Selected Energy
 May/June 2012Minimize

Which is best – a solar water heater or a heat pump?

Choosing the correct renewable energy hot water solution is a difficult decision for many homeowners. In light of all the options and conflicting information available, we compiled a detailed list of the advantages and disadvantages of solar water heaters and heat pumps, in order for you to make an informed decision.

There are a couple of factors that should be considered before deciding on a system – the amount of hot water the system needs to provide, the space and budget available as well as the architectural guidelines of estates (if applicable). 

The correct product for the correct application

Besides considering the advantages and disadvantages of both solar water heaters and heat pumps, it is important to choose the correct product for the correct application.

A heat pump, for example, is the ideal solution for a holiday home, especially in coastal areas where the humidity is high and the water quality is good. A solar water heater is the ideal solution for homeowners across South Africa, as it provides sufficient hot water regardless of the weather and water quality.

Heat pump: advantages

  • Easy installation: The installation of a heat pump doesn’t require intricate plumbing work and is fairly easy to install, on both a commercial and residential level.
  • Minimum space requirements: A heat pump needn’t be installed on a roof, and can be installed outdoors.
  • Hot water 24/7: Because a heat pump relies on electricity, it can provide hot water 24/7 when there is dependable electricity supply.
  • Savings: Heat pumps can save up to 50% of energy required to heat water - this translates into a 20-30% saving on a household’s electricity costs.

The Synergy is an excellent heat pump offering from Solahart. It features true top down heating, which means that it takes the coldest water from the bottom of the tank, heats it in a single bypass, and deposits it to the top of the tank, for immediate use (on average 70 liters per hour recoverable). The Synergy is also a sanitised system, which very few heat pumps are. This means that if there is a failure in the exchanger, the oil from the pump cannot get into the hot water system (plumbing) of the home. The Synergy also features an electrical backup element that is placed midway through the tank.

Heat pumps: disadvantages

  • Water quality plays a major part in selection. Heat pump manufacturers do not warrant their systems if the hardness of the water is higher than a certain level. The calcium carbonate in the water solidifies and falls to the bottom of the tank. After a while, the sediment starts to block the heat exchanger. (Corrosion and blockage of the heat exchanger due to poor quality water isn’t covered in the warranty).
  • Hard water (water with high levels of calcium carbonate) needs to be treated with a water softening plant, resulting in high cost implications.  Maintenance of the salt levels is vital to ensure the 'recharging' of the ion exchange.
  • The correct placement of heat pumps is essential. To ensure sufficient savings, the heat pump either needs to face north, east or west. If the heat pump faces north, it will influence the aesthetics of the home (if built to face north). Heat pumps are also noisy, and generate the most noise after hot water consumption (at night, early in the morning). The noise level of a heat pump is measured at 50 decibel.
  • A retrofit heat pump does not replace your existing water storage tank. However, a Synergy heat pump is installed with its own water tank – the existing water tank is removed and replaced with a new storage tank.
  • Heat pumps are less efficient than a solar system in high radiation and low ambient temperatures. This makes a solar water heater more ideal for our winters, where we have cold clear sky. A heat pump will lose 50-70% of its efficiency in sub 5 degree temperatures (a heat pump needs heat from the atmosphere to convert cold water to hot water)
  • If the water isn’t softened – the system will become less efficient, and the warranty will not cover the repairs.
  • Heat pumps require a lot of maintenance, due to constant moving parts that needs to be replaced from time to time. Maintenance on a heat pump also requires the skills of a plumber, electrician or aircon technician.
  • The lifecycle of a heat pump is 5-10 year, and is completely dependent on electricity to generate hot water

Solar water heater: advantages

  • A Solahart solar water heater has a 5/10-year factory warranty, depending on the model.
  • The lifecycle of a Solahart solar water heater is 20+ years – our oldest system is 30 years old and still running.
  • The quality of water doesn’t influence the system - a sacrificial magnesium protective anode and double ceramic lined tank prevents corrosion. A Solahart solar water heater also handles the issue of calcium carbonate better, as it can be easily scooped out during routine maintenance.
  • The thermostat and element of a solar water heater last longer as it’s only being used 10% of the time.
  • A roof mounted solar water heater doesn’t rely on electricity to provide hot water when the sun is shining. All systems have a backup element, which means that your household will always have hot water regardless of the weather.
  • Solahart comes in 9 different colours to match any roof.
  • There is a variety of solar water heating options available for homeowners who don’t want a solar tank on the roof.
  • The payback period on a solar water heater is low, with a high return of investment.
  • A solar water heater is safer than a conventional geyser because the system is installed on the roof.
  • A solar water heater can save up to 90% on your household’s water heating costs. This translates to 40 to 50% saving on your total electricity bill.*

Solar water heater: disadvantages

  • High capital upfront investment and installation costs (in comparison to a heat pump in areas with GOOD quality water, otherwise the initial capital costs are the same)
  • A solar water heater works optimally when the sun shines, if it is overcast, the back-up element kicks in to compensate for the lack of solar energy. The back-up element will operate approximately 10% of the year.
  • Routine maintenance similar to an electric geyser is needed on a solar water heater, but only on the valves and not on the system itself.
  • If the water storage is sized correctly, the costs of a solar water heater and heat pump solution are similar. Replacing 2 x 150 liter geysers with 1 x Solahart system, or adding 2 x 4KW output heat pumps to each existing geyser results in the same financial investment.

For more information on Solahart solar water heaters and heat pumps, click here or contact us.





SYSTEMS - Dr. Riaan Rankin & Dr. Martin van Eldik, M-Tech Industrial (Pty)Ltd / North-West University Februay 2008


*Estimated savings based on water heating costs for a family of five people using 300-litres of hot water a day in Gauteng

 Solahart solar water heater installation  Solahart solar water heater installation Solahart solar water heater installation  

New Solahart dealer for KZN Inland

After exchanging the Johannesburg skyline for the hilltops of the central Drakensberg, Mike Wellbeloved founded Effective Energy_SA with his brother Antony, a registered plumber and his father Kevin, who has been in the building industry for over 30 years.

“Since 2005 Kevin has been a developer at Cathkin Estate in the Central Drakensberg. We have only recently decided to branch off from his existing business to create Effective Energy_SA, servicing and supplying solar hot water heating systems to the KZN Inland area.”

Mike’s brother Antony has been working closely with Kevin and gaining building experience since completing high school and his trade qualification three years ago.

“Kevin acts as a mentor for Antony - sharing his knowledge and experience of how to run a business. Antony does all the installations and maintenance, and I’m responsible for all sales and marketing,” explains Mike.

Effective Energy_SA covers the areas from Mooi River all the way up to Harrismith, and brings solar water heating solutions to towns such as Escort, Ladysmith, Dundee, Colenso, Bergville, Winterton, Vrede, Warden and Vryheid to name a few.

“We do not only sell new solar hot water heaters but also attend to call outs for maintenance on existing Solahart systems installed in our area."

Follow @MikeWellbeloved and the Efffective Energy_SA team on Twitter for up-to-date information on their installations and services.

New Solahart dealers

Selected Energy would like to welcome the following dealers to our distribution network.

KZN Inland: Effective Energy_SA – Mike Wellbeloved

Pretoria: E-Motion Consulting – Brandon Harding

Cape Town: Kruger Constructions – Haden Kruger

For more information on available dealership opportunities, contact Ray Fernandez.

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