Negative energy prices are a relatively new phenomenon, and it attracts attention because of its counterintuitive nature (I can get paid to use electricity?!?). Yet, it doesn’t happen that often. If I look at the Dutch market, this mostly happens on sunny+windy Sundays.
I think 2 things are happening that will make arbitrage feasible:
1. As solar production capacity increases, so will opportunities for arbitrage
2. As battery costs keep going down (capacity learning curve), so will the investment to do arbitrage.
At some point the curves for (1) and (2) will cross convincingly enough that investing in storage is just good business, and people will invest. If it’s anything like solar (home batteries), adoption might actually go very quickly because decision making would be decentralized, small investments, and without permits.