Solar water Heater

With so many different suppliers, and multiple makes and types of systems, if you are considering going solar for replacing electric water heating with solar there are some key questions you need to check.

  1. Are you prepared to have a tank on the roof?
    If you are
    1. There are numerous systems available to both replace the existing electric geyser, or put in a system that pre-feeds the existing electric geyser (normally located in the roof void or attic).
    2. Many body corporates, and private homeowners object to complete systems being put onto the roof as they are not attractive.
    3. Be aware that larger systems of 300l generally will require additional roof reinforcement, (considerable extra cost) as their weight will be substantial, up to 500kg, and the roof was never designed to carry this.
    4. There are no advantages to having the tank on the roof

    If NOT
    1. There are as many solar systems that do not require the tank to be put on the roof. These are generally referred to as split systems
    2. Only the solar collector is put on the roof
    3. The tanks can be located elsewhere, inside the roof void (attic) outside or on the ground, (for example in a garage), if the system is pumped (forced circulation).
    4. Retrofits, where the existing electrical tank is used, reduces the cost of the solar system.
    5. New tanks to enlarge the overall water volume can be added to the existing tank, which are generally located adjacent to the existing tank and run in series.
    6. There are no disadvantages to the tank being located inside the home.
    7. Split systems allow for larger solar collectors, which in turn results in greater flexibility, and enable larger electric savings
    8. From an aesthetic point of view, only having the solar collector on the roof, and not the tank, improves the appearance of the solar system
  2. What size of system do you require?
    1. We recommend strongly that you do an audit of the amount of electricity being used in heating water on a daily basis.
    3. With a good idea of the amount of electricity being used you can choose a solar system that will replace part or all of the electricity used in heating water.
  3. What are the daily kWh savings of the solar system?
    1. For some inexplicable reason many solar water heater suppliers are reluctant to provide this information, which is absolutely essential
    2. Without knowing the kWh output, you are buying on ‘blind faith’ or unsubstantiated sales speak
    3. Do not accept explanations, for example ‘Lots of hot water” or “It gets very hot”
    4. If you buy a system without knowing how many kWh units it is likely to save, in all probability you will be making a mistake and end up disappointed.
  4. What is the efficiency of the system?
    1. A similar question to the number of daily kWh units that the solar system produces.
    2. With the deemed performance of the solar system in kWh units, you can divide the existing consumption from the electric geyser (see point 2 above) by the solar performance to get an efficiency rating.
    3. As a general rule we recommend choosing a system that is close to 100% efficiency
  5. What does the system cost?
    1. The number 1 question from most people, and it is of course very important.
    2. However unless you know what you are getting for the cost, it is no more than a ‘sticker’ in a car window
  6. What is the Payback period?
    1. The best indicator for value for money.
    2. Take the system cost, divide it by the daily savings from the solar system
    3. Take the deemed kWh units saved (see points 3 and 4 above), and multiply by the cost per kWh. At 2017 a good average will be R2,15 – R2,25 including VAT
    4. With the daily savings in Rands, divide that (daily savings figure in Rands) into the system cost to get the number of days payback
    5. Turn the number of days payback into months or years.
    6. Remember the price of electricity is escalating every year by an average of at least 10%, so the payback period will be approx. 10% less than the result in the number of months.
  7. Is the SWH system a SABS tested and passed system or SABS Mark system?
    1. Avoid solar systems that have not been tested and passed by the South African Bureau of Standards (SABS) or don’t carry the SABS Mark
    2. It is illegal to install a solar system that does not have a SANS 151 Mark on the tank.
    3. Avoid solar systems that have imported solar collectors that have not been tested by the SABS in conjunction with a SANS 151 tank, and in accordance with SANS 1307.
  8. Is the supplier and or installer listed with SESSA?
    1. As a consumer in the event of installing a system that is non compliant with the law, you will have limited recourse under the Consumer Protection Act
    2. If you buy a system from a solar supplier that is a member of the Sustainable Energy Society of Southern Africa (SESSA) you will have access (free of charge) to the SESSA Ombudsman, who will rule on the dispute between you as the consumer and the supplier or installer.
    3. We recommend you only buy from SESSA members

Going solar is relatively straight forward if you know what to ask. The Buyer checklist is a guide to getting it right.

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