How would you dump it at this large scale? The point of “selling” it at negative price is to encourage consumers to connect loads on the grid in order to burn this extra energy to maintain grid balance.
As a Finn, probably just send out a message on some social media platform that people need to start turning on their saunas for the stability of the network. (Alternatively, like fingrid did, send a notification to my phone saying to "consume energy normally, as the pricing issue does not reflect energy availability")
Even a fairly small electric sauna is ~10 kW, so that's be just 10000 homes solving that problem.
Very few people get paid during this market anomaly. Most people have fixed rate contracts, and the few that do have variable rates, even fewer have ones where the negative price would be passed on to you.
Transmission cost and taxes will still be present, so this is more of a "hey it's going to be a societally good thing to go to the sauna today instead of tomorrow, consider it!" (Also, the saunas are definitely in use, don't worry, nobody's going to pass up the opportunity to say they went to the sauna for a good cause.)
Or, via lower price - negative if necessary - you let someone else go to the trouble, via facilities that they themselves invested in. Also in systems like this, there is not necessarily anything special about "zero" or "negative". It's just "less than the previous number" or "more incentive this way than the previous number".
The idea that negative prices are something weird is pretty silly.
A negative price indicates that the person sellers disposal technique is worse than the buyers disposal technique. In other words, the market is working as intended.
Nobody is complaining about the cost of garbage disposal where people are paying for having less (!) stuff.
