Energy16.01.2024

Cheapest time to go off-grid — How much it will cost to wave Eskom goodbye

Typical South African households will pay anywhere between R167,000 and R529,000 to go fully off-grid, depending on electricity consumption habits and the type of setup they want.

It is currently one of the most affordable times to buy a solar and backup battery system in South Africa.

The costs of solar panels, inverters, and batteries are at their lowest ever due to oversupply and less demand after a period of surging imports in early 2023.

For those who want Eskom out of their lives entirely, there is the option of severing your connection to the grid.

Doing so will require substantially more money than installing a backup system capable of supplying 80–90% of your demand.

An off-grid system has to be over-engineered with more solar panels and batteries to account for periods with very low solar availability.

In the table below, we’ve specified four off-grid solar and battery systems available from Solar Advice for homes with varying electricity consumption levels.

All the systems have been overspecced with double the output and storage capability.

According to Eskom, the average South African household consumes 900kWh of electricity per month.

Such a household would need to spend over R400,000 for a fully off-grid system with sufficient backup capacity for two days without solar power.

Fully off-grid system without generator
Monthly consumption  450kWh
(15kWh per day)
600kWh
(20kWh per day)
900kWh (30kWh per day) 1,200kWh
(40kWh per day)
System components
Solar panels 12 × 455W Mono Percium panels 16 × 455W Mono Percium panels 24 × 455W Mono Percium panels 32 × 455W Mono Percium panels
Inverter 2 × LuxPowerTek 5kW off-grid inverters 2 × LuxPowerTek 5kW off-grid inverters 3 × LuxPowerTek 5kW off-grid inverters 3 × LuxPowerTek 5kW off-grid inverters
Batteries 6 × Shoto 5.12kWh Shoto Lithium-Ion 8 × Shoto 5.12kWh Shoto Lithium-Ion 12 × Shoto 5.12kW Lithium-Ion 16 × Shoto 5.12kWh Shoto Lithium-Ion
System specifications
Peak solar output 5.46kWp 7.28kWp 10.92kWp 14.55kWp
Peak power available 10kW 10kW 15kW 15kW
Monthly generation 901kWh 1,201kWh 1,802kWh 2,402kWh
Total backup capacity 30.7kWh 41.0kWh 61.4kWh 81.9kWh
Hours on backup with 0kW solar output 48 hours
Costs
Total price with installation R224,492 R282,577 R412,466 R528,637

It would be possible to have a grid-tied solar system with Eskom’s power as a backup for a fraction of the prices in the table above.

Even considering that you have to spend more on a hybrid inverter than an off-grid unit, not having to account for periods without sunshine can cut system costs by a third or more.

Another benefit of being grid-tied is that you can feed excess electricity back into the grid where municipalities allow it.

In the case of the systems above, all power that cannot be consumed or fed into the battery will go to waste.

However, it is important to note that Eskom wants new electricity tariffs in South Africa to include higher capacity charges.

This will carry a high cost for those who only use the grid as backup power, while the effective price per kWh of electricity will get cheaper if you use more.

Another alternative to an overspecified configuration is to supplement your system with a generator to supply power during periods with limited sunshine.

The table below summarises the specifications and price of the systems for the same users as in the previous table, but with a supplementary fuel-based generator.

The costs do not include fuel or other running costs.

Fully off-grid system with generator
Monthly consumption  450kWh
(15kWh per day)
600kWh
(20kWh per day)
900kWh (30kWh per day) 1,200kWh
(40kWh per day)
System components
Solar panels 6 × 455W Mono Percium panels 8 × 455W Mono Percium panels 12 × 455W Mono Percium panels 16 × 455W Mono Percium panels
Inverter 2 × LuxPowerTek 5kW hybrid inverters 2 × LuxPowerTek 5kW hybrid inverters 3 × LuxPowerTek 5kW hybrid inverters 3 × LuxPowerTek 5kW hybrid inverters
Batteries 2 × Shoto 5.12kWh Shoto Lithium-Ion 4 × Dyness 3.6kWh Lithium-Ion 5 × Dyness 3.6kWh Lithium-Ion 5 × Shoto 5.12kWh Shoto Lithium-Ion
System specifications
Peak solar output 2.73kWp 3.64kWp 5.46kWp 7.28kWp
Peak power available 10kW 10kW 15kW 15kW
Monthly generation 450kWh 601kWh 901kWh 1,201kWh
Total backup capacity 10.2kWh 14.4kWh 18kWh 25.6kWh
Hours on backup with 0kW solar output Sufficient for full overnight demand
Costs
Solar system with installation R130,579 R165,786 R219,454 R253,550
10kW petrol generator R36,995 R36,995 R36,995 R36,995
Total price R167,574 R202,781 R256,449 R290,545
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