Electricity and Control June 2025

Renewable energy + industrial sustainability

The cost impact of tracking options in PV power plants Solar photovoltaic (PV) systems have a significant role to play in increasing the power generation capacity in South Africa. However, the PV power generation profile used in South Africa’s recent long-term planning simulations does not accurately represent the current and expected future PV power generation in the country. This is the view of Shaniel Lakhoo, Senior Electronic Engineer for WSP in Africa.

Shaniel Lakhoo, WSP in Africa.

A s South Africa progresses its energy transition, Eskom is predicting that solar PV’s contribution to generation capacity will grow to 19% by 2030. it is clear that solar energy will play an important role in the country’s future power generation. Understanding the power production profile for PV plants is critical in ensuring the right decisions are made on the generation technology mix to best meet the country’s electricity demand. Deploying the right mix is key to providing a stable, lowest cost electricity solution. One of the critical factors to consider in utility-scale PV plant centres on how the modules are set up on the site and whether the modules are fixed in place and angled to compensate for the latitude (fixed-tilt) or track the sun during the day on a single horizonal axis (single-axis tracking). The choice has significant implications for cost-e”ectiveness, energy output and, in turn, influences when and how much power may be injected into the grid. Accurate PV power generation profiles The accuracy of PV power generation profiles is crucial for long term power generation capacity expansion planning. These profiles inform the broader energy mix and capacity planning for the future. The country’s studies, included in the Integrated Resource Plan (IRP) 2019, show the predominant use of fixed-tilt systems with the IRP 2023 not providing su”icient information to conclude the profile used. This is despite the growing use of single-axis trackers in real-world projects. Single-axis trackers, which follow the sun’s path through the day, generally outperform fixed-tilt systems in terms of energy production. In my research, I found energy gains of 12.9% to 20.1% could be achieved annually, by using single-axis tracking

systems as opposed to fixed-tilt systems. By analysing the Levelised Cost of Energy (LCOE) – a measure of the average net present cost of electricity generation for a plant over its lifetime – I sought in my research to determine which configuration would o”er the lowest LCOE. Across all scenarios and locations, single-axis trackers consistently emerged as the most cost-e”ective solution. Despite the higher upfront costs, the energy gains from using trackers more than o”sets these expenses. This results in a lower LCOE compared to fixed-tilt systems. Further sensitivity analysis, to understand the most significant factors impacting LCOE, showed that the balance of system (BOS) costs and the ground coverage ratio (GCR) are the most critical variables. Interestingly, the cost of land had only a minor influence on LCOE. This was true even with the upper band equivalent to more than four times the profits that could be expected from using the land for agricultural purposes. I also explored bifacial modules in the analysis as these are becoming more prevalent in the market and are being deployed in new projects. However, through my simulations I found that the additional energy produced by bifacial modules does not justify the 6% premium over single axis trackers. Compared to fixed tilt systems, the added energy was su”icient to make this the lower LCOE solution. These insights are of value for decision makers. The analysis showed that even in scenarios with lower GHI (Global Horizontal Irradiance), single-axis trackers with mono-facial modules remained the most cost-e”ective choice. Additionally, the plant design can be optimised based on GCR, knowing the cost of land is not a significant factor, and so improving the overall feasibility of solar projects.

Among the critical factors that influence power generation capacity and cost effectiveness in utility-scale PV plant centres on how the modules are set up on the site and the use of fixed tilt or single-axis tracking modules.

12 Electricity + Control JUNE 2025