There is a burgeoning interest in rooftop solar photovoltaic (PV) power solutions for domestic, commercial and industrial applications in South Africa in 2016 as end-users from all sectors of the economy show their increasing determination to reduce their reliance on Eskom.
Concern over power reliability, possible load-shedding and looming electricity price hikes characterised the past year, persuading an increasing number of end-users to opt for solar power, which continues to be seen as an attractive, cost-effective solution, particularly when compared to diesel or petrol powered generator alternatives.
Decisions to select solar power as the "go-to" option were often supported by developments in solar technology in 2015, including the release of utility grid-connected, hybrid solar PV power systems capable of functioning as back-up rather than complementary power sources in the event of a power outage.
These systems can be operated in three modes: linked to the electricity grid (grid-tied); as grid-tied unit with battery backup (in a hybrid configuration), or as stand-alone hybrid units. In line with uninterruptible power supply (UPS) and other conventional solutions, switchover time from mains to batteries is amounts to 15 ms.
A breakthrough was made in system design and application when South Africa's Soltra Energy released an innovative solution to provide businesses with more effective energy returns from rooftop solar systems.
Conventional wisdom maintains that solar PV panels should be orientated northwards in the southern hemisphere to allow for the most efficient power generation. The result, from a power production standpoint, is a bell curve reflecting power increases throughout the day, peaking at midday and gradually falling again to zero at sunset.
In mid-2015, an iterative evaluation process involving a grid-linked hybrid solar PV application for a Johannesburg-based company was undertaken in which various solar PV system configurations were tested. The outcome roved that a convention-breaking east-west orientation of solar panels can often be more advantageous for a business application.
The motivation for the tests was that the Eskom electrical power supply was often unable to meet the business' full demand. A complementary challenge was also met – to reduce the aggregate electricity cost for the facility.
South Africa has also seen a major step-up in battery storage technology in 2015. The prevalence of routine load shedding and power outages has exposed one of the Achilles heels of standby power devices. This is the shortened lifespan of batteries when subjected to full depletion on a regular basis. This includes specialised, sealed, deep cycle valve regulated lead-acid (VRLA) batteries.
These batteries are not designed to cope with load-shedding. They're intended to backup sensitive equipment such as computers for brief periods during which petrol/diesel generators take over or operators execute a safe power-down.
A period of load shedding, usually ranging from two to four hours, can fully deplete a battery pack. If repeated often enough, the batteries' life can be reduced to around less than six months.
Last year the market witnessed the launch of the SA-designed "long-run" battery pack geared to obviate this problem. Brought to market by Powermode, the Q-on LR battery system is based on the principle that the key to battery longevity lies in a thorough understanding of the status of batteries in terms of their duty cycles and load factors.
In the case of the long-run battery, the knowledge is facilitated by technology built into the battery pack. This includes a computerised battery balancing harness that automatically reports – via a cloud-based portal – on a range of parameters associated with individual batteries in the pack.
Like its American counterpart, the SA-manufactured Soltra Energy Wall is designed to store excess energy, whether it is derived from the Eskom grid, from solar panels or a combination of both as found in increasingly common hybrid systems. The space-saving unit represents a leap forward in battery storage and is expected to boost the acceptance of rooftop solar PV-plus-battery solutions in 2016 and beyond, giving SA consumers greater control over their energy usage.
Efficient battery storage could quickly become one of the biggest game-changers in the South African energy landscape, which will continue to be characterised by a mismatch between demand and supply.