In July 2024, the cost of installing a solar power system to fully disconnect a South African home from the grid ranges between R143,000 and R381,000, reflecting a significant drop from earlier in the year. This decrease comes amid reduced load-shedding, though future electricity tariff changes could drive renewed interest in off-grid solutions. While fully off-grid systems are pricier compared to grid-tied ones, they offer independence from grid fluctuations.
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By Hanno Labuschagne
A solar power system large enough to take a typical South African home 100% off-grid costs between R143,000 and R381,000 in July 2024, substantially cheaper than at the start of the year.
Solar power installers have seen a plunge in demand for their products and services due to a significant reduction in load-shedding in the first half of 2024.
However, Eskom’s plans for future electricity tariffs could reinvigorate the industry with households seeking to cut themselves off from the grid completely and avoid higher fixed charges just for having a connection.
Multiple solar power system installers have previously told MyBroadband that going fully off-grid is substantially more expensive than getting a grid-tied system that can meet over 90% of a home’s needs.
The reason for this is fairly straightforward — a fully off-grid system cannot tap into the grid during prolonged periods with little solar generation — like a week of cloudy weather.
MyBroadband used Solar Advice’s configurator to determine the cost of a truly off-grid solar power system for households with varying usage levels.
For the maximum inverter output, we used 10kW for smaller households and 15kW for larger homes.
This would be more than suitable for running even the most power-demanding appliances in most instances.
In terms of solar panel arrays, we used an “oversize factor” of 2.5 on the monthly production. This number was based on solar installers recommending oversizing by two or three times the regular required capacity.
This will help the system charge the batteries as close to full as possible, even during periods with little sunshine.
The same oversize factor was applied to the batteries, although it required a more complex calculation.
Typically, South African households can rely on direct power from their solar panels on most days. The key time of the day when batteries come into play is at night.
Therefore, we also configured the battery storage to be 2.5 times greater than the typical demand at night, which we assumed was 60% of the total daily demand.
The table below compares how much it would cost to go off-grid for households with 450kWh, 600kWh, 900kWh, and 1,200kWh of monthly energy consumption.
Off-grid solar system without generator Monthly consumption 450kWh 600kWh 900kWh 1,200kWh Components Solar panels 15× 455W Mono Percium panels 20× 455W Mono Percium panels 30× 455W Mono Percium panels 40× 455W Mono Percium panels Inverters 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 5× HinaESS 5.12kWh batteries 6× HinaESS 5.12kWh batteries 9× HinaESS 5.12kWh batteries 12× HinaESS 5.12kWh batteries Specifications Peak generation 6.8kWp 9.1kWp 13.6kWp 18.2kWp Monthly production 1,126kWh 1,502kWh 2,252kWh 3,003kWh Peak system output 10kW 10kW 15kW 15kW Total storage 25.6kWh 30.7kWh 46.1kWh 61.4kWh Price with installation R178,736 R210,480 R300,622 R380,993
When MyBroadband previously calculated off-grid system costs, we found the prices for similar systems to those above would be between R224,492 and R528,637.
The price of the entry-level system has dropped by R45,756 — or about 20%. On the top-end system, the new price of R380,993 is roughly 28% of the previous price of R528,637.
It should be noted that the systems above will be capable of generating far more electricity than your home can consume, and there will be nowhere else for that energy to go.
Therefore, households in municipalities with feed-in credits, like the City of Cape Town, will miss out on potential payouts for additional power.
A little bit of combustion
Integrating a fuel-powered generator into your home’s electricity supply is a more affordable upfront alternative to a vastly oversized system relying solely on solar and battery power.
The two major downsides to this setup are that you must pay for the petrol or diesel you consume, and generators are generally noisy while operating.
In addition, generators may have some load limits that prevent them from running at peak capacity constantly and must be serviced regularly to ensure safe and efficient operation.
However, it can significantly reduce an off-grid system’s initial upfront capital outlay because a generator can replace the extra solar power system capacity at a fraction of the cost.
The table below shows how much off-grid systems supported by fuel-based generators will cost for the same usage levels in our previous comparison.
Off-grid solar system with generator Monthly consumption 450kWh 600kWh 900kWh 1,200kWh Components Solar panels 6× 455W Mono Percium panels 8× 455W Mono Percium panels 12× 455W Mono Percium panels 16× 455W Mono Percium panels Inverters 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 2× HinaESS 5.12kWh batteries 3× HinaESS 5.12kWh batteries 4× HinaESS 5.12kWh batteries 5× HinaESS 5.12kWh batteries Fuel generator 12.5kVA (10kW) Mac Afric petrol generator 12.5kVA (10kW) Mac Afric petrol generator 15kVA (15kW) Mac Afric petrol generator 15kVA (15kW) Mac Afric petrol generator Specifications Peak generation kWp kWp kWp kWp Monthly production 450kWh 601kWh 901kWh kWh Peak system output 10kW 10kW 15kW 15kW Total storage 10.2kWh 15.4kWh 20.5kWh 25.6kWh Solar system price with installation R101,407 R124,375 R162,847 R185,815 Generator price (with estimated R5,000 installation) R41,995 R41,995 R69,950 R69,950 Total R143,402 R166,370 R232,797 R255,765
Read also:
🔒 The Economist: Private firms are driving a revolution in solar power in SA and the rest of Africa
South Africa’s solar revolution hindered by persistent barriers
Winter spike leads Eskom to reintroduce load reduction measures
This article was first published by MyBroadband and is republished with permission
https://www.biznews.com/energy/2024/07/22/off-grid-solar-costs-drop
