For shopping malls, rooftop solar is a no-brainer. It’s no surprise then that Resilient real estate investment trust (Reit), which owns a portfolio of retail centres, has invested big in alternative energy. To date, it has spent around R500 million on installing solar photovoltaic (PV) systems, and it is ahead of other landlords in terms of generation capacity.
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By the end of this month, it will have 43.5MWp (megawatt peak) of capacity installed at roughly two dozen of its 27 properties. By the end of this year, a full quarter of its consumption will be from its rooftop solar arrays (up from 15% in December and 19% at the end of April).
But there’s a problem …
Most of its installations are grid-tied, which means that during load shedding the solar plants don’t generate electricity. This is not unique to Resilient (Vukile also highlighted this last month).
During load shedding, the property owner – like others who have these kinds of solar installations – must use backup generators to power its centres.
This is entirely logical. The supply from solar is not guaranteed (or dispatchable), which is why these kinds of systems are grid-tied in the first place. In other words, if solar PV supply is interrupted by, say, a storm, the demand still needs to be met. And, in the case of the grid supply being cut – during load shedding – there is no ability to balance the load within the property to seamlessly switch over to solar PV.
Of course, the solution to this is batteries.
Homeowners who have inverter and battery backup power systems installed (with or without solar) will know this. The same principle holds for malls, but at this scale an industrial-sized storage solution needs to be used.
Resilient commissioned its two battery pilots in 2021, at The Grove Mall and Irene Village Mall in Pretoria, which has allowed it to test these at scale.
CEO Des de Beer says Resilient has evaluated battery systems “ruthlessly” and been “very careful” with its choice of technology (lithium iron phosphate).
Making the wrong technology choice at this scale could be a very costly mistake.
Resilient head of renewable energy Vishay Rabbipal says the two pilot systems, from different suppliers, are operating within Reit’s expectations. They allow it to “reduce [its] dependence on the grid” and, crucially, to power these properties during load shedding.
The priority now is a mass rollout of batteries across its portfolio.
De Beer admits that there is now a “huge rush” by property owners to install batteries but is confident the company has paid any proverbial school fees with its pilots.
Batteries will be installed at the building (mall) and, where required, at the tenant level, explains Rabbipal.
Executive director Johann Kriek says it has installed ‘powerwall’ type solutions for tenants at the group’s cost.
Currently, there are a 135 of these installed. Resilient charges tenants a fixed cost per month for these to recoup its investment. These “comfortably” handle Stage 4 load shedding – they take just two hours to charge. Kriek says the group has acquired a further 200 of these.
Increasingly, he says, Resilient has started thinking more as an energy producer.
This is changing its whole approach to architecture and to things like building automation. Tenants are very supportive, he adds.
The group can supply power “via batteries at less than half the cost of the grid,” says Kriek. This proposition, together with the scrapping of the 1MW limit on private generation, takes its planned use of solar and batteries beyond the realm of simply clipping demand during the evening peak (effectively arbitrage).
Resilient’s solar PV at Boardwalk Inkwazi in Richard’s Bay is, for now, the largest rooftop installation in the country.
Kriek says this plant produces sufficient power to run the entire centre and to charge the batteries when these are installed.
This is cheap power. It plans to invest hundreds of millions of rands more in its battery rollout, along with additional solar.
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Kriek says Resilient wants to “move away from installing any more generators”.
In future it will rely on solar and batteries to trade seamlessly during load shedding, with generators being in place as backup only.