Nobody has ever made solar power at night yet, nor wind power when she's in irons. So using these renewable power rigs means having to store some of the energy somehow for low-production times.
We can store energy in many ways. To use renewable energy sources, whose supply is intermittent compared to our demand, we need to store energy at times of peak production for use when demand is high. To explore the ways we can store energy, read on...

Liquid-cooled nickel metal hydride (NiMH) batteries have relatively good power and energy.
Photo credit: Warren Gretz, NREL Staff Photographer