[gizmo686]

Two subtleties involved here:

A) There are actually 2 price ceilings. The $9000/MWh is the "high" cap. The situation lasted for long enough that they were supposed to switch to the "low" cap of (the greater of) $2,000/MWh or 50x the natural gas price index. Due to the also high price of natural gas during the crisis, this "low" cap ended up being higher then the "high" cap.

B) To protect the grid at a techincal level, portions of it were disconnected (load shedding). The result is that the "market" value within the grid that remained connected actually did drop below the cap. Since this only happened because supply was so low that some consumers couldn't buy at any price, the decision was made to set the price to the cap to better reflect the full demand instead of just the demand that was still connected.