There already is negative priced energy in some (most?) markets. In the UK there's a provider called Octopus that have a tariff called "Agile" that is based on

There already is negative priced energy in some (most?) markets. In the UK there's a provider called Octopus that have a tariff called "Agile" that is based on the 30 minute day ahead auctions - and it sometimes goes negative (you get paid to consume when there is an excess of generation).