The “battery” will probably be a turbine running in reverse pumping water into a reservoir, or hot fluid from a solar-thermal plant being circulated through a salt bed capable of storing energy through phase change. Not a chemical battery.
Huge satellites orbiting so that several are always exposed to the sun, combined with a world-spanning power grid and microwave power transmission. Hell, even without the satellites, a worldwide grid based on very high voltage (hench, low loss) DC power would solve a lot of day-night problems.
