Balancing a load is not the same as storing surplus load. Batteries are easier and more efficient but they are wildly expensive at scale and don't store power as long.

Personally I think pumped hydro is king in this field but that's not to say hydrogen can't exist at the same time. Airplanes can't use either for power and they can't be line fed but they can use hydrogen. The biggest drawback to green hydrogen storage is how inefficient it is and that's why I say using solar you have to use anyway makes it more viable.