The biggest glazed solar water heating (SWH) installation in South Africa at the moment is in the University of Pretoria and is located on top of the campus carport and rooftops with has a total collector surface area of 672 m2. Three collectors were connected in parallel, and then two parallel strings connected in series resulting in a thermal length of 12 meters. The total capacity of the installation – 430 kWth – could produce 404,700 kWh electricity a year.

One central feeder tube transports the warm water to a building constructed next to the carport to house the heart of the system: two giant 20,000 litre water storage tanks, an expansion tank, membrane expansion vessels (totalling 5,400 litres) and seven external heat exchangers amongst others.

The water heated by the solar panels is stored in the buffer tanks. Through external heat exchangers (that is, exchangers not housed in the tanks themselves), a different continuous fresh-water supply is warmed and distributed to the individual residences.

This results in an indirect loop system, which automatically complies with health standards without having to manage a major maintenance programme, since it will never be used for human consumption. It is, simply, the working fluid of the system.The water is distributed through pump-circulation, via 40 mm diameter heavily insulated pipes. These are mounted on steel frame structures, reaching each residence on campus.

The installation at the university?s veterinary campus(which is my faculty), meets the warm water demands of its new energy efficient residences housing 550 students. It also avoids the production of 450 tons CO2 and saves 600 980 litres of water each year.

This is an innovation that must be emulated by all universities and big institutions in a bid to save our planet from global warming and to conserve water. 

Here are some pictures!