Grid Tie Inverters

Grid Tie inverter- So called because they connect the the Grid Supply (Eskom) and feed solar energy back to the Grid – these systems are very intelligent, usually bigger systems, and a Battery back-up does not form part of the greater system.

These systems are usually not practical for homes/dwelling but more for offices - which have only day-time occupancy.

These systems are Grid-tied in such a way that whenever photovoltaic power is available, it will use that power as first priority, but when no photovoltaic power is available, it is then drawn from Eskom.

The Solar Array on these systems is usually linked to the rating of the inverter itself. E.G. a 3KW inverter will have a 3kW solar array. Power from the alternative source is thus only available when the sun is shining.

Inverters used here are typically SMA, Victron and for Big systems of 100KW upwards - Hitachi/ Siemens/ABB.

The understanding of the differences between the various systems is very important in order to understand the respective cost implication associated with each system.

The Grid Tie system is at this stage the most cost effective system, but has no backup facility or any batteries. So whenever you have SUN available your Grid Tie system supports and supplies power to your network. If you have a lot of solar panels and harvesting more than you actually use, the extra power is effectively sold back to Eskom — so Eskom becomes your battery bank.

In Many countries houses/offices and factories which are Grid Tied are allowed to sell electricity back to the grid and being compensated for it. Some municipalities in South Africa do allow connection to the grid, but in general it is still not legislated.

In May of 2015 Nersa moved closer to finalizing the legislation

The latest published Small scale regulatory rules- herewith (Click link)

These days various very good makes of Grid Tie inverters are available, The Price range is just as wide. At PlanMyPower, we focus mainly on the German system SMA. Although we installed various others, reliability of such an system is crucial.