People seem to think "the grid" is like an enormous water bucket you can simply dump electricity in whenever, then extract as needed.
That's a battery. The grid isn't a battery. But EVs do this job perfectly, if only they were allowed to.
then when the sun's shining, then that surplus has no value at all. Worse, it actually becomes an expensive problem for the grid to manage -- it literally costs them money to dispose of it.
Why would anyone with solar export surplus if the grid (I.e. neighbors/businesses) doesn't need it at the time it's being generated? The inverter itself throttles its production, or a smart meter easily does that job also. You only export surplus if and when there's a demand for it, otherwise it's pointless. This isn't a situation where you 'have to' export anything for profit. Most of my 100kWh daily solar production doesn't even get generated each day since I don't have enough loads for it beyond, say, 30kWh. That doesn't mean I 'have to' still produce the 70kWh excess, and then go and try to sell it, because nobody would need it at those hours, except maybe a little for businesses and factories that are usually the main energy users during the day.
They can make electricity free and fair for everyone, by balancing out import/export amounts for the 16hr nighttime period. For example, those with an EV who export at night, get paid X amount per kWh, and then can buy back up to X amount say tomorrow night if their EV is unavailable that night, making their import/export ratio nil (I.e. free). And the grid will be in charge of 'funneling' this electricity as and when needed/generated, second-by-second. The grid doesn't need to make anything themselves at all. If there's too much nighttime generation versus demand, the meters will auto throttle exports to match demand exactly.
People without an EV or battery will have to buy their nighttime electricity, until they get one to start exporting. Whereas, people with one, will be able to sell their nighttime electricity for a decent profit, until everyone gets onboard, then buys/profits will level out for the most part, and electricity will just be free all around, because nearly everyone will essentially be making/using their own electricity, except for the outliers like ones who use their EV at night for example.