A major challenge for producers of electricity from solar panels and wind turbines is akin to capturing lightning in a bottle. Both solar and wind increasingly generate electricity amid little demand, when market prices are too low to cover costs. At noon on sunny days, for example, wholesale power prices in areas with high quantities of solar and wind occasionally fall below zero.
source https://www.lifetechnology.com/blogs/life-technology-technology-news/reversible-fuel-cells-can-support-grid-economically-study-finds