If the battery can no longer take up excess energy in an off-grid system, the power output of the AC sources in the stand-alone grid is limited by the Sunny Island. This means that the excess energy is not used. The Sunny Island allows for the use of excess energy by means of a multifunction relay.

During the constant voltage phase, a multifunction relay is activated and thus controls additional loads that can put any excess energy to good use. As a result of the utilization of excess energy, the Sunny Island has to limit the power output of the AC sources in the stand-alone grid to a lesser extent.

The energy source of an off-grid system is PV energy. On days with high solar irradiation and low power consumption, the battery cannot take up all of the PV energy during the constant voltage phase. In order to utilize the excess energy, the Sunny Island activates the control of a pump, for example, that pumps water into a container for subsequent use.

The control of additional consuming devices is only possible when using lead-acid batteries. When using lithium-ion batteries, additional loads can be controlled via the load shedding function (from firmware V3.30.37.R, the SOC range can be set up to 100%).

Requirements:

• The technical requirements of the multifunction relay must be met ( > Technical Data).

Cable requirements:

• Conductor type: copper wire

• Conductor cross-section: 0.2 mm² to 2.5 mm²

Procedure: