CLEANER MOBILITY

HARNESSING SOLAR HEAT FOR MAXIMUM EFFICIENCY

A SANEDI PERSPECTIVE

Over 80% of electricity generated in the SADC region is from coal. However, SADC faces a power deficit due to lack of investment in the power infrastructure leading to subsequent imminent disruption to power supplies, which is a major threat to the economic growth, according to SANEDI, which is constantly abreast of developments within renewable energy.

A considerable share (40–50%) of

electricity is used for hot water

preparation, thus solar water

heating is an important option to

consider in order to reduce the

electricity demand and associated

environmental effects such as CO 2 emissions caused by fossil fuel power

plants. SADC member states have excellent solar irradiation of more than 2000 kWh/m² annual radiation. Estimates from the International Energy Agency (IEA) suggest that solar thermal systems could meet about 70–80% of the regions’ lowtemperature heating and cooling demand. What needs to be done to

harness this energy that can alleviate stress on the constrained electricity grid in South Africa?

Solar energy is available for harness in two forms – heat and light; it may be free, but it requires technology to be able to exploit this valuable resource. The direct use of the heat component of solar energy is extremely efficient since in excess of 90% of this energy can be used directly in a solar thermal technology system. deliver within required parameters, then skills must be developed in order to build and maintain these systems. As technology familiarity and uptake increases a local industry may begin developing in stages to manufacture and support the solar thermal system requirements. However, in parallel to this, quality and standards across all of these areas of technology development must be ensured so that reputation and thus support of solar thermal is maintained.

Various technologies are available for deployment in this sector and South Africa is showcasing some of the best. If widespread uptake and implementation of this technology can be stimulated, a local market will begin to grow. Local market development may have many facets that will grow and be stimulated at different rates when taking nationwide support of solar water heating technology into consideration. Initially, systems need to be demonstrated to be able to South Africa has already made significant progress in the above described value chain, stopping just short of manufacturing, the implementation of solar thermal technology is steadily increasing and innovating. South Africa is now rated in the top 20 of District and Residential Heating Global Capacity (IEA 2019) based on significant installations at Wits Junction student residences and the Klein Karoo International Ostrich Leather Tannery.

Projects raise SA’s solar thermal ranking

In 2019 South Africa leapt from relative obscurity into the global top 20 of solar thermal installations in terms of m 2 collector area as a result of two of the largest sub-Saharan solar systems – in Johannesburg and in Oudtshoorn in the Western Cape. These SOLTRAIN projects, a district heating plant for Wits University residences and a solar process heat plant for the Klein Karoo International (KKI) Tannery, will save millions in energy costs over the lifetime of the plants. Since the system was commissioned, complaints of not having hot water have reduced by 98%. The estimated cost savings are R40 million over the next 20 years, and the University had seen substantial electricity savings over the eight-month trial period. The thermal energy is free and the centralised plant requires a lot less maintenance intervention, thus reducing costs.

Klein Karoo tannery

The KKI tannery section has installed a 600 m 2

solar collector system to reduce costs and increase competitiveness, and to move its production to a more renewable base.

Wits Junction The Wits Junction district heating project combines solar, co-generation and gas heating technologies, servicing

Stellenbosch University had approached the tannery for process heat application viabilities and it agreed to contribute to the study. The process heat infrastructure

14 student residence buildings with hot water from

one centralised hot water plant room. The installation

includes 600 m 2 solar heating plant with 10 m 2 Austrian

collectors.

The Junction houses 1 103 students, with an average consumption of 94 000 litres of hot water per day. Peak demand is in the morning, averaging 30% of daily consumption, with a maximum demand of 28 200 litres in an hour. The system supplies the entire hot water demand, including kitchens, laundry, cleaning and other domestic uses.

is an oil burner and the feasibility study design entailed solar displacing the local fuel, indicated as 60% solar fraction. The fuel source is LO10 paraffin oil, at an indicated rate of 11.8 kWh per litre. The savings, based on measurements from the plant, indicate 285 000 kWh, with an average indication of or 24 150 litres of oil for eight months. The university predicted a payback of 6.5 years based on a financial model analysis from the feasibility study, which includes maintenance, finance costs and all system related expenses.