Photovoltaic architectures for self-consumption

There are two main possibilities for connection and operation of PV systems installed on a building rooftop, car park, or integrated in the building structure – self-consumption and grid export.

In the export-to-grid operation, the PV installation is connected to the electrical distribution network and it does not interfere with the building electrical installation. Although physically linked, the PV system and the building installation are two independent and autonomous units.

In case of self-consumption, the PV system is connected to the building electrical installation where the PV production is used in priority to satisfy the electrical consumption needs of the local loads.

Fig. P26 – Installation including PV (renewables) for self-consumption

As there is a physical connection between the two installations, the self-consumption of PV production comes with specific installation rules and architecture requirements.

Electrical installations with local PV generation for self-consumption could be designed to operate:

• only grid-connected - In case of blackout at the electrical network side, the electrical installation is no longer supplied by the local generation.

Current PV systems used for self-consumption operate mainly in this mode.

• grid-connected and islanded – the electrical installation operates connected to the grid, but can also operate in an off-grid mode supplying the totality of the loads or part of them with the local energy sources. Today PV installations cannot assure the operation of the electrical installation in off-grid mode standalone, as the produced PV energy is volatile, predictable, but unplannable and with limited control capabilities. To assure an off-grid operation, PV installations must be associated to another major and stable source such as Storage or Generator.

Also, the operation of the electrical installation in both grid-connected and island mode is much more complex and requires a dedicated control. This kind of operation is rare, especially in countries where the electrical grid is stable and blackouts are abnormal.

This section focuses on electrical installations with local PV production operating grid-connected, which is the main use of PV systems in the case of self-consumption. The specific requirements for installations with PV production for self-consumption are explained and guidelines for sizing and equipment selection are provided.