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FAQ Solar Water Heating systems

How much will I save if I replace my electrical element geyser with a solar water heating system?

A high-pressure solar water heating system can reduce your electricity bill by up to 24%

Will a solar water heating system be able to supply me with enough hot water?

Solar water heating systems use the energy of the sun - depending on the type of system you install and how you use it, between 50% and 90% of your hot water requirements could be met by using the energy of the sun

Are there various system sizes?

Yes. Tank capacities range from 100 to 300 litres - the size of tank you require depends on your daily hot water requirements. It is wise to invest in a system slightly larger than your normal daily hot water needs to ensure only one reheat period a day is necessary - choose a system with a capacity of between 50 and 100 litres per family member. (Too much oversizing can be un-economical and cause you to recoup your investment over a longer period.)

Are their factors that could influence the amount of electricity I can save by installing a solar system?

As mentioned above, solar water heating systems can reduce your electricity bill by up to 24%. However, the percentage saving is subject to weather conditions, your hot water usage profile, system orientation and a correctly sized unit. Moreover, the percentage saving is dependent on the system you install and the climate of the region you are staying in

How long will it take me to recoup my investment in a solar system?

Payback periods vary between 5 and 8 years

Does the climate have an influence on solar systems?

Yes. System performance is limited to sunshine hours and can be affected by cloudy and rainy weather. Also, systems are designed to operate efficiently in both frost and frost- free conditions - ‘direct’ systems are recommended for coastal and warmer areas that are frost-free and ‘indirect’ systems are recommended for inland areas that are frost-prone. Moreover, geographical location can influence the size of the panels required to meet your need for a specified amount of hot water

How does a solar system look?

Solar panels are flat, dark-coloured plates or a bank of glass tubes installed on your roof. The panels can be flush with the roof or installed by means of support structures to angle them towards the sun – the installation should be in a sunny, north facing area. The tank of a solar system is large and cylindrical

Are solar systems dependent on electricity?

No

  • However, installing a back-up electrical element is recommended to ensure that you have enough hot water during cloudy and rainy weather
  • Also, it is important to have a timer installed to ensure that the back-up electrical element remains switched off while the sun heats the water to the required temperature of between 55°celcius and 60°celcius. Ideally, the timer should be set to allow the back-up electrical element to come on for only two hours in the morning and two hours in the afternoon - outside 5pm to 9pm, the period of peak demand for electricity in South Africa
  • Important: The technician who did the installation should issue you with an Electrical Certificate of Compliance (CoC)

  • Are solar systems noisy?

    Most systems operate silently. (There is low-level noise when a circulation pump is added.)

    Can I install a solar system myself?

    No

    Systems must be installed by a competent PIRB registered plumber. The timer should be connected by a qualified electrician. (Systems should be positioned as close as possible to where the heated water will be used.) Also, it is important that the plumber who did the installation should issue you with an Electrical Certificate of Compliance (CoC)

    How do I maintain my solar system?

    Systems are relatively low-maintenance:

  • Solar flat plate and vacuum tube collectors must be kept clean and dust free to work optimally and should be washed at least every 6 months in areas with very low rainfall
  • Evacuated tubes need to be replaced when they lose their vacuum or if cracked or broken
  • The glycol in ‘indirect’ systems needs to be checked on a regular basis to ensure optimal performance
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    How does a solar system work?

    Solar technology is advanced; it captures the sun’s energy and transfers it efficiently to heat water. Two types of systems are available – active and passive

    What is the difference?

  • In the case of ‘active’ electrical pumps and controls move water around the system; the two main categories of active systems are ‘direct’, where water moves through solar collectors, gets heated, and collects in a storage tank with the help of electrical pumps and controls; and ‘indirect’, where instead of heating water, the solar collectors heat a ‘heat transfer’ fluid - the water picks up the heat from the fluid (but never mixes with it), and gets pumped into a storage tank
  • In the case of ‘passive’ the forces of nature are used; the two main categories of passive systems are ‘batch’, where a storage tank is situated inside the solar collector, the water gets heated inside the tank and either gravity or natural convection moves water from the tank to your home's pipes; and ‘thermo-siphon’, where the storage tank is separate from the solar collector - cold water moves through the tubes of the solar collector and natural convection pumps the heated water into the storage tank from where it travels to your home's pipes
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    Are there different types of system installations?

    Yes

  • A solar collector with its own tank (and your existing geyser disconnected) is called a ‘standard’ system - direct and indirect systems are available
  • A system that feeds into your existing geyser, which increases the amount of hot water as there are two storage tanks, is called a ‘pre-feed’ system - direct and indirect systems are available
  • A panel that feeds into your existing geyser is called a ‘retrofit’ system - direct and indirect systems are available
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