Because batteries are expensive but needed for overnight storage or cloudy conditions. There’s also the amount of land and materials needed to produce solar devices.

It’s ultimately more about unit cost of power than total available power.

Can we not build solar panels in the ocean like we do with wind turbines?

"Because batteries are expensive"

Are they? It would only take 4000 copies of the Moss Landing Energy Storage Facility to store all the electricity we currently use in a day.

Some back of the napkin math says it would cost $2 Trillion, which is only double the amout we subsidized the fuel industry last year

> Can we not build solar panels in the ocean like we do with wind turbines?

Technically yes, but that's a bad idea: ocean environment is very unforgiving, and has more clouds than land has. It also has more (and more reliable) wind and fewer people complaining about the very large turbines, which is why it works for wind.

> Some back of the napkin math says it would cost $2 Trillion, which is only double the amout we subsidized the fuel industry last year

Napkin maths also says that a global power grid would be 10% of that price. By coincidence, it takes a cross section of almost exactly 1m^2 to make a 40,000 km long line have a resistance of 1 Ω.

Further investigation said that literally only China has that much spare capacity for aluminium production, but still.

That kind of scale of battery production is still needed for the cars, though.

Because that inefficiency directly impacts whether or not, and how fast, it makes sense to pursue tapping into this source, especially that there's a limit to the build up rate we can sustain, and because there are alternative sources to pursue in parallel, that are better along these dimensions.