The specific issue identified by the parent would not be helped by batteries. Like solar panels, batteries output DC voltage, and have no inertia on the AC side

The specific issue identified by the parent would not be helped by batteries. Like solar panels, batteries output DC voltage, and have no inertia on the AC side. The solution in either case is the same. Put enough smarts in the inverter for it to have "synthetic inertia". If we didn't have the ability to do something like that in inverters, the solution would be something like flywheels to augment the chemical batteries.