Standard Bank invested in a hybrid solar water heating and heat pump system at the company’s head office in Johannesburg, as it moves to increase energy efficiency and reduce its carbon footprint.
The new R2.3-million system, installed by Kayema Energy Solutions, is expected to save nearly R1-million a year in energy costs, thus a return on investment would be seen in just under 4 years.
The 400-kW hybrid system consists of 100 solar water heater collectors, which will heat about 20 000 l of water, while another 28 000 l of water is heated using energy efficient heat pumps.
It reduces the building’s energy consumption by 5%, and Standard Bank noted that the energy saving was equivalent to powering seven households for a year.
The 100-collector installation, which took about four months to design and install, covers over 200 m2 on the roof of 6 Simmonds street in central Johannesburg. A back-up and top-up system consisting of two heat pumps supports the solar installation for days when the sunshine is not optimal.
The solar collectors were specifically chosen as they make use of a black chrome absorber, which performs better than painted collectors, and ensures a longer life-span of the panels.
There is an ultrasonic weld between the absorber thins and the copper pipes, which allows more efficient heat transfer.
The installation consists of some 700 m of copper piping.
The 4 mm tempered glass used in the panels is hail resistant, and has a low metal content, which also allows for better heat absorbency.
Because of the water consumption profile, the total storage capacity of hot water in the plant room was insufficient to allow for a total solar solution to be installed – the addition of heat pumps ensured capacity was available, while reducing peak electricity load.
The solar collector panels and heat pumps were placed as close to the plant room as possible in order to save on both installation costs for reticulation and heat losses during transfer.
Kayema made use of 40mm lagging to minimize heat loss, and copper piping for reticulation.
A closed loop system with non-toxic glycol solution was used for heat transfer, to protect against system damage by freezing or build up of impurities carried in the potable water.
Installation of system occurred over two stages:
1. Stage One: Preparatory work such as system design, piping, heat exchanger and solar panel stands fabrication.
2. Stage Two: Installation of solar panels, heat pumps, reticulation & components.
Kayema also continues to provide technical support and periodic visits thus ensuring long term benefit from the system regardless of usage, weather conditions, wear and tear etc.
Kayema also ensures a twenty-four hour response time. In the unlikely event that the system requires repairs an electrical back up is automatically activated until the solar system has been repaired.