HomeIndustry SectorsEnergy EfficiencyExploring floating solar, a first for Cape Town municipality

Exploring floating solar, a first for Cape Town municipality

The City of Cape Town is the first South African municipality to install a floating solar PV system.

Working with partners Floating Solar, the Water Research Commission and the University of Cape Town, the project is a 12-month research study. Depending on results, the project could potentially inform the design of large utility-scale floating solar PV projects over the next few years through competitive bid processes.

Established at the City’s Kraaifontein Wastewater Treatment Works, it includes a floating solar PV array as well as a ground-mounted PV system to determine evaporation savings and relative energy generation performance of floating solar PV technology.

Phindile Maxiti, City of Cape Town Mayoral Committee member for energy and climate change, say the City has set a target of 300MW of renewable energy by 2030. They want 50MW of this energy to comprise city-owned solar PV plants. “The City has been fighting to move away from the sole reliance on Eskom and to diversify the energy mix for cleaner and more affordable and secure power for all.

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“Given that vacant land in the city is very expensive and rooftop solar PV systems are relatively small, Cape Town aims to explore floating solar PV systems for large scale solar PV installations as part of its pioneering work to diversify the energy mix, to lead by example and to take climate action leaders,” said Maxiti.

The pilot project will look at the amount of energy generated by the floating panels and investigate how much is generated compared to the ground-mounted panels. It will also research the impact the floats have on water evaporation.

“Generating clean power and reducing evaporation rates of water bodies could be a great double-win for sustainability,” said Maxiti.

System specifications

The floating system consists of:

  • A 3.51kWp floating solar PV system: Nine 390 Watt peak (Wp) PV panels mounted on a floating solar island, with panels installed at a 12 degree tilt;
  • Two identical tanks (20m in diameter) including a water supply system: one reservoir is covered by a floating solar PV system and the other reservoir is uncovered as a control;
    The one reservoir is covered using the HYDRELIO AIR technology with a four-per-row configuration;
  • Water levels in each reservoir is being monitored with a float switch. When the water level drops below a predetermined point, a pump will be turned on and water fed back into the reservoir. The volume of water will be measured by a flow meter and recorded; and
  • A three-phase inverter.

The ground-mounted system consists of:

  • Two land-based solar PV systems each with an installed capacity of 3.51kWp: comprising nine 390 Watt peak (Wp) solar PV panels at the same tilt as the floating solar PV system (12 degrees) and nine 390 Watt peak (Wp)solar PV panels installed at the optimal South African tilt of 32 degrees;
  • All instrumentation and equipment required for the experiment (ambient temperature and humidity sensor, pluviometry, solar irradiance sensor, data logger, wind speed and direction sensor); and
  • Instruments installed on the solar PV panels (energy generation monitoring system and temperature sensor).

Floating solar one of many concepts being explored for water security and sustainability

Peter Varndall, the spokesperson for Floating Solar, pointed out that this technology is rapidly becoming a third pillar to the solar PV industry on a global scale. “In following this trend we have identified significant potential within South Africa for this promising technology which as the dual benefit of producing power while reducing evaporation and reserving land for other commercial use.

From the outset we have identified over 60 high potential projects – with a combined capacity of over 450MW – that will be well suited to benefit from Float Solar development. One of the key target markets is the approximately 1,000 water treatment works across South Africa which is well suited to float solar due to significant on-site power demand requiring a sustainable energy source, limited available land and water evaporation savings, as well providing the opportunity to export additional power to the grid,” explained Varndall.

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Theresa Smith
Theresa Smith is a Content Specialist for ESI Africa.

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