Procedure
The law does not specify a procedure to be followed by the plant operators. When connecting a new plant to the grid, the grid operator is obliged to upgrade the grid if such an update is necessary for technical reasons to ensure security of supply and the grid's functioning. The costs of such an upgrade have to be borne by the plant operator/developer in question. Therefore, the plant operator/developer and the grid operator have to liaise on this matter.
Tasks of the DSO/TSO
The DSO is mandated to develop the electricity grid within its service area to ensure reliable service for all consumers, energy communities, and producers while meeting their justified needs. Development and use of flexibility services in a network must be based on a transparent ten-year plan for network development, which the network operator formulates at least every two years, according to the Electricity Market Act.
According to the Grid Code, the DSO is obliged to send remote measurement results to the TSO when connecting generating installations of a power plant to the grid. They must provide real-time data on the total active and reactive power supplied by power plants with a rated active power between 200 kW and 1 MW, with separate reporting for wind turbines, wind farms, and solar power plants.
This ensures that the DSO maintains transparency and accountability regarding the performance of connected power plants, facilitating better grid management and integration of renewable energy sources.
Every year, a DSO submits to the Estonian Competition Authority and the TSO an estimate of the total prognosticated demand for usage capacity in its service area for the following seven years. Every year, TSO presents to the ECA an estimate of the total prognosticated demand for usage capacity in the entire transmission network for the following seven years. It also submits a detailed plan on how it intends to provide network services to satisfy the demand. The network development has to be based on a transparent ten-year plan, which the DSO formulates at least every two years. It includes the investments for the next five to ten years, the possibilities for connecting new-generation generating capacity and new loads to the network. When formulating the plan, the network operator consults with the users and with the TSO. The TSO’s network development plan includes: the main elements of transmission infrastructure that will be built or renovated in the next ten years, a list of investments for the next three years, a timeline, flexibility services, consumption, trading, and ancillary services. When formulating the plan, the TSO consults with its stakeholders. Electricity Market Act § 66 (2)-(16)
Obligations and rights of plant operators
As stipulated in the Grid Code and Electricity Market Act, every year, electricity producers submit information regarding the metering point for the next fifteen years to the system operator. The producers have to install a meter for real-time measurement. If the rated active power of a power plant exceeds 200kW, then the producer sends the measurements to the control centre of the network operator. The producer has to determine the frequency of verification proceedings on the system’s technical state and notify the system operator. In case of system disturbances, the system operator has the right to demand that the producers adjust their production to the consumption of the production area. Grid Code § 28 (3)
Obligations and rights of customers
Consumers have the right to be notified of modifications in their service areas in at least one daily newspaper of national circulation. A network operator or seller notifies its consumers prior to modifying the terms and conditions of their contract. Electricity Market Act § 63 (6)
Role of the NRA
The Estonian Competition Authority (ECA) monitors the situation concerning market opening and competition, including the prices on the power exchange and the prices set for household consumers, and publishes, at least once a year, recommendations concerning the setting of the prices of electricity sold to household consumers. ECA also ensures that consumers are granted speedy access to their consumption data without charge. Electricity Market Act § 93 (23)
Island-specific rules
In Estonia, the legislation recognises the importance of non-frequency ancillary services—essential for maintaining stability during island operations. For effective island operation, technical conditions must be met, including the need for local power generation and a grid adapted for standalone functionality, according to the Electricity Market Act. The DSO must conduct a public consultation regarding the specification of non-frequency ancillary services and their technical conditions, presenting the results to the Competition Authority, which can reject conditions that do not adhere to principles of equal treatment and transparency.