By the subject of trade, the power market comprises three elements, which function as complementary markets:

• active power market - the subject of trade is active power, delivered in specific volumes, at a specific price, time and supply point,
• technical market - the subject of trade are ancillary control services necessary to enable transmission of contracted power, as well as electricity generated by specific generation units, where generation is forced by the technical constraints of the power system and the necessity to secure the adequate system reliability and maintain the qualitative parameters of power at the grid nodes.
• financial market - the subject of trade are financial contracts concerning supply of electricity, with supply volumes and price specified, however, not directly concerning the physical supply of energy; besides, also derivatives fall under this market: it allows players to secure themselves against the risks involved in trade in electricity as a product.

The active power market in Poland is composed of the bilateral transactions segment, the exchange-based segment, and the balancing segment. The balancing market segment administrated by the PSE S.A. is used for covering balance-adjusting actions and settlements which are necessary to execute electricity sale contracts concluded on the first two segments.

The balancing market consolidates all the electricity market segments. It covers transactions concluded by the PSE S.A. in order to close the balance and adjust electricity generation to the technical constraints ensuring the reliable and secure operation of the power system.

Individual participants of different electricity market segments conclude independent transactions, which are then added up in the scale of whole Polish power system. This sum of transactions does not have to ensure the balance between the demand and the supply of electricity. It is the balancing market that executes this. Owing to the changeable nature of power demand, and, on the other hand, taking into account existing technical possibilities, the basic time interval of the balancing market mechanisms and tools has been set at the level of one hour.