Solar Geyser Installation
Durbanville

It depends on four things: whether you are converting the geyser you have or starting fresh, the type of collector, the size of the tank, and what the roof needs before it can carry the load. The City of Cape Town's sizing guide is at least 50 litres of storage per person plus another 50 for the house, which is a sensible place to start. We look at the roof and the existing geyser before quoting, and the quote names the system type, the tank size and every item on it, so two quotes can be compared line by line.

The City of Cape Town puts the saving at up to about 60% of your hot water bill, with payback on a standard flat-plate, close-coupled system typically between three and six years. Winter is the weak season: the long-term average at Cape Town airport is about 176 hours of sunshine in June against 338 in December, so the backup element does more of the work from May to August. Putting that element on a timer is what protects the saving.

Yes, if the geyser is in good condition and its pressure rating can be matched. A retrofit connects collectors and a circulation pump to the geyser you already have, and SANS 1307 requires the solar side's pressure rating to match the existing geyser's. We check the existing tank first, because a retrofit ties new collectors to an old geyser and it is worth knowing how much life it has left. On a new build, or an alteration that needs plans, a full system rather than a retrofit may be needed to satisfy SANS 10400-XA.

Neither wins everywhere. The City of Cape Town describes flat-plate collectors as robust, economical and versatile. Evacuated tubes generally produce more hot water when the sun is weak and the weather is cold, and they are less sensitive to which way the roof faces, but they are more likely to break in hail and can overheat in summer. On a well-placed, north-facing roof, flat plates are the straightforward choice; tubes earn their place where the roof angle or the winter sun is working against you.

A close-coupled system has the tank on the roof directly above the collector, and the hot water rises into it on its own, with no pump and no electricity, so it keeps heating during load shedding. It is the most common and least expensive arrangement. A split system puts the tank away from the collector, for example inside the roof space, and often uses a small pump to circulate the water, which needs electricity but keeps the tank out of sight. A tank under the roof also needs a drip tray, the same as an ordinary geyser.

For a thermal system, no authorisation is needed, but the Water By-law requires the City to be notified when solar hot water panels are installed or changed, and the plumber completes a certificate of approval for the work, which the City processes at no cost to the owner. A PV geyser is different: it must be authorised through the City's small-scale embedded generation process, and the PV geyser switch has to be on the City's list of approved equipment.

Sometimes. The City of Cape Town recommends a heat pump for homes that do not get much direct sunshine, or whose roof lacks the space or the construction to carry a solar water heater, and notes that heat pumps also cope better with coastal fog and haze. A heat pump works off the electricity supply rather than the sun, and Eskom describes it as three times more energy efficient than an element geyser under ideal conditions. If your roof faces the wrong way or sits in shade for most of the day, we will tell you so before quoting for solar.

Have it checked about once a year, which is what the City's guidance suggests. The collector glass needs cleaning, the sacrificial anode in the tank may need replacing every few years, and the lagging on the outside pipes should be checked for perishing. An indirect system also needs its heat transfer fluid replaced on the manufacturer's schedule: Kwikot sets it at three years, and the City's guidance says four to five.