Germany had so much renewable energy it had to pay people to use electricity

Price dips (or spikes) such as this are better understood as forecast failures: inability to accurately predict available renewables supply relative to demand, and/or not being able to cut back thermal (fossil) generation rapidly enough (coal and nuclear plants respond slowly).

The headlines are impressive, but these really aren't the events you want to watch, but rather the long-term average renewables contribution and absence of either negative or very high price anomolies.