For another, there's the issue of demand. Demand is different from total power needed in a day. Demand is how much power is needed at any given moment. As an analogy, think of a water faucet letting water flow out of a large basin. How open the water faucet can go (how fast the water can flow) is like demand in power. How much water is in the basin is like how much total power comes from solar panels and/or batteries in a day.
There's a yuge demand in the afternoons when everyone gets home from work and school at the same time. In the south (including southwest like Arizona) that means that offices are still running their A/C for the people who are still there, while many homes are also running their A/C to cool down as people come home. While the parents run appliances to do household chores they couldn't do while at work, etc. My solar inverters can provide 18kW of continuous AC power from my solar panels and/or batteries, which is almost always all I need for what my wife and I are running -- but she's retired and I work from home a lot. In other words, we don't usually run all of our appliances at the same time to do all of our chores in a brief period. And the AC (variable speed heat pump) rarely runs full blast because it's never really off (letting the house get warm in the summer) and having to rush to cool the house down by the time we get home (because we're always home).
Most people's homes don't operate like that, so my inverters wouldn't be able to all of a sudden provide all of the power they need every afternoon. And that's just the homes. With businesses and hospitals and such the demand is often too out of the park for solar inverters to keep up with.
Nope. The only way solar is practical is with decentralized solar like I have --- and even then it's practical only if all the variables are right for your situation and also if there's a dependable grid available for the times I don't have enough solar and battery storage.
Those are good points, some of which can be mitigated with smart technology. For air conditioning homes, kick them on at timed intervals (or just traditional thermostat settings for times when nobody is home so the house doesn’t get extremely hot).
Agreed completely that the grid demand is very high between 4pm and 9pm. When you start adding electric cars to the mix, demand will soar (though that too should be done with smart tech so it doesn’t have to kick on until later in the evening - but it will still increase demand at times when no solar is being generated).
Decentralized is absolutely the way to go, but not the way TPTB have centrally planned it. It is less stupidity than corruption I fear. It makes perfect sense to put solar panels on buildings - as many as possible - to power individual homes and feed the neighborhood too as possible. To go out and law panels on 25 sq miles of empty desert is about as absurd as possible a method to use solar when it can be generated, delivered and stored directly to the places of demand. All you need is surface area and homes and industrial buildings have plenty of that.
High use places (hospitals, factories, office towers etc) would need even more creative solutions. And just throwing the switch from coal/gas to electric on X date in the future will work about as well as switching water sources on X date did for Flint Michigan.