Hydrogen. However electrolysis is still an immature technology and has massive energy losses in every step of the procedure. You can negate that somewhat if produce and store at the same location of the intended use, like providing electricity to a building with hydrogen tank, hydrogen that is generated by solar panels.

However this is of course not enough to run industries with high electricity demand, what people tend to forget is that one factory (like melting of aluminum) can consume more electricity in one day than an entire city in a year. For that you need nuclear power or hydro.