South Africans have been pummelled by large electricity price increases since electricity shortages and load shedding started in 2008. Electricity prices increased by more than 500% in real money terms over this period – in other words, 5 times more than inflation (see our blog article on this topic).
This rapid and sustained rise in electricity prices, combined with increasing concern about the health and environmental impacts of South Africa’s ‘dirty’ coal-fired electricity, has prompted a search for ways to reduce our dependence on the grid.
Water heating is the single biggest energy consumer in South African households at 40% of total household energy use(ref). That makes it an obvious target for reducing the electricity bill.
South Africa’s National Building Regulations also prescribes minimum energy efficiency standards (through Regulation XA), which requires all new residential properties to derive at least 50% of the annual household water heating requirement from an energy source other than grid electricity.
There are many options for heating water, including:
Solar PV (photovoltaic)
Solar thermal (also called ‘solar geysers’)
Natural gas or LPG
PVT (PV thermal – a combination of solar PV and solar thermal)
With so many options for water heating, the inevitable question is: which is best?
Like most things in life, the answer depends on your priorities and circumstances. Things like location & climate, size of household, budget, reliability of electricity supply and importance of environmental considerations all have an impact on the suitability of available water heating options.
However, there are clear advantages to some options over others. Let’s first look at cost.
When considering the cost of any system, it is important to also consider total lifetime cost. This includes the upfront cost of the system and installation (capital cost), as well as anyongoing costs, such as electricity or fuel costs, maintenance and repair costs. One must also consider the lifetime of the system.
There is a methodology to account for all the above factors called Levelized Cost of Energy (LCOE). It calculates the total cost per unit of energy (called a kWh or ‘kilowatt-hour’) for different energy options.
The graph below shows the overall cost or LCOE for several water heating options in South Africa as of 2021 (see tab “Levelized Cost of Energy” at ref):
It is clear from the above graph that solar PV and solar thermal water heating are by far the lowest cost options for heating water. The most expensive option is in fact electricity from Eskom or the municipality!
Heat pumps require maintenance and have ongoing electricity costs, while gas is expensive and fluctuates with changes in oil price.
Of course, there are several other considerations when deciding between different water heating options.
The table below compares some of these factors for the three most common alternative water heating options: solar PV, solar thermal and heat pumps.
Additional plumbing required?
Retrofit to standard electric geysers?
Some designs can be retrofitted
Some noise (pumped systems)
Works during power failures?
Yes for some (thermosiphon & pumped with solar PV)
Yes (requires more expensive indirect system)
Not as good
Not as good
Overheating & water wastage?
Yes (stresses system & wastes water)
Not good for thermosiphon & requires stronger roof
Good (if hidden)
Yes – every few years
Yes – annual
Comparable or less expensive than pumped solar thermal. Less expensive than heat pumps
Thermosiphon solar thermal systems are cheapest
10 – 15 years
10 – 15 years
Roof space required
2 – 3 x more than solar thermal
2 – 4 m²
None (but requires space for system)
Lifetime cost of energy
Worst (continue paying for electricity)
Section 12B tax benefit for ‘build to rent’ property developers?
Based on cost and all the considerations in the above table, solar PV and solar thermal are clearly preferable to heat pumps. (There are some situations where heat pumps are the only practical option – for example multi-storey buildings with insufficient roof space for solar PV – although carports or other ground mounted solar PV can help overcome this issue).
If upfront cost is the overriding consideration, thermosiphon systems (the systems with the tank on the roof) are the lowest initial cost option. However, when system lifetime and maintenance cost are included in the calculations (in other words, when looking at lifetime cost), solar PV is the most cost effective.
When considering factors such as winter performance, noise, power failures, maintenance requirements, overheating and water wastage, solar PV is preferable to solar thermal.
Whichever option you prefer, it has never made more financial and environmental sense than now to switch to alternative ways of heating water!
PowerOptimal, a leader in innovative sustainable energy and demand management solutions, has announced that it has partnered with the South African subsidiary of Swedish global appliance giant Electrolux, to bring cost-effective, sustainable solar photovoltaic (PV) water heating solutions to the South African market.
This exclusive partnership will see the PowerOptimal’s Elon solar PV water heating technology sold alongside Electrolux’s leading Kwikot Superline electric water heaters (geysers). With deployment of the PowerOptimal Elon range, a customer can add solar capability to most standard electric geysers, without the need for an inverter or battery. It is the most straightforward and most convenient means to take advantage of solar and traditional power in an existing solution.
“We are very pleased to announce our partnership with PowerOptimal. The company’s sustainable energy solutions align perfectly with our global commitment to sustainability, which is to shape living for the better”, states Mark Moyce, National Sales & Marketing Director at Electrolux South Africa. “By including the Elon into our range of water heating solutions, we are offering developers, builders and all users of geysers a means to take advantage of the abundant solar resource we have in this country at a fraction of the cost.”
According to both parties the partnership makes perfect sense, as the organisations are an excellent cultural fit, the technologies integrate seamlessly, and the technical excellence from both are providing a superior technology solution designed to support and grow mass adoption of sustainable energy.
The innovative PowerOptimal Elon range enables direct connection of solar PV panels to standard electric geysers. It requires no inverter and no batteries, is cost-effective, offers a long lifespan and requires almost no maintenance, making it one of the lowest cost per unit of energy (kWh) solutions for water heating available on the market today.
“We are honoured to partner with Electrolux. The company’s market coverage, quality standards, and market-leading customer service make them the perfect partner for our Elon solution,” states Richard Fearon, CEO at PowerOptimal. “Through this exclusive partnership, all PowerOptimal water heating solutions will be recommended and exclusively sold by Electrolux in South Africa. Together we are looking forward to leveraging the technical capabilities of both companies to bring sustainable energy to a larger market of people, previously inhibited by the sheer cost of solar PV technology.”
PowerOptimal’s Elon range solution can run entirely off the grid, or with grid AC power as backup. In addition, it can be used by property developers for conformance to SANS 10400-XA’s Regulation XA2, which requires that at least 50% of the annual water heating requirement for all new buildings shall be from a source other than grid electricity.
PowerOptimal designs, develops and builds sustainable energy solutions that redefine the future of energy. Headquartered in South Africa and founded in 2014, PowerOptimal’s team draws from their collective engineering and commercial expertise to enable global organisations and consumers to reduce energy cost whilst achieving the sustainability goal of net zero carbon. The company’s innovative and patented energy demand management and solar photovoltaic water heating systems are designed to reduce consumption, demand and cost by leveraging the abundant solar resource.