Many South Africans who have not yet invested in off-grid features for their homes are seriously considering doing so as load shedding intensifies in the country.
The cost of these power solutions and the technicalities involved can, however, be a little scary.
The key to knowing what you need and your reasons for wanting to be independent of Eskom will help guide you to the type of home system that you need.
To do this, you need to understand the three stages of going off the grid.
Stage 1
The first thing to do, says Christiaan Hattingh, managing director of AWPower, is define what the term ‘off-grid’ means to you.
“Does it mean reducing your monthly electricity bill to a minimum or does it mean not having a grid connection at all? If it means reducing your monthly electricity bill to a minimum, understand your home set-up.”
This means knowing what you consume and when.
“Heating and cooling systems, such as geysers, underfloor heating, and aircons, are typically the highest energy consumers along with loads that run for extended periods of time, such as pool pumps and security lights.”
Other factors he says you should ponder include whether you have LED lights installed, if you are using warm water from the geyser to wash your dishes instead of boiling the kettle for the warm water, and if your pump is on a timer.
Once you understand how much energy you consume daily (kWh units) and throughout the year, a correctly sized system – inverter, batteries, and panels – can be designed around that information.
“If you are unsure about this, a load measurement exercise can be done by your installer to analyse your consumption over a period of time.”
Echoing this, Georgina Smit, technical head at the Green Building Council of South Africa (GBCSA) says you need to get intimate with your household energy use before going off-grid.
“You really need to understand where power is used and when is your highest demand in order to drive efficiency. Firstly, ensure that you have optimised the energy efficiency performance of your home. This speaks to things like energy efficiency lighting, good insulation, appropriate solar control on your eastern and western-facing façades, and appliances that use minimal energy.
“Following that, installing a solar thermal water heating system to heat your water for showering and in the taps is a must, given that water heating accounts for 30% to 40% of an average homeowner’s energy bill.
“Lastly, installing solar PV that converts the sun’s energy into electricity will transition you to be off the grid, and independent of the Eskom supply,” she says.
If you want to go completely off-grid, with no grid connection at all, Hattingh says you need to know the limitations of your chosen energy system based on its size and generation capability during the various months of the year, such as the energy production from the PV panels.
“The benefit of understanding what you use and when, is that you will pay for a system that is correctly sized to your needs.
“Going the solar route is a lifestyle decision, and once you have experienced the benefits and the control you have, you will not go back.”
Stage 2
A hybrid inverter system is a solution that most households opt for to get themselves partially off-grid. The benefit of a hybrid system, Hattingh says, is that you don't have to oversize a system and spend a lot of money to reduce your monthly bill because you have the grid as a backup, especially during bad weather periods.
“The system can provide savings from solar and the stored battery power during normal on-grid operation, but is also able to provide power to essential loads from the battery and solar – if available, during load shedding or power outages.
“These systems can be expanded over time, giving you more flexibility to fit your budget and needs.”
In terms of pricing, Hattingh says you are looking at a minimum of R100,000 to start with a small system consisting of an inverter, battery, and panels installed by qualified installers.
Stage 3
Homeowners who want to be completely free of Eskom do have a clear picture of what they use and when they use it. They are energy-conscious and typically incorporate gas for cooking and even water heating at times
Hattingh emphasises that it is vital to understand the limitations of the system installed.
“The inverter size determines what you can use at any given moment. The battery size and capacity have to match the inverter size and the general rule of thumb is a 1:2 rule as a minimum.
“For example, for a 5kW inverter, 10kWh battery capacity is typically required. The number of panels installed needs to be able to power the loads during the day but also charge your batteries to 100%. This is especially important during winter periods and means that you would have excess capacity during sunny months.
“For periods of continuous bad weather, a generator could be incorporated to charge the batteries.”
In general, Hattingh says, a completely off-grid system is two to three times more expensive than a partially off-grid one due to the need to oversize for bad weather months.
* Understand the cost of going off-grid and why it may not work for you.
* You can also learn about some financing options for alternate energy features here.
*There is a downside to going completely off-grid.