Years of Eskom load-shedding have pushed many South African households to source their electricity supply from outside the national grid.
Things are not expected to get better at the utility any time soon, with its own forecasts for the next three months showing it anticipates shortages in supply.
One of the options for South Africans to generate electricity and power their own home is solar power panels combined with a battery backup system.
Photovoltaic (PV) solar panels are able to capture light from the sun and convert this into energy.
This is then transferred to a backup battery or combination of batteries which are either lithium-ion or lead-acid based.
While many consumers have opted for smaller grid-tied systems and only use their own power during load-shedding, others have completely gone off-grid so as to be completely independent.
With Eskom aiming to charge solar users a fee for having the grid as backup, many more may now be considering going off the grid completely.
Eskom has also announced it will increase electricity prices in April this year, which gives South Africans even more motivation to generate their own power.
Lifting the load
While fully-fledged home power systems are still relatively expensive in South Africa, there are several ways to make such an installation in your home more affordable.
These include power-saving interventions that could drastically reduce the capacity and generation requirements of the solar panels, inverters, and batteries, which would mean you can spend less to meet your demand.
One of the easiest ways to do this is to replace conventional incandescent lights with power-saving LEDs.
The average LED bulb uses about 10x less energy than an incandescent bulb with the same luminance.
Items which use elements – such as electric stoves, ovens, heaters, and geysers are power-hungry appliances which can be switched out for gas variants.
Lastly, for those appliances which have to use electricity, like refrigerators and washing machines, it is recommended that you opt for machines with AAA+ Energy ratings.
These consume around 30% less electricity than A-rated appliances.
Once you have made these adjustments, you can measure your average usage every month to see what you would require.
Choosing a provider
There are numerous solar energy companies which offer a variety of pre-configured solar energy systems.
Solar Advice is one such company, with an online store offering a wide range of solar panels, inverters, and batteries.
It enjoys a score of 8.6 out of 10 on HelloPeter’s Trust Index, with an average rating of 4.98 out of 5 from 49 reviews.
Customers are able to configure a solar build according to their exact needs in terms of capacity and output.
The site also offers a useful calculator which lets you determine how much electricity you consume every month based on your typical bill and the amount you pay per kWh.
We used SolarAdvice’s configurations to calculate how much an off-grid solar-battery-inverter system would cost for certain types of users.
While lead-acid batteries are cheaper than lithium-ion, we chose to use the latter type in our comparison due to their suitability for deep-cycle discharges and longer operation before replacement is required.
The latest lithium-ion batteries are capable of lasting 10 years or longer if properly cared for, compared to around 6 years for lead-acid, meaning they are far more cost-effective options.
All the prices include additional components such as switches, wiring, mounting kits, brackets, plugs, fuses, and connectors.
Eskom’s average user – R188,113.20
According to Eskom, the average South African household uses around 30kWh per day or 900kWh per month.
Based on an average electricity selling price of around R2.50 per kWh for a home in Johannesburg, that would equate to a monthly bill of R2,250.
In order to meet this type of electricity demand, you would require a solar panel array capable of producing at least 30kWh on a daily basis.
From Solar Advice, this would require at least 14 x 390W Mono Percium solar panels which are exposed to the sun for as much of the day as possible.
Assuming that 70% of the electricity consumption of the household happens during the day, that would mean that 21kWh is consumed during the day, while 9kWh would be used at night.
The latter would require at least an equivalent battery capacity in order to keep the house powered while the sun is not available.
For sufficient power output at any given time, you can combine two 5kW inverters for a 10kW output.
Including the installation cost of R53,900, a solution of this size will be priced at R188,113.20.
- 14 x 390W Mon Percium solar panels
- 2 x Growatt 5kW inverters
- 1 x Growatt 9.6kWh battery
The man in the middle – R133,621.03
Realistically speaking, however, most middle-class households will likely use much less than the daily 30kWh Eskom has claimed.
If you have an average monthly bill of R1,500 and pay R2.50 per kWh, this would mean you use around 750kWh per month, or 16.7kWh per day.
With 70% of usage throughout the day and 30% at night, your usage will be split into 11.7kWh during the day and 5kWh at night.
The system on its own would be priced at R96,821.03, while installation will add another R36,800 (excl.VAT) for a total of R133,621.80.
- 8 x 390W Mon Percium solar panels
- 2 x Growatt 5kW inverters
- 2 x Pylontech 3.5kWh Lithium-Ion batteries
The lightweight – R80,383.57
Assuming you have a smaller home and rack up an average monthly bill of R800 with R2.50 per kWh, you consume around 320kWh per month.
With a daily consumption of 10.7kWh, you will need far fewer solar panels and a smaller battery capacity to keep your household powered.
Provided that your output requirements are lower as well, you can save by only using a single 5kW inverter instead of the two used for the previous setups.
On its own, this system would be priced at R60,883.57, while installation will set you back a further R19,500 (excl. VAT).
In total, you can expect to pay R80,383.57 for the following combination of components and installation:
- 5 x 390W Mon Percium solar panels
- Growatt 5kW inverter
- Fusion 4.8kW Lithium-Ion battery