Shopping centre owners across South Africa are switching to solar to save on electricity costs, reduce their reliance on the grid, and transition to using more sustainable clean energy. While the promise of solar energy is vast, the reality presents challenges, and solar PV systems come with their own set of complications.
For one thing, a mall’s peak energy consumption rarely aligns with the hours of peak solar production. In an ideal world, shopping centre owners and tenants could shift their electrical loads to coincide with the solar production timeframe, which is an average of seven daylight hours in winter and eight in summer.
In reality, however, high-consuming ovens and chillers must be started hours before the sun rises: bread must be baked, gyms need hot water for showers and ambient temperatures must be controlled in time for the morning rush. Malls with longer opening hours and kitchens that operate in the evenings face the same problem at the end of the day. Added to this is the ongoing reality of load shedding, especially if you have a grid-tied solar PV system.
While there is no one-size-fits-all solution, in this article we cover several strategies that you can adopt to ensure you get the most out of your solar energy plant. Importantly, these strategies assume that the design of your solar energy system has been properly tailored to your centre’s specific needs.
A first step in reducing the strain on your solar PV system is to promote energy-efficient practices in the shopping centre as a whole. Switching to LED lighting, heat pumps, gas ovens and more efficient chillers can collectively reduce overall energy demand. Here, securing tenant buy-in and collaboration is essential.
In order to optimise your system, you need to understand how much power is being consumed at what times, and by what equipment. We suggest engaging the services of a load management specialist to perform a thorough energy audit. They will consider load patterns and peak consumption, giving you a picture of your energy usage that goes beyond the usual logging exercises performed during system design.
Using data from the energy audit, a load management specialist can develop a load management plan. This plan will align peak energy demands with solar generation and mitigate the effects of power outages. For example, high-energy activities, such as air-conditioning and water heating, would be shifted to coincide with periods of available solar power.
Incorporating a Battery Energy Storage System (BESS) and/or diesel generator can provide backup power. This will ensure continuity of power when the grid goes down. (Note: grid-tied solar PV alone will not produce power during load shedding, even if the sun is shining.)
While generators typically have lower initial capital costs than BESS, they can bring their own set of complications if they’re not properly maintained or if overused. Not to mention the eye-watering diesel costs many South African malls are paying. These systems can also be profitably combined (especially useful if you already have a generator on site). Here, the BESS would handle routine load shedding events, and the generator would stand by as emergency backup for extended outages.
Backup technologies have the added benefit of enabling peak shaving. This is the practice of reducing or “shaving” the highest points of energy demand over a specific period. For example, a shopping centre can store excess solar energy produced during low demand periods in a battery, and then consume this stored power during peak demand hours. This would effectively reduce their electricity costs and grid reliance during expensive peak times.
The good news is that we can automate these processes. Smart meters can monitor grid power availability and adjust energy consumption based on real-time solar output and load shedding periods so that only essential circuits receive power at specified times or when the grid goes down. They can also facilitate peak shaving.
There are costs involved in taking this approach. For example, you may need to rewire your tenants’ distribution boards. In addition, careful technical monitoring must be in place to ensure that load management meters communicate effectively. However, there’s great value in optimising solar electricity loads and increasing operational and economic efficiency.
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Shopping centres in South Africa continue to go solar in the face of rising energy costs and insecurity of supply. By using these strategies to manage energy consumption, retail property owners can make the most of their investment, reducing costs and increasing their energy security along with the sustainability of their operations.
