Solar Water Heating Systems

The Suka Solar water heating (SWH) is the conversion of sunlight into heat for water heating using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions for our customers in Ghana. SWHs are widely used for residential, commercial such as the hospitality sector and some industrial applications.

A sun-facing collector heats a working fluid that passes into a storage system for later use. SWH are active (pumped) and passive (convection-driven). They use water only, or both water and a working fluid. They are heated directly or via light-concentrating mirrors. They operate independently or as hybrids with electric heaters.

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t.

There are two types of active solar water heating systems:

Direct circulation systems

Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.

Indirect circulation systems

Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

Passive solar water heating systems are typically less expensive than active systems, but they’re usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:

Integral collector-storage passive systems

These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.

Thermosyphon systems

Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.

The use of solar radiation as heat energy is known as solar thermal heating. This is not to be confused with photovoltaics, which is the production of electricity using sunlight. The great opportunities of the use of solar energy have long been recognised: Our tried and tested technology has proven itself over many years.

• Endless amounts of energy, free of charge
• No CO₂ emissions during operation
• Cost savings: remarkable less energy to heat water, remarkable less energy for space heating
• Reduced consumption of fossil fuels
• Solar thermal systems can be integrated into existing systems
• Modern systems work efficiently even in winter

Solar thermal works in the following steps:

1. The collectors absorb the sunlight via the absorber. Here, a special heat carrier fluid is heated up.
2. A pump transports the fluid to the heat exchanger of the solar storage.
3. Should the solar radiation be insufficient to heat up the water, a conventional heating system will heat up the storage tank to the desired set temperature.
4. A solar thermal system supplies depending on the design annual average approximately 60% of the necessary energy to meet the hot water needs.

In addition to the domestic hot water production, the fluid heated up in the collectors may be used to support heating of the domestic hot water. This method provides an interesting support to the heating unit operation and it offers significant savings potential. Thus, even with moderate temperatures, the heating unit can often remain switched off thanks to solar heating support.

The core of this solution is a combination cylinder, e. g. a buffer cylinder combined with a domestic hot water unit. If there is enough solar radiation the fluid contained in the solar heating system heats up the water in one of the cylinders via the lower heat exchanger. In case of a temperature decrease, e. g. because you take a good long bath or shower, then the heating unit will be switched on as needed via the second circuit. It will then support the additional heating of the water.

Evacuated tube collectors – Highest solar yields from the tube
The functional principle of the evacuated tube collector is that they absorb the solar radiation via absorbers and then transfer it in form of thermal energy to a fluid.

However, in contrast to flat-plate collectors, the evacuated tube collector utilises the excellent insulation capacity of a vacuum. That’s why they are called evacuated or vacuum tube collectors. Heat losses are almost completely avoided thanks to the vacuum in the glass tube. In addition, a mirror is mounted below the individual tubes to focus the sunlight towards the absorber pipe. All in all, the evacuated tube collectors are significantly more efficient than flat-plate collectors.

• Greater energy efficiency, good yields even with less sunlight and diffuse light
• Require less roof area for the same output
• Can also be used on non-south oriented roof surfaces
• Produces higher temperatures and can be coupled with high-temperature heating systems

The Sukasol evacuated tube collector is the collector of choice for all those voting for the optimum utilisation of solar energy. Due to their mature design the evacuated tube collector achieves the highest possible energy yield even in case of inclined sun position and diffuse sunlight continuously high solar yields, and in total, the maximum possible energy yield.