The connection to the grid is regulated by legislation [1], [2], of which the most relevant is the Commission Regulation (EU) 2016/631 of 14 April 2016. Notification of connection of an installation to the grid can be made by several types of entities: individuals, sole traders, companies (most often micro, small and medium-sized companies) and other legal entities. The conditions for connection derive from Commission Regulation (EU) 2016/631 of 14 April 2016 establishing the Code NC RfG (Network Code Requirements for Generators). It is an Act whose application in the legal orders of the EU Member Nations is direct (i.e. it does not require direct acts).
The Code has defined types of generating units due to the different voltage level at which the generating units are connected and the maximum generating capacity.
These are summarised in a table on Fig. 1.

If the facility equipped with photovoltaics is already connected to the grid of the distributor, and the capacity of the installation does not exceed the connection capacity, the connection can be made on the basis of an application. If, however, the building is not connected, or the photovoltaic power is greater than the connection capacity, the connection shall be made on the basis of an application. In that case, it is necessary to apply for an increase in the connection capacity or to adapt the energy connection to the planned increase in the connection capacity. The subsequent connection stages are presented in Fig. 2.

The connection procedure is free of charge. The most common and simplest are the so-called micro-installation connections. A micro-installation is defined as an installation where the peak power does not exceed 50 kWp, at the same time the installed power cannot exceed the connection power (defined in the service agreement). The Act on Renewable Energy Sources (RES) contains a number of simplifications for the so-called prosumers [3]. Prosumer is a combination of the words 'producer' and 'consumer'. A prosumer is a consumer involved in the production of the goods consumed, in this case energy.

A renewable energy prosumer is a final consumer, who produces electricity exclusively from renewable energy sources for their own use in a micro-installation, provided that, in the case of a final consumer who is not a household consumer of electricity, this does not constitute the object of a predominant economic activity defined in accordance with the provisions issued pursuant to Article 40(2) of the Act of 29 June 1995 on public statistics (Dz. U. z 2019 r. poz. 649 i 730).

In such a case, the connection shall be made on the basis of the application submitted. The application contains the applicant's data, data of the building connected to the grid where the micro-installation was built, data of the micro-installation to be connected (number of modules, power, inverter data) and additional information. Detailed lists of documents and applications are presented by specific distribution network owners.
The act defines the response time to the application, e.g. the application of the applicant not equipped with a source, who wants to be connected to the grid above 1 kV, will be examined within 60 days. The application of an applicant equipped with a source should be processed within 120 days. After verification and approval of the installation application, the network owner installs the bidirectional meter. The relevant contract governing the cooperation (sales or distribution contract) is then signed. In the case of prosumers, i.e. people who also produce electricity for their own use, a comprehensive contract is signed.
In the case of changes concerning the system (change of capacity, suspension of production lasting from 30 days to 24 months, termination of electricity generation), the consumer is obliged to inform the energy company.

Sample applications:
TAURON – Mikroinstalation
Energa – Installation notification