For a business heavily reliant on computers for design, communication, and reporting, ensuring uninterrupted power is critical to combat load shedding and general outages caused by municipal faults. The reliability of the power supply is diminishing, and outages are becoming longer. For an Engineering Consultancy to remain viable, it cannot afford to be without power for extended periods. Until now, MBB Pietermaritzburg has relied on a petrol generator for standby power. However, this solution is noisy, emits unpleasant odours, and requires manual pull starting. Additionally, it necessitates the purchase and storage of fuel, causing inconvenience and frustration when servers and desktops suddenly shut down, leading to lost work and corrupted files.
MBB investigated the installation of a solar system with battery backup and ultimately decided to proceed in June 2023. The system comprises 7.5 kWp of solar panels connected in two strings on the roof, an 8-kW inverter, and a 10 kW.hr 48V Li-Fe battery. This setup is sufficient to power all critical loads, including electronic equipment and lighting, during power failures, allowing uninterrupted work. In the absence of sunlight, the battery can provide around 4 hours of operation. It’s a pleasure to have a quiet and clean backup power source with automatic change-over during load-shedding events.
The system is configured to prioritize self-generation, ensuring that our initial power consumption comes from our sources. We only draw electricity from the grid in case of a shortf;all. Currently, the Municipality does not allow feedback into the grid, resulting in wasted excess power. Solar power aligns well with business needs, as peak power demand occurs during daylight hours when solar panels are most productive. Nighttime usage is limited to a few low-power devices such as security lights and the alarm system.
Thus far, the system has exceeded our expectations. On the sunniest days, it covers nearly two-thirds of our daily energy requirements for the office, and this performance is expected to improve during the longer days of summer. On a sunny day, the system meets all our office’s energy needs from approximately 10 a.m. to 2 p.m., including powering appliances like kettles, toasters, and an electric geyser. It’s gratifying to know that we are not only shielded from the worst effects of load shedding but also reducing our office’s environmental footprint by decreasing coal-generated power consumption. Furthermore, the generator has remained unused since we switched to solar.
The graph below illustrates the monthly energy generation (green) compared to energy imported from the grid (orange) and total consumption (red). June’s data should be discounted as it had only six days of monitoring. In July, we generated slightly less than what we imported, while in August, we generated more power than we imported, with over half of our consumption being self-generated. This trend is expected to continue in September. The middle of summer will be particularly interesting to observe, with longer sunny hours and increased use of air conditioners to keep the office cool.
