continues to put stress on power supplies.

And that's the problem with wind- and solar-generated electricity: it can't ramp up when extra electricity is needed.