On the transmission side, every year in March, the Portuguese TSO publishes a report on the generation and transmission system of the previous year, which includes the generation portfolio, the contribution of the different generation technologies to demand, interconnection exchanges, main network developments, network composition, network losses, and other information.  

This report also includes, by transmission substation or groups of substations, the firm capacity (capacity available all the time, except in rare exceptional situations) available for the connection of new generation. Because new generation in different substations can contribute to the same network constraints, capacity is published by geographical areas/substations rather than by individual substations. 

The Portuguese TYNDP also presents new network firm capacity that will be available with new network reinforcements presented in the plan. This additional capacity only takes effect after approval of those specific reinforcements and putting them into service. 

It should be noted that in some cases, power plants may be unable to produce not due to network constraints, but because of market conditions, such as excess generation compared to demand. 

At the DSO level, E-REDES, as the main operator of the electricity distribution network in mainland Portugal for HV, MV, and LV networks, publishes information in both table and map format.