Solar and wind are intermittent
In Short
Solar and wind are as noncompetitive as they are intermittent.
A Few Details
Solar and wind alone can’t quickly replace all coal power plants, due to their main downside: intermittency, i.e., when the sun doesn’t shine or the wind doesn’t blow.
Compensating for such downtimes can only be achieved with:
-batteries and other solutions to store electricity such as pumped hydro-storage or hydrogen production;
-supergrid expanding the distribution of renewable energy from the US windy Midwest to night-time in the Northeast.
More Info