The sun’s energy is fed to connected loads where the user wants a guaranteed supply, and the excess is used to charge the battery. Once the battery has been fully charged, the system starts behaving like a grid tied system, and any excess energy if fed to the energy intensive appliances as well, the air conditioners and pool pumps etc. This ensures that as much as possible of the available solar energy is used, and the user gets the full return on investment for the PV panels.

To further extend the use of solar energy when the sun does not shine, the battery drain can be programmed, for instance set at 50%. So, when the sun goes down, the battery energy is used to supply BOTH the critical loads, and the rest of the house. When the battery reaches 50% state of charge the loads will be fed from Eskom. In the event of a power failure, the batteries will be allowed to drain completely, supplying only the critical loads.

The beauty of these systems is that they can be installed at a much lower cost compared to a traditional “off-grid” system, and they are fully modular, so the user can keep adding panels and batteries over time to become fully independent of Eskom.

Three-phase ESS

A three-phase ESS system has at least one Multi installed on each phase.

Intelligent optimisation of the balance between the phases

ESS intelligently optimises the balance between the phases – as far as possible. While doing so, it will never charge on one phase whilst discharging on another. To better understand how it works, read these examples closely:

When the phases are in balance the situation is simple. Let’s say each phase is consuming 500 W, and only a small amount of PV power is available – 100 W on each phase. Each phase requires another 400 W …a total of 1200 W for all three phases. So 400 W will be drawn from the battery on each phase, and the draw from the grid will therefore be 0 W. Each separate phase will also be at 0 W.