The geyser is by far one of the biggest electricity guzzlers and installing a heat pump or solar water geyser can dramatically reduce your energy consumption, save you thousands of Rands over the years on your electricity bill and make a significant contribution to ‘greening’ your home or business. Furthermore, if you have plans to generate your own electricity by means of photovoltaic solar power (PV), you need to work towards getting your property ‘PV-ready’ and reducing your electricity usage – the geyser is a primary starting point.

But what water heating solution should I choose – solar or heat pump?

There is no right or wrong answer and your decision will depend on a number of important considerations that you should discuss with a reputable supplier that can provide you with a broad range of technology and solutions based on your specific needs analysis.

We often see clients who have called us in to help them after they have been fobbed off with a system that is not ideal for their needs, simply because their original supplier only offered one specific technology and their sales person did a great number on them. The result is often insufficient hot water and a poor realization on electricity savings, and an unhappy client.

Both solar and heat pump technologies have vast energy efficiency and environmental benefits and are complementary technologies on saving energy. Your choice will depend on the capital you have available for the initial purchase, the projected savings and thus payback period you require, your motivation for updating your method of heating water, your usage as well as the site and technical aspects of the installation. Consulting with a reputable supplier like One Energy means you will get access to a range of products across both heat pumps and solar systems and we’ll do a thorough needs analysis to help you to weigh up the alternatives and make the right choice.

How does a solar geyser work?

Solar water heaters use the radiation from the sun to generate heat. The size of the solar panel will determine how much energy can be collected from the sun. For example if you have a 4sqm or bigger flat plat solar panel connected to a 300L geyser, this should give you 300L of 60°C water at the end of a warm sunny day. The same applies with an evacuated tube system, whereby the bigger your geyser, the greater the number of tubes you need to heat your water.

During cooler days with less sunshine you may still need a geyser element to supplement your hot water heating usage. Today, solar systems are installed with very smart timing systems which allow you to specify time zones for when you want to have hot water, for example at night between 6pm and 9pm when you take your bath, and again in the morning between 5am and 8am. Your system will work to ensure that you always have hot water during these times to the specific temperature. If the temp drops to below your specified requirement and there’s no sunshine at that time to reheat it, your system will kick back to the geyser element to supplement your hot water. It will only do this if necessary, so the savings are significant. In fact, a properly-sized solar geyser can cut your monthly electricity bill by anywhere between 30-40% of your total cost.

When going solar, as a rule of thumb, each person in the household uses around 70 litres of hot water a day. Check with your supplier about the size and the power output of the system. An under-sized or low efficiency system will result in insufficient hot water and a poor realisation on electricity savings, defeating the whole purpose of why you bought the system.

How does a heat pump work?

The heat pump uses a small amount of electricity to extract a lot of the latent heat energy from the surrounding air. So a heat pump is also using the energy from the sun but only indirectly and so it can work day and night, winter and summer. The efficiency of a heat pump is called the COP (Coefficient of Performance). A COP value of 4 means that the heat pump produces four times as much thermal energy as what it uses electrically – in other words a 75% saving on the water heating bill. Using a COP value of 4, a high efficiency 4.7kW heat pump takes about 3 hours to re-heat a 200L geyser from a cold start. This enables you to always have hot water at a fraction of the cost no matter when or how much water you use. Unlike the solar option, a heat pump also requires virtually no change to your lifestyle and routine as it is not limited by the availability of the sun for heating. The main advantage of a heat pump is the ability to re-heat a geyser a few times per day and that it can work day and night, rain or shine.

Bulk water heating solutions

One Energy provides bulk water heating solutions for commercial, industrial and agricultural applications in line with SANS regulations. Already large scale solar thermal, which for convenience is described as 5 000 litres of hot water and above, is providing businesses with an investment where capital invested can be paid off in as little as 5 years or less.