When the supply of or demand for electricity is greater than the electricity network in a particular region can handle (congestion), the grid operator issues a market message calling on the market (such as energy suppliers, CSPs, and large consumers) to place bids to use or generate more or less electricity compared to previously planned production or consumption. If these companies can temporarily reduce (or increase, depending on the grid operator's request) their consumption or production of electricity, they then indicate how much flexible capacity they have available and at what price they are willing to sell it. We call this a flexibility bid.
