Solar Geysers vs Heat Pumps

12 Nov 2012

There is general consensus that all South Africans need to switch over to an alternative energy source to heat their geysers.

Eskom says the installation of a solar geyser depends on the system, its size, the type of plumbing you have in your home and the kind of geyser you buy. A solar geyser could cost homeowners anything from R6 000 to R36 000.

This is according to Craig Isaacson, Managing Director of Unlimited Solar, who says in the typical home, the geyser makes up 40 percent of the total electricity bill.

He says with solar or heat pumps aiming to save homeowners 70 percent of their geyser spend, this will translate into about a 30 percent saving on their total electricity bill every month.

The problem facing most South Africans is which technology to go with. There are so many options when it comes to solar geysers and heat pumps, every company canvassing for their share of the market and explaining why their product is best for you.

Isaacson shares a few points that homeowners need to consider before making the choice between solar geysers and heat pumps…

Heat pumps are efficient in how they use electricity and a 1kw input of electricity generally translates to a 4kw output of electricity. This means that the savings on your geyser spend will be similar to that of a solar geyser.

Solar geysers

Isaacson says a solar geyser uses the sun's energy to heat the geyser.

He says any solar water heating system is made up of two main components, the geyser and the solar collector.

He explains that the solar collector is responsible for generating heat and the geyser’s function is to store that heat so that it can be used at the consumer’s convenience.

The most efficient configuration for a solar geyser is called a thermo siphon configuration - this setup means the geyser sits above the collector, usually on the roof, and the heat will rise naturally into the geyser.

If, for some reason, you can’t have the geyser on top of your roof then you can have the geyser sitting inside your ceiling and the panel on top of your roof. In this circumstance, homeowners can then make use of a pump to circulate the water between the geyser and collector.

Eskom says the installation of a solar geyser depends on the system, its size, the type of plumbing you have in your home and the kind of geyser you buy. A solar geyser could cost homeowners anything from R6 000 to R36 000.

Depending on the homeowners' usage habits, how big the family is and what hot water is used for, the estimated savings for households can add up to a potential of 22 percent on their total electricity bill, says Eskom.

Isaacson says the main questions to ask when installing a solar geyser are whether or not the system is frost resistant and if the guarantee on the system is at least five years.

Eskom also offers homeowners who install solar geysers a rebate on all approved systems, offered by approved suppliers and installed by approved installers.

All these details are on the Eskom IDM website, a list of systems, their supplier details, their prices, installation costs, rebates and system details. The rebate is paid directly into a claimant's bank account, eight weeks after the application is received.

Solar systems on the Eskom programme have to have a minimum five year guarantee and a quality solar geyser is estimated to last for 15 to 20 years.

Try to find a supplier who is registered on the Eskom solar water heating rebate programme to make sure that they comply with these and many other requirements.

According to Isaacson, the biggest resistance to solar geysers in South Africa is due to aesthetic reasons; people don’t want to see these monstrosities on their beautiful roofs. He says this is something homeowners need to move past or design around.

Architects are experimenting with new ways to hide solar geysers all the time and this will bode well for new builds.

Should property owners invest in a solar geyser, Eskom says, it would take an estimated 4.5 years for them to recoup on their investment, depending on their hot water usage, the cost of the system, their savings and the tarrifs at the time.

Heat pumps

A heat pump works like an inverse air conditioner. It takes heat particles from the atmosphere, compresses them, pumps them into your geyser and circulates the water round.

Heat pumps are efficient in how they use electricity and a 1kw input of electricity generally translates to a 4 kw output of electricity. This means that the savings on your geyser spend will be similar to that of a solar geyser.

Aesthetically speaking, heat pumps look like air conditioners, so there is little resistance from consumers to placing a heat pump on the wall.

Isaacson says a heat pump is a better option for a family that is consuming hot water throughout the day or an office environment where the draw off is constant.

According to Eskom, the installation costs of a heat pump vary from manufacturer to manufacturer, and depend on the customers’ specific needs. On a typical domestic unit of approximately 250 litres water capacity, the cost of the unit itself would be between 3 and 7 times the cost of an equivalent domestic resistant element geyser - the actual installation cost should be about the same or, in some cases marginally higher.

“The figure for commercial units is probably within the same spectrum, but with a shorter payback period. The costs of domestic units are more in line with a solar water heating system.”

Eskom says customers can buy a heat pump at rebated cost from the accredited, published registered suppliers on the programme, and the supplier must perform a full installation.

“Heat pumps sold by registered suppliers are already rebated by Eskom, so you don’t have to apply for a rebate personally. You get the rebate upfront, without any delay.”

Isaacson says Solar Water heaters take longer to heat up and heat up best between 10am and 2pm when the sun is strongest, while heat pumps perform relatively the same throughout the day. However, solar geysers are able to draw on power twice a day should the sun's heat not be sufficient.

He believes if homeowners have good conditions for a solar geyser i.e. North facing or a flat roof and they don’t mind having the geyser sitting on top of it then solar is the best option.

With the rate that the electricity price is rising, he thinks that solar geysers will provide a better saving over the longer term.

Isaacson says the energy is clean and there will be days that you don’t use any electricity at all.

He says both solar and heat pumps are a great option and the only certainty is that you should be investigating which one suits your lifestyle best. 

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