Wind can put electricity on the market even without subsidies. They have every incentive to do so, since it costs them absolutely nothing to put energy into the grid while forcing fossil fuels to pay a premium.
If the government didn't subsidize renewables when the grid is oversupplied, then other resources would pay them anyway. Prices would even go negative as transients would still exist. Since the subsidies are far less than the premium made by fossil peaker plants, renewable resources are still the first to turn off and the time difference is negligible.
Not to mention that in most countries the subsidies are by FAR the least distorting legislation. Most often (eg the US) renewables get first bid on contracts. That means they are guaranteed to sell their electricity even if the price goes negative; the onus is on fossil plants to turn off. This is a dumb, possibly unnecessary bit of rule. It ensures renewables are used, but it means they aren't well utilized as peaker resources. Renewables are orders of magnitude better for the grid than any other type of generation, but if they wanted they would never be used for anything but baseload.
If the government didn't subsidize renewables when the grid is oversupplied, then other resources would pay them anyway. Prices would even go negative as transients would still exist. Since the subsidies are far less than the premium made by fossil peaker plants, renewable resources are still the first to turn off and the time difference is negligible.
Not to mention that in most countries the subsidies are by FAR the least distorting legislation. Most often (eg the US) renewables get first bid on contracts. That means they are guaranteed to sell their electricity even if the price goes negative; the onus is on fossil plants to turn off. This is a dumb, possibly unnecessary bit of rule. It ensures renewables are used, but it means they aren't well utilized as peaker resources. Renewables are orders of magnitude better for the grid than any other type of generation, but if they wanted they would never be used for anything but baseload.