On-Grid vs. Off-Grid Solar PV Systems

Already battle-weary when it comes to a traditional reliance on a functioning national grid, rumours of the imminent introduction of new, yet-to-be-explored stages of load-shedding events have many South Africans escalating plans for a move away from this dependence on a national energy supply. Solar PV is proving one of the most popular means of independent power generation for many homes across a predominantly sun-drenched South Africa. 

Of the three main types of solar PV systems available, the homeowner has a choice between being off-grid, partially off-grid (hybrid) or on-grid, the latter also known as grid-tied.

As the name suggests, off-grid implies that the home is no longer connected to the national grid. Via a series of solar photovoltaic panels, energy from the sun’s rays is sent to an inverter that converts this DC into alternating current (AC) required to power most household appliances and switches. These systems will have to incorporate a relatively substantial battery storage setup able to recharge from excess energy throughout daylight hours for use during none PV generation periods.

While the idea of being completely off-grid and thereby no longer reliant on a national power provider may seem enticing, in most cases a hybrid (partially off-grid) setup offers both the peace-of-mind of grid-drawn power should your solar PV system or its accompanying battery storage prove inadequate, this is the most common methodology used during the current load shedding crisis.  These systems can also be configured to feed excess power back to the grid.

An on-grid solar PV system is one that remains mated with the national grid. While prioritising power harnessed from the sun’s rays, should the energy requirements of the home outweigh what is being delivered by the solar panels, these systems can seamlessly switch to draw current from the established grid. Conversely, one of the advantages of a grid-tied system is that it can send excess energy back into the grid, thereby triggering any number of both current and touted provincial government rebate schemes.  Unfortunately, these systems do not operate with out a grid reference, this can be from the national utility or for example, a generator.

Established in 2001, Rentech is perfectly poised to offer expert advice to assist customers in choosing the best solar PV product and power solutions, appropriate for specific applications and requirements.