Basically, hydroelectric power is a gravity battery. What they're talking about is using an electric motor to hoist a heavy weight while the sun shines later reversing the process to generate power. Like an ugly windmill, you can expect money laundering of taxpayer funds to build big ugly towers that will fail soon after the taxpayer subsidies end. Yea, it will be great!

If you hang a magnet, as a pendulum, over another magnet with an opposing field, gravity will keep it moving forever. Build to scale and add wind, and you've practically got perpetual motion.