Create Gas then
Both wind and solar are intermittent, usually producing power when it is not needed. I recall hearing an interview on the radio where it was suggested that the power produced could be used to create gas, this gas could then be absorbed by the national gas grid which has sufficient elasticity to accommodate this irregular . When power is needed then a gas power station is fired up. Simples!
I also agree with those respondents who suggest river power. My local river (The Wharf) has never run dry in all the years I've been here.