If there was ever a story that would have you reaching for your rate bill to check your electricity usage, this is it. While we all study the myriad ways in which Eskom’s once-preventable dysfunction affects our lives (don’t go there, you’ll just enrich your cardiologist), the fantasy of getting rid of it is just that for most of us. ‘between us. Disconnecting is not cheap and is sometimes even counterproductive. If you have the disposable income to even get off the grid a bit, chew this item…and do some more homework. Like so many other things in life, the discipline you exercise in your habits—in this case, the highly needed newly formed ones—determines the cost-effectiveness and success of your intervention. A very interesting service story worth tuning into, courtesy of a MyBroadband interview with a power company expert. –Chris Bateman
Goodbye Eskom – the true cost of complete off-grid
By Hanno Labuschagne
South Africans looking to disconnect 100% from the grid without Eskom backup power should be aware that this could come at an unjustified price.
The recent re-emergence of Stage 4 load shedding has angered many, and some have threatened (again) to ultimately sideline the electric utility.
Although some households have installed backup power products to avoid load shedding, these configurations are often grid tied, meaning they still have access to Eskom power when their own systems are insufficient.
While many are tired of the public service’s dismal record to keep the lights on, the truth is that severing ties with the public service isn’t easy — or cheap.
This was highlighted by AWPower managing director and chief operating officer Christiaan Hattingh in an interview with MyBroadband.
Hattingh said while many might be frustrated with Eskom during load shedding, the reality was that grid supply offered huge convenience and cost benefits to households when load shedding was not in effect. To understand why, he said it would be prudent to review how solar home systems work.
Most systems consist of three main components: photovoltaic (PV) panels, batteries and inverters.
Photovoltaic panels generate electrical energy from sunlight, which is transported to an inverter that can convert the energy into a usable form for general household applications. Excess power is diverted to backup battery storage when the panels themselves cannot generate enough electricity to meet a household’s needs.
One of the big problems with these systems is that they have a limited output capacity, which is determined by the inverter.
High performance, cost effective inverters can typically produce around 5kW or 8kW, unlike a single phase home connection which can produce around 13kW of grid power on demand.
With pool and water pumps, stoves, ovens and air conditioners that have high peak power demands, backup systems can often trip unless you are careful to limit your use to a time. given.
Hattingh said going completely off-grid would require a drastic mindset shift where the household becomes very aware of how and when they use certain devices. “If you go the off-grid route, you have to fully commit to knowing your system and what it can do,” Hattingh said.
A key starting point would be monitoring systems that allow you to get a clearer picture of your usage patterns.
AWPower offers Victron Energy inverters, which come with monitoring systems that make it easy to manage your production and demand.
Additionally, while South Africa receives plenty of sunshine to generate electricity, it can also experience long periods of overcast weather. This can reduce the power generation potential of a solar photovoltaic system to around 10-20% of its maximum capacity, significantly reducing the amount of electricity fed into the home’s electrical grid or into home storage. battery.
For 100% off-grid capacity, Hattingh said it’s necessary to oversize your system to compensate for fluctuating solar availability. “Whatever you think you need, you need more than double, triple, quadruple,” Hattingh said.
If you want to continue using electricity without adjusting your usage patterns, large households can expect to shell out around half a million rand for an oversized off-grid system.
Rubicon product manager Nick Roche agrees, saying households using an average of 1,200kWh per month are looking at R727,000 excluding VAT to completely disconnect from the grid. This price also excludes an optional R25,000 generator, which is highly recommended.
However, a system that can meet around 95% of your electricity needs will cost significantly less.
Eskom’s connection service charges in suburban areas are generally not expensive enough to warrant a complete shutdown. Most customers pay around R115 per month for network access.
In cases where it’s not possible to keep Eskom as a backup or where connection fees can be exorbitant, Hattingh advised pairing the system with a generator.
Households can use the generator to recharge batteries on days when sunlight does not provide enough energy to power their home or charge their batteries to a sufficient level.
Hattingh also warned that having the dealer disconnect your grid connection will make your home difficult to sell.
The table below provides a breakdown of three possible grid-tied systems from AWPower that Hattingh recommended for households that use an average of 600 kWh, 900 kWh, or 1,200 kWh of electricity per month.
|Semi-off-grid backup power options|
|Average monthly usage||600kWh||900kWh||1,200kWh|
|Phase||single phase||single phase||single phase|
|Inverter||1 DEYE 5 kW hybrid inverter||1 DEYE 5 kW hybrid inverter||1 DEYE 8 kW hybrid inverter|
|Battery||1 Revov R100 Li-ion battery 5.12 kWh (5.12 kWh at 100%) or
1 Solar® Advanced Li-ion Battery 7.4 kWh (7.4 kWh at 100%)
|2 Revov R100 Li-ion batteries of 5.12 kWh (10.24 kWh at 100%) or
1 x 14 kWh Solar® Advanced Li-ion Battery (14 kWh at 100%)
|1 x 14 kWh Solar® Advanced Li-ion Battery (14 kWh at 100%) or
3 Revov R100 Li-ion batteries of 5.12 kWh (15.36 kWh at 100%)
|Excluded from the quote||Additional load distribution if necessary||Additional load distribution if necessary||Additional load distribution if necessary|
|PV panel size||4.14 kWp (9 panels of 460 W)||6.44 kWp (14 panels of 460 W)||8.28 kWp (18 panels of 460 W)|
|East. electricity savings p/m||R1.368*||R2.401*||R3,283*|
|Recovery period||6.7–7.2 years||5.7–5.9 years||5.2–5.5 years|
|Total system cost (VAT included)||R138,481–R152 124||R196,977–R207,439||R241.713–R257.529|
|Estimation of % of network energy needs and own production||Own generation – 95%
Eskom grid – 5%
|Own generation – 98%
Eskom grid – 2%
|Own generation – 95%
Eskom grid – 5%
|* Based on standard Cape Town home user tariff of R2.40/kWh for the first 600kWh and R3.31/kWh beyond 600kWh. An annual rate increase of 9.06% is assumed for the calculation of the payback period.|
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