A guy here in Oregon had the same idea, but without the architectural finesse: http://www.airplanehome.com/

What's to keep us from storing energy in a different form? Say, use excess solar-generated electricity to run a motor which lifts a heavy weight (converting it to potential energy, which can later be used to spin a turbine and generate more electricity)? This is the same process that a grandfather clock uses (and yes, I know that Neil Gaiman described it in Anathem); there's some mechanical overhead, but it's more sustainable than chemical batteries... For that matter, why not use excess solar electricity to separate hydrogen from water molecules, creating fuel?