Floor price
The lowest price per kWh you will sell at. Buyers bid above it; anything below it stays with you.
You set the floor once in the app. Every block, your surplus is listed at that price and buyers bid upward from there. If no bid reaches the floor, the block does not sell and your power goes to the utility as usual.
A good floor is a cent or two above what your utility pays for export. See how to pick one.