Solar power has begun to transform the world’s energy system

Transmission lines are a interesting idea, but expensive.

Once solar is cheap (like now, as it already is), you can put in 3x what is needed on a sunny day, and power everything on cloudy days. Solar runs on cloudy days. Night obviously requires a different solution. Start by installing solar over all parking lots.

To think that you won't be able to run a 100% solar/wind grid is a bet against human ingenuity. If generation in excess of peak demand was installed of solar/wind, there are many promising approaches to deal with generation shortfalls. Batteries, load shifting, an electric vehicle fleet that charges during the day and powers the grid at night if the owner opts in, precooling a home with AC during the day to a low set point so AC isn't needed at night, H2 storage in salt caverns, pumped hydro, aluminum smelters that operate during excess power periods, the possibilities are infinite.

It won't be hard. Don't bet against human ingenuity.

Solar over parking lots is so good. it creates power, shade, and reduces reflected heat.

Especially at workplaces or shopping malls, where most people park during the day, you can also install lots of EV chargers and use produced power onsite.

You are right. A different way of thinking of this is that we'll be able to saturate whatever cable capacity there is with excess solar and wind in order to charge whatever battery capacity needs charging. It's a careful balance between time shifting solar and wind with batteries or shifting it in space with cables. They complement each other. The natural consequence of people installing more solar, wind, and batteries than they need is running surpluses most of the time. Which means that whenever there's a local shortage, cables are a way out because there's plenty of energy in the system. The more excess energy there is, the more attractive cables get.

It's not an either or thing. And this will be a self optimizing system as well. It won't be up to grid operators anymore. If people need more power, they'll get some even if the grids won't provide it. And if they need it to be more reliable, they'll fix it anyway they can. Which includes using batteries, generators, and whatever else works.

Hydrogen for energy production is a bit of a fantasy IMHO. Awful battery. Expensive to create. And there are plenty more profitable uses for it than sacrificing it as a simple methane alternative. Honestly, burning it is a bit desperate. If you have all this valuable hydrogen and burning it is the most valuable thing you can imagine doing, you're doing it wrong and missing out on some big dollar amount of more sane shit you should be doing.

Cables are expensive mainly because of policy. They are mainly made using commodity materials (copper, aluminium, etc.). Cable manufacturing isn't expensive. Installing them isn't rocket science. Land disputes on the other hand are cripplingly expensive. Solve that and cables become cheap. Geothermal works the same way; not that hard. Drill some holes (oil companies are really good at this) and that's most of the work. Getting permission to do that is the hard and expensive part.

You missed a huge upcoming one: EV's. I firmly believe that paying EV owners with vehicle-to-load capability will soon be used to smooth out peaks and troughs in the grid. Maybe in the future even systems that use DC fast charging contacts to get the huge DC voltages needed for an external inverter capable of powering several houses.

As in, "an electric vehicle fleet that charges during the day and powers the grid at night if the owner opts in"?

And you can't make a parking lot any uglier.

I think this would work for the summer months. Overnight storage is manageble/cost-effective by load shifting/battery storage/etc. This is now estimated at about $100/MWh ($0.10/Kwh).

Seasonal storage is a completely different story. For my own panels, production in Nov/Dec/Jan is about 20% of that in Apr/May/Jun, and this is typical. That means that you either need 15x solar capacity of what you need on a sunny day, or enough storage to bridge those 3 months, two orders of magnitude storage more than we would need to store electricity overnight.

I think they were talking about homes not businesses

It's not going to be optional. And day/night isn't even nearly fine enough granularity. It'll be minute by minute and grid tied.

I suspect we'll see the grid get very close to 100% being the "base" load, and the complexities of having power flow in so many directions will cause the largest blackout to date.

Or some combination of the two. Obviously sounds expensive but 20 years ago this would have been fiction. I think it’s entirely likely that energy storage and production will continue to fall enough in price to make this realistic.

Once there are 50M electric cars parked here and there, the solution will be even more obvious.