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Midrand Graduate Institute

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Midrand Graduate Institute – Student residences Plant room 1

  • Total M2 of panels –                      138
  • Tank storage –                                  10 000l
  • Province –                                           Gauteng
  • Year commissioned –                     2013
  • Tank construction –                        Black vessel
  • Liter / m2 –                                        72
  • Back-up heating –                            45-120kW
  • Solar heat transfer to tank –       100kW heat exchanger capacity
  • Stored heat transfer to consumption – 300l/min @ 630kW Heat exchanger capacity

Short description of the thermal hot water system:

CEO of Sonnenkraft SA (Pty) Ltd & SEG Solar Energy (Pty) Ltd, Mr. Werner Sebastian have successfully designed & installed a 10000l solar hot water system for student housing at the Midrand Graduate Institute. Sonnenkraft specialises in the field of solar thermal as well as photovoltaic systems in the residential & commercial markets. State of the art European technology supplied by SEG Solar Energy (Pty) Ltd is used in this closed circuit installation, ensuring low maintenance and high life expectancy.

Sonnenkraft believes in supplying their customers with efficiently designed systems utilising only the highest quality of European technology, installation and products available. Together with their training partners SOLAC Solar academy and AEE Intec, they also strive towards further education & training in terms of renewable energy & system efficiency.

Characteristics of the thermal hot water system at the Midrand Graduate Institute

The 12 000l Solar thermal hot water system is installed with a total of 184m² Flat plate 2.3m2 Mediterano collectors. The plant room equipment includes plate heat exchanger technology, providing a total of 300l per minute instantaneous fresh hot water to the student bathrooms. The plant room also includes stratified charging stations equipped with high efficiency brazed plate heat exchangers ensuring efficient heat transfer from the collectors into the tanks. The back-up heat source used in this installation is a 190kW Riello gas boiler system.

The system was designed as a closed circuit installation using only plate heat exchanger technology in order to transfer heat. The heat that is produced from the solar collectors are transferred into the tanks via the plate heat exchangers in the Stratified charging station. Through this station, heat is stratified into different layers of the storage tanks depending on the temperature provided from the solar system. This is automatically controlled via the solar controller provided as part of the solar station.

The 12 x 1000l storage tanks are also connected as a closed circuit system, these tanks are not internally coated and it is therefore not possible to use it as a flow through hot water system. 100mm insulation is provided around these tanks and with four connection levels from one tank to the next, stratification is possible. Through an integrated plate heat exchanger, the Fresh water modules provide instantaneous fresh hot water up to 300l per minute. The module also includes an integrated hot water circulation pump for the hot water reticulation line. The circulation return is also stratified back into the tanks. The Fresh water module also includes a state of the art controller in order to set temperatures, circulation schedules, etc.

As the Fresh water module provides instantaneous hot water, there is no chance for the formation of waterborne diseases such as legionella and this technology is there for highly recommended for all industries, residential, commercial & industrial applications. Energy efficient Wilo pumps were also used in the above mentioned modules, ensuring low running costs for the whole plant room. The gas back-up is directly connected to the storage tanks (therefor Indirect), assisting the solar system in keeping the water temperature to a required level if needed.

As the only open circuit of this system is the cold water supply to the Fresh water module’s plate heat exchanger, providing instantaneous hot water, the life expectancy of the system is very high with low maintenance required. High quality stainless steel pipe cladding is used with Rockwool insulation, ensuring minimal heat loss in the complete system. This of course also complements the aesthetics of the system. Roof mounting systems are also specifically designed and manufactured for the installation of the Solar Energy collectors, consist of only aluminium & stainless steel, therefor no corrosion is possible.

In order to keep track of system efficiency & maintenance schedules the systems is equipped with Data logging, providing remote real-time data in terms of pump capacities, temperatures & efficiency at any time. This system has been running efficiently since December 2013 and with a positive return on investment the customer couldn’t be more satisfied.


SEG Data Sheets – BS1000 buffer tank
vBus Presentation
SCH-SEG0148 – 12000L System schematic