The marginal price of any good is the cost to produce one additional unit of that good. That applies to electricity too.

Saying "the highest cost available at any moment sets the price for everyone" is misleading, it's also the lowest marginal price required to satisfy the total load required to supply the market.

i meant that in the EU wholesale market , everyone gets the marginal price. It is not the cost of an additional unit, a mwh of renewables is practically free (if paid-as-bid) but gets paid as natgas (because it gets paid-as-cleared)

Yeah but that's how the market pricing works, it's a function of the auction process. Everyone pays the price required to satisfy the demand. See stock opening and closing auctions for a similar process. It feels odd that sellers get the higher price but it makes sense ultimately.

The margin price in that market is the marginal cost of a GW hour by for the last GW that satisfies the load required (demand).

this doesn't change anything. If supply was higher, e.g. using solar/wind/nuclear/coal, prices would be lower

that would work only if non-gas sources generated enough so that gas is not needed at all. As it is right now, solar producers are getting a bonanza in profits because they are being paid at exorbitant prices. At this level, they have no incentive to ramp up production to remove gas from the equation.

There's no single "they" for "solar producers". No matter what the existing producers do, even if they would all illegally collude, the current prices make it attractive for individual households to install solar panels and thus add new solar capacity.

> At this level, they have no incentive to ramp up production

In a monopoly situation, yes. Luckily there is competition, and at this level their competition has a great incentive to ramp up capacity. Which, frankly, is going to make them ramp up production so they can capture a bigger piece of the market when the situation isn't quite as ridiculous as it is today anymore.

If I'm making $10 a day from my solar panel, so after 30 days I'll make $300. Job done.

It instead makes sense for me to buy a new second panel for $100 after 10 days and then I can make $20 a day, then 5 days later buy a 3rd.

30 days into this I'll have made $45, and be making $30 a day instead of $10.