A solar water heating system uses solar tubes that are usually situated on your roof to absorb energy from the sun. This energy is transferred into water stored in a hot water cylinder.
What about cloudy days
Although the efficiency of the solar collector is reduced on overcast days it will still be able to heat water for normal use.
On days when there isn’t enough sunlight to heat the water to the desired temperature, backup or ‘booster’ heating may be required to maintain water at the required temperature.
This system will be automated so you don’t have to worry about running out of hot water on a rainy day.
The power of the sun is harnessed in the glass-evacuated tubes, which then heat the super efficient manifold, storing the captured heat. When the water in the manifold reaches eight degrees Celsius above the temperature of the water in the storage cylinder the microcomputer automatic controller starts a small pump.
This pump runs circulating the water until the temperature in the manifold is down to 3 degrees above the temperature in the water storage cylinder. The pump then stops automatically until required again: simple, efficient and effective!
If the water temperature falls to five degrees in the winter the pump automatically starts to circulate the water. This has the effect of preventing the water freezing.
The water in a solar water heating system can be circulated using a pump (an active system) or naturally using a method known as thermosiphon (a passive system). By integrating an active, pumped water circulation system, the location of the hot water cylinder is not restricted to the roof (as with a passive system) and can be sited at any suitable location inside (or outside) the home. A highly efficient electric pump is used to circulate water in conjunction with a controller used to ensure that the pump only operates when it is required.
As you can imagine, an active system is more favoured as not only is it more cost effective when utilising an existing hot water cylinder, it is also more aesthetically pleasing.
Hot Water Cylinders
A hot water cylinder is required to store the water heated by the solar panels until it is required for use.
A solar water heating system also uses a system of controllers, which manage the use of backup (booster) gas or electric heating and can be used to control the pump. The controller ensures that you always have hot water, no matter what the weather outside is like.
Controllers fall generally into two categories; a time trigger controller and a minimum temperature controller. The time trigger controller keeps the booster heating turned off during the day so that you are not paying for electricity or gas to heat your water when the sun can be used, while a minimum temperature controller simply works by triggering the supplementary heating sytem into life whenever the water temperature drops below a pre-set minimum.