If your power gets cheaper because it's all renewables, then anyone could save up that money and use it for those situations.
But also, buying such a variable-price contract is only going to be an option. If you want a certain amount of guaranteed-price power, as an individual household, there will always be someone willing it to you.
But more realistically you'll be able to pay more per watt for that short period and get as many amps as your house can handle.