They're getting so cheap because they produce energy at times we don't need it, so market price fall through the ground to zero or even negative flash prices. Low prices are an compound artefact of heavy subsidizing and production in complete inadequacy with demand.
Electricity storage doesn't exist. There is no existing industrial solution at scale (except hydro, but there's no room left for expansion in Europe). We're talking of scales of many GWh of storage. Then there's price of a multi-GWh storage.
Our society is entirely relying on on-demand power generation. Wind and solar are utterly inadequate tools. In actuality while Spain installed 20GW of wind and solar, it also installed 15 GW of gas-powered plants. Climate change anyone?