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Solar Energy Storage: As the heated water from the tubes flow into the storage tank the inflow creates a natural circulation motion in the tank and colder water from the tank flow down flow down the glass tube to be heated up. (See diagram at the bottom of the page.) All the warm water is stored is stored in the insulated tank.

About Solar Tubes

Solar tubes are the absorber of the solar water heater. They absorb solar energy converting it into heat for use in water heating. Solar tubes are also referred to as evacuated tubes, as the space between the two glass layers is evacuated to from a vacuum. Solar tubes have already been used for years in Germany, Canada, China and the UK. There are several types of solar tubes in use in the solar industry. R.T.C. uses the most common “twin-glass tube”. This type of tube is chosen for its reliability, performance and low manufacturing cost.

Each solar tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light rays to ass through with minimal reflection. The inner tube is coated with a special selective coating (AI-N/AI) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the are contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures. This “evacuation” of the gases forms a vacuum, which is an important factor in the performance of the solar tubes.

Why a vacuum? As you would know if you have used a glass lined thermos flask, a vacuum is an excellent insulator. This is important because once the solar tube absorbs the radiation from the sun and converts it to heat, we don’t want to loose it!! The vacuum helps to achieve this. The insulation properties are so good that while the inside of the tube may be 15 C / 340 F, The outer tube is cold to touch. This means that solar tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta T conditions).

In order to maintain the vacuum between the two glass layers, a barium getter is used (the same as in television tubes). During manufacture of the solar tube this getter is exposed to high temperatures, which causes the bottom of the evacuated tube to be coated with a pure layer of barium. This barium layer actively absorbs any CO, Co2, N2. O2, H2O and H2 out-gassed form the solar tube during storage and operation, thus helping to maintaining the vacuum. This barium layer also provides a clear visual indicator of the vacuum status. This silver coloured barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition.

Solar tubes are aligned in parallel, the angle of mounting depends upon the latitude of your location. In a North South orientation the tubes can passively track heat from the sun all day. In and East West orientation they can track the sun all year.

The efficiency of a solar water heater is dependent upon a number of factors, one important being the level of solar radiation in your region. Looking at the chart South Africa is ideally situated in a global sense to exploit the sun’s energy.

Installation Methods:
As this is a low pressure system and the Exhaust / overflow should never be closed. The following diagrams is the most ideal way to install this unit.

At RTC SOLAR we believe that the RENEWABLE ENERGY market, has the potential on a long term basis to leverage electrical savings, to increase employment opportunities, and thus to ultimately help in the reduction of Greenhouse Gas Emissions.

The unit has a integrated tank with high efficiency insulation to minimize heat losses during the night
Unit are supplied complete with stand and brackets. Installation time can be as little as 4 hours.
All materials used on the TASOL heaters are of high quality Stainless Steel Copper Aluminium and glass to ensure longer life. (All recyclable products)
Units that are installed by properly trained staff carry an unconditional 5 year guarantee, providing the water supply is a quality that is supplied by most municipalities.
The vacuum tube technology and high tank insulation permit a very high efficient rate by heating the water much faster and keeping it hot for much longer than conventional flat plate water heaters.
The cylindrical shape of tubes face the sun most of the day. Solar tubes also have reflectors mounted behind them so as to minimize the sun’s energy, which results in a stable heat output from morning till late afternoon.
Model HPS104 High Pressure unit is easy to install. Don’t need a new geyser as unit can be installed to existing facility
Innovative design makes for a quality installation that will be an attractive eye-catching feature of your home. In time we believe it will be the “in-thing” to have on your roof. Unit are supplied complete with mounting rails and brackets. Installation time can be as little as 4 hours.

Specifications: Model 1
Tank Capacity	80 Litres
Tube Capacity	17 Litres
# Tubes	16
Tube Length	1.2 Meters
Total Length	1.3 Meters
Total Width	1.6 Meters
Specifications: Model 2
Tank Capacity	120 Litres
Tube Capacity	25.5 Litres
# Tubes	24
Tube Length	1.2 Meters
Total Length	1.3 Meters
Total Width	1.9 Meters

1. Indirect System:
In conjunction with a solar hot water geyser with an integrated heat exchanger.
Antifreeze liquid is used to circulate between the heat collector and the water-geyser. This transfers the heat that is collected by the collector to the water geyser. This is the preferred method and is particularly suited for areas with poor water quality, as the water will not contaminate the solar collector or pumping station. The expansion tank must be used with the indirect system.

2. Direct System:
In conjunction with a solar hot water geyser without an integrated heat exchanger.
The water from the geyser is circulated through the collector with the circulation pump and heats the water directly. As the geyser has no heat exchanger it is more economical than the indirect system and is recommended for areas of high quality water.

3. Modified System:
For use with an existing electric hot-water geyser:
The existing hot-water geyser is used and the solar hot water system is added and connected by means of a special water-injection nozzle into the geyser. This assures proper mixing of the heated water in the tank. As water flows through the collector, this method may also only be used in areas with good quality water.

4. Thermosyphon:
For use with solar or existing geyser:
This method does not use the pump or controller but rather relies on heat convection to circulate the heated water through the geyser. This is the most economic operation. For this installation the collector must be mounted horizontal and the top of the collector must be at a lower level than the geyser. No controller pump is used as the water is circulated through thermosyphon.