If you're on a bulk Eskom supply, be it rural or urban, and are considering a solar installation, understanding how your tariff structure will evolve is very important to realising long-term savings. Eskom offers Time-of-Use (TOU) tariffs tailored for different contexts, and matching your solar system to the right one will make your investment pay off.
For rural bulk-supply clients, Eskom’s Ruraflex tariff is the default TOU offering. It features seasonally adjusted peak, standard, and off-peak energy rates. But there’s a catch: winter peak rates can more than triple off-peak rates. Winter is also typically a high consumption period, and it’s not unusual for some Ruraflex customers to see up to 70% of their annual energy use concentrated in just those three months.
The first step is to register your SSEG and migrate to a TOU structure under Ruraflex. From there, the focus should shift to smoothing out your usage profile using low-cost, operational strategies. Activities like rescheduling irrigation, filling collector dams during off-peak periods, and storing heat or cold for later use in agricultural processing can significantly reduce peak demand without requiring capital-intensive investments.
Once these practical changes are in place, adding batteries or a dispatchable generator can further enhance reliability and savings. A hybrid setup may offer the best long-term economics, but only after the simplest and most cost-effective efficiencies have been implemented.
Urban bulk clients typically fall under Eskom’s Miniflex tariff (formerly Megaflex for smaller industrial and commercial users), which also follows TOU pricing, but with less extreme peak/off-peak differentials than Ruraflex. It’s often presented as the logical next step for solar installs, especially when planning for exports or load-shifting, and it can be a great fit. Net billing improves the economics of exports, solar generation aligns well with TOU periods, and flattened loads can reduce demand charges.
While Miniflex offers compelling advantages, switching to it isn’t automatic. Eskom applies strict criteria before allowing tariff migration. Customers must meet minimum demand thresholds, have compatible metering, and where embedded generation is involved Eskom conducts its own technical and commercial assessments before approval.
Even when approved, Miniflex only delivers value if your load profile plays along. The structure assumes that you can reduce or avoid consumption during peak periods. If you don’t have solar, batteries, or active load management in place, you risk replacing one expensive bill with another.
Consider a small-town shopping centre, where most energy use is driven by air conditioning systems, supermarket fridges and freezers and lighting during daytime business hours. Even before solar was introduced, the demand naturally aligned with standard and off-peak periods, making the site well-suited to Miniflex. But not every site has that luxury.
Whether you're on Ruraflex or Miniflex, the real gains only begin when you actively manage your loads. Simply switching to a TOU tariff won’t save you money unless you also change how and when you consume power.
This means targeting operational changes that reduce demand during peak periods. For example, staggering equipment startups rather than switching everything on at once, and moving shift changeovers outside of peak times. Thermal processes can be pre-heated before peak tariffs kick in, and operational flexibility, like starting machines at slightly different times can make a significant difference. In some cases, ice storage or thermal heat storage systems can serve as viable alternatives to batteries.
Timers and automation can help fine-tune your load profile in real time, but ultimately, smart operational discipline is the foundation of any successful TOU strategy.
Installing solar is a smart move, but it’s only part of the picture. Once your system is registered and you're on the correct TOU tariff, the real impact comes from how you manage your energy use.
The biggest savings often come not from technology, but from shifting and shaping when and how electricity is used. If your operations can adapt to avoid peak periods, whether through scheduling, thermal storage, or process timing you’ll maximise your returns. Batteries and generators can add further value, but only after the low-cost strategies have been fully used.
TOU tariffs like Miniflex and Ruraflex can work well, but only if your load profile and operational habits support the structure. And ultimately, the cheapest electricity is still the kilowatt-hour you don’t consume during peak times.
