With no end in sight for load-shedding in South Africa, many people are looking for backup power to carry them through the outages.
Small backup systems like power trolleys and UPSes might be able to run a limited set of devices, such as a TV, laptop, some lights, and a router.
Energy experts previously told MyBroadband that a fully-fledged off-grid system could cost the typical household upwards of R500,000.
An excellent middle-of-the-road solution is an on-grid inverter-and-battery system that can charge from Eskom power and discharge during an outage.
The Tesla Powerwall is a well-known option globally and has been available in South Africa through Rubicon Renewables since 2018.
It proved so popular that it sold out and was superseded by the Powerwall 2 in South Africa in December 2019.
This premium all-in-one system combines a battery, inverter, cooling system, and smart control and reporting capabilities into a sleek package.
The Powerwall 2 comes in a single 13.5kWh capacity which can be stacked for more demanding homes or businesses.
13.5kWh should be more than enough to last most typical South African homes during load-shedding.
According to Eskom, the average household consumes around 900kWh of electricity per month, roughly 30kWh per day or 1.25kWh per hour.
The Powerwall features a built-in inverter that can provide 5kW of continuous power or 7kW peak power.
That makes it capable of starting up and running several appliances simultaneously, aside from notoriously power-hungry appliances like electric stoves and ovens, water pumps, geysers, or tumble dryers.
Unlike other lithium-ion batteries, the Powerwall 2 has a rated Depth-of-Discharge (DoD) of 100%, which means you can consume all of its useable capacity without losing long-term battery life.
You manage the Powerwall 2 with a dedicated mobile app, simplifying control and system monitoring.
This combination of premium features comes with a hefty price tag compared to batteries of a similar size.
At the time of publication, the Tesla South Africa website listed its price at R170,300, excluding installation.
The local rival
One of the most reputed local battery brands used by several South African solar installers is Freedom Won.
The South African company was founded in 2012, initially as an electric vehicle (EV) converter.
In 2015, it launched its LiTE range of LiFEP04 batteries, with capacities ranging from 5kWH to 2,500kWh.
The closest to the Tesla Powerwall in terms of capacity is the LiTE 15/12 battery, offering a recommended discharge depth of 80% and a maximum DoD of 90%.
That means it is only safe to use between 12kW and 13.5kW of its total capacity before your start to lose long-term battery life.
At prices of around R95,000 to R100,000 from various online stores, the Freedom Won battery is substantially cheaper than the Powerwall.
However, it is missing one crucial component — an inverter.
The battery supports inverters with up to 24kW peak power output and 15kW continuous power, much more than the Powerwall 2.
Inverters of this size come at a substantial cost and would not make sense for most households.
Freedom Won’s batteries are often paired with the Dutch brand Victron.
For comparable performance against the Powerwall 2, the Victron Multi-Plus-II 6.4kW inverter can be connected to the Freedom Won battery.
It costs around R50,000 with accessories needed to connect it to the battery.
Both batteries come with 10-year warranties, with their manufacturers guaranteeing a minimum retained capacity of 70% after this period.
If that is not the user’s experience, the battery should be eligible for a free replacement.
Bear in mind that Freedom Won only guarantees this performance for up to 4,000 cycles at an average DoD of 80% and a maximum of 90%.
Tesla guarantees the retained capacity after an unlimited number of cycles over ten years.
Another important consideration is where you plan to put your battery system.
While the Powerwall 2 has protection for both indoor and outdoor use, the Freedom Won battery is only suited for indoor use.
The table below compares the specifications of the Tesla Powerwall and Freedom Won Lite Home 15/12 battery.
|Battle of the load-shedding batteries|
|Specifications||Tesla Powerwall 2||Freedom Won Lite Home 15/12|
|Useable capacity||13.5kW (100% DoD)||12kW (80% DoD)
13.5kW (90% DoD)
|Depth of Discharge (DoD)||100%||80% recommended (90% maximum)|
|Environmental protection||Indoor and outdoor
-20 to 50 degrees Celsius
|Rated for indoor-only use|
Minimum 70% retained capacity
4,000 cycles at an average 80% DoD and maximum 90% DoD
Minimum 70% retained capacity
|Service life||Estimated 20 years||16 years at an average 80% DoD over 5,500 cycles
20 years at an average 50% DoD over 7,500 cycles
|Dimensions and weight||745 x 490 x 290mm (130kg)||1,150 mm x 753 mm x 147 mm (114kg)|
|*When paired with Victron Multi-Plus-II 48/8000/110-100 6.4kW inverter and remote control system.|