Care centre receives large-scale solar water heating system

2nd May 2014 By: Sashnee Moodley - Deputy Editor Polity and Multimedia

Solar energy solutions company Solardura has completed the installation and commissioning of a large-scale solar water heating system for the Blessed Gérard Care Centre in Mandeni, KwaZulu-Natal.

The system will provide 4 000 ℓ/d of solar preheated water for the centre, which serves as a hospice, a clinic and a care centre.

Solardura cofounder Rolf Köstlin tells Engineering News that the installation began at the end of February and the system was commissioned in March.

The system consists of 24 solar flat-plate collectors, covering 61.7 m2; three 2 000 ℓ stratified buffer tanks; a stratified charging module, including controllers with data logger and remote access; and a freshwater module, which includes controllers and ring main feeding.

“Compelled by the rising energy costs and the increasing need for reducing the carbon footprint, the care centre requested Munich-based energy research institute Forschungsgesellschaft für Energiewirtschaft (FfE) to perform an energy audit of the centre in 2013. In its findings, the FfE recommended, among other aspects, a large-scale solar water heating system,” Köstlin reveals.

He adds that, after willing donors had agreed to contribute towards the project, several reputable European solar thermal energy companies were approached. The contract was finally awarded to Austria-based Sonnenkraft, owing to its strong local partnership with Solardura.

The system is expected to yield up to 53.458 MWh a year of energy from the sun, resulting in a large reduction of electricity use when heating water.

A stratified charging module transfers this energy from the collectors to three stratified backup tanks. The charging module determines the energy available in the collectors and at the top and bottom of the tanks. It also optimises the energy transfer accordingly by circulating the hot water either to the top or to the bottom of the backup tanks.

A nontoxic, biodegradable glycol-water mixture is used as heat transfer fluid in the collectors to reduce corrosion and optimise the heat transfer.

Hot water – required in the bathrooms, kitchen, laundry, staff apartments and guest quarters – is prepared by a freshwater module and distributed by three ring main lines, ensuring that the water is always hot at the consumer end points.

The freshwater module heats water instantly on demand by transferring energy from the backup tanks to the freshwater. The freshwater module can heat 225 ℓ of water a minute, which equates to 500 kW of heating power.

The care centre will, therefore, save on costs by reducing its monthly electricity bill. It will also reduce its yearly carbon footprint by an estimated 7 580 kg.

The system’s performance will be monitored remotely by Solardura and Sonnenkraft using a secure Internet connection. Optimisation of the system parameters will also be implemented, where necessary, through this remote connection.