"Without a cheap, reliable storage medium, solar is useless or extremely expensive. All the more so at power plant scale." Really? Why is it more so at power

"Without a cheap, reliable storage medium, solar is useless or extremely expensive. All the more so at power plant scale." Really? Why is it more so at power plant scale? When you're connected to the grid you have the benefit of being attached to more users, which seems like it'd increase the probability that someone somewhere could use the power. Lots of power plants - e.g. anything fossil fuel based can simply burn less fuel - can reduce their output fairly simply, so until they all bottom out it seems you wouldn't have a problem getting the energy to someone who wants it. Where this starts to fall apart is transmission losses; there is benefit to having the consumers and producers be closer together, in terms of resistance. It's possible that high-Tc superconductors may help in this space in the coming decades.