Batteries would be great but they are not necessary unless you want to replace all generation with solar which would be a gargantuan undertaking. As part of the current generation stack, even at expanded scale, solar works very well without storage.
Yup. There's no reason why we can't rely on peaker plants a little bit longer. In general, there's a ton of power-plants designed to turn on and off throughout the day to inject power into the grid when demand grows.
The chief benefit however, is that this happened starting at daytime hours (when workers come into factories and tons of energy is suddenly demanded from the grid). However, because 12:00 noon is peak solar, peaker-plants will shift to later in the day to 3:00pm to 5:00pm or so (as opposed to running from 12:00 to 7:00 each day, they'll maybe run 3:00 to 7:00 each day).
Peaker Plants can be Hydro or Natural Gas. Natural Gas Peaker Plants are the most expensive, and they currently happen to run during a similar timeframe as solar.
For now, Peaker Plants can remain the solution. We need something to work on cloudy / rainy days after all. And "battery" tech is getting better.
>We need something to work on cloudy / rainy days after all.
Even without storage, interconnecting grids with HVDC across the US (or across a continent) solves this problem really really nicely. China is already building tons of HVDC to do this, and we need to as well. Long haul transport over HVDC is also cheaper than peaker plants.
That said, natural gas peaker plants stick around as long as the fuel costs are low, and the capital has already been sunk into the plant. But for new capacity, I think there's going to be a huge shift towards storage.
You can also just change the definition of off-peak electricity.
The coal grid already provides cheaper electricity at different times of day, because it's not efficient to turn coal plants on and off. Right now that cheaper electricity is at night, because most electricity consumers consume during the daylight hours. So if you need a boatload of electricity and aren't too sensitive about the time, you can shift you consumption to the off-peak hours and save some money.
But if you're not time-sensitive in your consumption, you can shift to the sunny daylight hours, when solar power is available. And if you're really not time-sensitive in your consumption, you can even shift consumption from cloudy days to sunny days.
100% solar isn't the only scenario where a battery in the home would be useful. Even today, one could install a battery with an intelligent monitor that charges during non-peak hours and discharges during peak hours, effectively arbitraging the price of power. I have no clue if this actually makes sense economically, however.
