The operators of the many GW of floating PV in use seem to have solved your string problem, assuming there was any. My guess, not. Any competent engineer can d

The operators of the many GW of floating PV in use seem to have solved your string problem, assuming there was any. My guess, not. Any competent engineer can design a perfectly workable utility-scale energy storage system. All that is uncertain is which designs will be cheapest, or otherwise most practical. (There are many kinds of cost.) Experience will identify the best. We have lots of pumped hydro storage because we have lots of hydro generation easily retrofitted with a pump. Other utility storage is not being built out much yet because it would be stupid to build storage there is not renewable generation to charge from, and utility operators are not generally stupid. Small battery arrays that shift just a small excess of energy from midday to early evening, and otherwise stabilize grid fluctuations, have been massively successful.