As energy costs continue to rise and tariff structures shift, many South African businesses are turning to solar PV systems to reduce their electricity bills. A key distinction many overlook is the difference between a standard grid-tied solar system and grid-tied solar with battery storage (BESS) specifically designed for energy arbitrage.
What is a Grid-Tied System?
A grid-tied solar PV system is connected directly to the municipal or Eskom grid. During the day, solar energy is used to power the site. When solar production exceeds on-site demand, that excess energy may be exported to the grid (depending on metering rules).
These systems help businesses reduce the volume of electricity they buy during daylight hours. However, grid-tied systems have two key limitations: they offer no backup during outages, and they cannot shift energy use across tariff periods.
What About Grid-Tied Solar with Battery Storage?
This is where the game changes. The system charges the battery during low-cost periods, either from excess solar or off-peak grid supply, and discharges during expensive peak tariff windows. This isn't about resilience — it's about pure cost optimisation.
Lower Costs, Higher Returns
By designing a BESS specifically for arbitrage, and not for backup, you can install:
- A smaller inverter, since it doesn't have to carry the full load
- A smaller battery, since it only needs to cycle for peak periods
- No changeover or isolation systems, since it doesn't need to operate in island mode
The result is a much more affordable solution that still delivers high-impact financial returns.
Why It Matters for Businesses
With TOU tariffs now widely adopted, the ability to shift your energy use is more valuable than ever. This approach works best for:
- Businesses with solar PV already installed
- Operations with afternoon or evening demand
- Clients on TOU tariffs like Megaflex or City Power
- Anyone looking to increase solar ROI without overcapitalising
It's Not Backup; It's Strategy
Grid-tied solar with battery storage for arbitrage is not a backup solution. It's designed to lower your energy bill every day by shifting when you use electricity, not just how much.
