It will cost around R250,000 to install a power generation and storage system that is sufficient to take a small household off of Eskom’s grid.
This is according to Nick Roche, chief product officer at Rubicon, a South African energy company that distributes solutions like Tesla’s Powerwall backup battery system.
Many households have grown tired of Eskom’s load-shedding and increasing prices and are looking into ways to power their homes themselves.
Roche said that “off-grid” was often used by frustrated consumers who did not fully understand the costs of being completely independent of Eskom.
“It can be very expensive if you want to accommodate enough energy storage to cover a winter storm in your upfront equipment costs,” Roche said.
Although there has been a general trend of decreasing prices for self-powering energy solutions over the last few years, global factors driven by the Covid-19 pandemic have reversed this in the short term.
This includes higher prices for the commodities used to make system components, the increased cost of solar panels due to constrained supply and big demand, much higher international shipping costs, and the general shortage of semiconductors for electronic equipment.
According to Roche, a small entry-level off-grid system now starts from around R250,000, while a premium system with more autonomy could run upwards of R650,000.
Nevertheless, Roche said Eskom’s energy costs have risen to the point that it is now economically viable to be off-grid and get the capital costs back with a return, inside the life of the equipment.
“The other important factor in making this investment decision is how quickly the value of the self-generated power is increasing as Eskom’s 15% 2021 rate hike will comfortably counter the cost increases over its life,” Roche said.
“Grid-supplied energy will cost around 40% more in 2022 than it did in 2019.”
Roche said when it came to the ideal system for households, there was no “one-size-fits-all” solution.
Factors you should consider will include:
- System size – Amount of output power and capacity
- Roof details –Size of the roof section with sufficient exposure to the sun
- Autonomy – How long the system must keep providing power during periods of low generation.
- Budget – How much you want to spend.
Roche said there were a few easy wins to decrease the required system capacity and costs when planning a solar system.
“Firstly, hot water geysers should be converted to alternative supplies such as solar energy,” Roche said.
Next, converting the stove and oven to gas can greatly reduce usage, as these appliances are among the most power-hungry.
Alternatively, induction plates have a much lower electrical load.
Lastly, Roche recommended updating certain other loads or old appliances to energy-efficient options – such as LEDs for lighting or using modern fridge and freezer technologies.
Once you’ve optimised your usage profile, you can consider your installation.
Typically, a solar-based off-grid solution consists of three main components – photovoltaic (PV) solar panels to capture energy from the sun, batteries to store the energy, and an inverter to convert energy from the panels and battery into useable electricity.
Roche recommended looking into the following brands for the various components in an off-grid system:
- Inverters – Goodwe, Enphase, Studer and Synapse
- Solar panels – JA Solar, Canadian Solar and Longi
- Batteries – Tesla and Synapse
Roche said various other reliable brands were on the market but warned to be on the lookout for low-quality options.
Roche said Rubicon found that an average household required a minimum of a 5kw inverter, but in many cases, something a bit larger is needed.
“The storage capacity depends on the load profile and how much of the generated energy needs to be stored for each average daily cycle,” said Roche.
It also depends on how much autonomy you want — how many days you would like to run without significant generation, such as during a winter storm.
“Each additional day’s autonomy is a significant cost,” Roche said.
He explained that in the case of an off-grid design, it becomes a trade-off between how many days of the year you’re prepared to run a relatively inexpensive generator versus the significant upfront cost of additional battery storage.
Roche recommended the following specifications for an off-grid system suitable to the average household:
- Inverter output – Minimum of 5kW
- Battery storage – 10kWh to 20kWh
- Solar array generation – 3kW to 5kW
Aside from the price of the above, you will have to consider costs for wires, interconnecting components, and installation.
Roche provided the table below as an example of a cost breakdown for an off-grid system with 10kW maximum power output and 20kWh storage.
|Off-grid system cost breakdown|
|2 x 5kW Synapse inverter||R24,000|
|4.5kW solar modules||R24,000|
|20kWh battery storage||R100,000|
|Balance of system (battery rack, cables, mounting structure, switchgear, surge protection etc)||R25,000|