System 2 – H. Holm Tswane Electrical Department



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Holms and Friends: Atmospheric pressure storage system with 36 m2 collector & heat pump


A local municipality tender to ensure the newly build electrical department building complies to the National Building standard SANS 10400 XA. A very unique “Text Book” installation to demonstrate the following Solar system principles:

  • High Pressure Indirect Glycol circulation trough the flat plate panels
  • Low pressure indirect potable water thermal storage in Polymeric storage technology
  • Indirect high pressure on-demand supply through a “Fresh Water Station” Heat Exchanger

Not the biggest installation, however integrating the technologies in such a way that the system is extremely cost competitive. Conceptualized to attain a very long expected product life (> 20 years).


 What fascinates me about this system is the ingenuity and design skill that has gone into the system. However not local components the potential to localise is high and it illustrates the simplicity to convince the local governments to integrate renewable energy into Government Buildings and the solution to conform to building standards and Energy Efficiency standards.

The system has 36m2 flat plate collectors (thermal capacity = 25.2kWth) conceptualized at low flow with a variable speed, high efficiency, temperature controlled solar charging pump. The collectors are arranged in a combination of parallel and series configuration to avoid high resistance.

The heat exchangers have long lengths with minimal resistance.

The 5000-litre polymeric tank is reinforced with a steel mesh to ensure longevity.

A 36kWth standby heat pump delivers approximately 40 - 45% of the total energy requirement, depending on hot water requirements. The storage capacity allows for the heat pump to only run day time when the CoP is better.

The fresh water station has a 60kW exchange capacity to ensure low temperature feedback water to the storage vessel. Both primary and secondary pumps are of high efficiency class A rating and electronically speed controlled.


Tel: 082 809 0190
Address: R511 ext, 26 Welgegund, 491 JQ, Hartbeespoort, 0216





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