Jaco Botha, managing director of South African power company, Solareff, offers ESI Africa insight into the processes involved in developing a large-scale rooftop solar photovoltaic (PV) project.
Electricity generation through solar PV systems is growing in appeal as an alternative to conventional generation.
The Department of Energy (DOE) has in recent years implemented a successful REIPPP programme,which has resulted in numerous large-scale solar PV systems being built.
These systems require the utility grid to transmit the power generated by them to the point where consumption occurs in the major metros.
Recently the focus of the solar PV market has shifted to embedded generation – which essentially means that the system is built at, or very close to, the point of consumption.
An example of an embedded generator that most readers are familiar with, is a diesel backup generator.
When the embedded generator is from a renewable energy source, the generator is regarded as a primary source where all power generated by the generator is consumed, and in some specific instances, some excess generation is exported to the utility grid.
Benefits of solar PV
Developers of the Gauteng leisure shopping centre Clearwater Mall, Hyprop Investment, became aware of the benefits that solar PV could have for their properties.
Whilst most of their properties are retail shopping malls, which operate seven days per week, they acknowledged the opportunity around the power generated from solar PV systems, which could be fed into the properties’ reticulation and consumption.
It also occurred that the consumption profile of malls, with the primary load being air conditioning and refrigeration, coincides with the generation from solar PV systems.
The simple analogy is that the brighter the sun shines, the greater the need to run air conditioning, which is at the same period when the PV system generates the most power.
Roll out of a rooftop project
Solareff was contracted during August 2014 to construct the first 500kWp system at the Clearwater Mall, Roodepoort. It consisted of 2,000 solar PV modules, supplied by Renesola coupled with Kaco Energy inverters. The system was fully installed and operational during November 2014.
By March 2015, Hyprop was so satisfied with the results attained by the system, that they again contracted Solareff to increase the size of the system to 1.5MWp by adding 1,000kWp. This makes the system at publication hereof, the largest rooftop solar PV system in Africa.
The second phase of 1MWp consisted of 3,948 solar PV modules, supplied by Yingli Green Energy, and coupled to 20 Kaco Energy string inverters of 50kW each.
A general market perception is that the National Energy Regulator of South Africa (NERSA) and utilities, are averse to these type of systems. For this reason applications were brought to NERSA and the City of Johannesburg for this particular system.
Both institutions approved, which shows that the authorities acknowledge the effect that renewable energy has for energy security in the country.
The technical outputs of the Clearwater Mall system in short are the following:
- The system generates on average 2,500,000kWh electricity per annum, equal to the consumption in the same period of 347 average households
- The system generates approximately 10% of the total consumption of Clearwater Mall and all power is consumed by the Mall
- The solution covers an area of approximately 12,000m²
- Saving of 1,530 tonnes of coal per annum
- Reduces carbon dioxide emissions in excess of 2,500 tons per annum
This is a “Grid-Tied” solution, it does not have batteries for energy storage. Whatever power is generated is directly consumed by the Mall.
The first phase of this project took eight weeks and the second phase took 13 weeks to complete, with no major technical difficulties experienced.
Jaco Botha is a Professional Electrical Engineer with years of experience in renewable energy projects. He is a founding member and the Managing Director of Solareff, holding a PMP and GCC qualifications.