System 20 – SOLARZONE – Ceres Correctional Prison



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Ceres Correctional Prison

SOLARZONE:  50,000 kL Solar system with  720 m2 Array of Flat Plate Solar Collectors

TOTAL M2 Panels 720
Tank Storage 50,000
Year Commissioned 2012
Tank Construction Black Metal
High / Low- Pressure Storage High Pressure
Litre / m2 69
Energy Savings / Annum kWh 617,580


SOLARZONE (Pty) Ltd is a company based in Cape Town, which specializes in planning and selling of high quality solar water heating and photovoltaic systems (solar electric). SOLARZONE (Pty) Ltd was established in 2006.
The vision of SOLARZONE is to establish partnerships with companies from a wide variety of business sectors in Southern Africa in order to realize solar projects together. Our target market is very wide, but the main focus is large scale applications in the commercial, industrial and hospitality sector. The focus is to supply solar installations to hotels, schools, hospitals, stadiums, residential buildings and housing developments.
The clients are trained by us to install and maintain our products. We intend to work very closely together with local government on realizing key projects. SOLARZONE (Pty) Ltd aims to supply the whole range of solar systems, but also to increase and to transfer the knowledge of solar energy and its benefits to all people in Southern Africa.



As a subcontractor of Vusela Construction, SOLARZONE and Vortex Plumbing completed after 4 years total construction time the last Phase of the SWH System in 2013. The company specialises in integrated energy strategies for large scale, commercial solar water heating and photovoltaic systems.

The 720m² of flat collectors are split in three systems:

  • Block E with 144m², 10000 Liter Storage
  • Block F with 288m², 20,000 Liter Storage
  • Block A with 288m², 20,000 Liter Storage

All systems are similar in design and concept. The systems make use of the PAW Solar Kaskade heat transfer system. In theory it is heat exchanger connected in parallel with variable speed drive pumps fitted on each side of it. All systems have a heat pump backup, the system at Block A, has additional an instant water heater backup as well.
All collectors are connected in banks of 6 serial and then parallel. The system is filled with a glycol mix to protect it against frost. The tanks in the system will be heated up indirect through to the heat exchangers. Through to the external heat exchangers banks which working in master slave combination and with variable speed pumps, continuous the water is warmed and distributed to the banks of tanks.
The Solar Kaskades is also fitted with water flow meters and temperature sensors. The VSD (Variable Speed Drive) pump speeds on both sides of the heat exchanger is constantly adjusted to maximise the solar energy input and to ensure that a minimum temp 50°C is send back to the tanks. All this is done by the Resol Deltasol E controller and a VSD (Variable Speed Drive) relay box. The 72 panel system has 2 x solar Kaskade heat transfer stations and the 144 panel system has 3 each.
The solar panels banks are broken up into banks of 24. A full Tichelmann configuration was designed to ensure that every panel in every bank gets the same amount of flow. We have installed flow adjusters on the inlet of each 24 panel bank, but none of them had to be adjusted, they all had similar flow.



A very nice design and the first of its kind in South Africa for a correctional facility. The more government owned facilities are fitted with renewable energy technologies the better for the economy. A very good benchmark system of what can be done.



Tel: 021-813 6680


Unit 6a, Erica Way · Somerset Business Park

Cape Town 7130, South Africa





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