SA’s largest rooftop PV installation generates 120MWh on average during summer months

Submitted by: Abigail Knox, Thursday, April 17, 2014

<p>Arial view of Belgotex 1MW Solar PV Rooftop installation. (Source: Belgotex)</p>

Arial view of Belgotex 1MW Solar PV Rooftop installation. (Source: Belgotex)

Recognising the trend of ever increasing electricity prices, Belgotex in Pietermaritzburg made the decision to build a 1MWp solar plant on part of the 100 000m2 roof of their manufacturing facility at a cost of R17 million as part of their strategy to offset 5% of their monthly electricity costs.

Cape-based engineering, procurement and construction company, Sustainable Power Solutions delivered on the brief by Belgotex to design, procure and project manage the installation of an emission-curbing, cost-saving solution. Sustainable Power Solutions was also responsible for the 710 kWp solar power installation at the Dube TradePort in KwaZulu-Natal.

The 1MWp plant is expected to generate 1,415 MWh of electricity per year; this is approximately 5% of the electricity that Belgotex requires for the production process in their factory. By saving on 1,415MWh of coal-based electricity from national grid, Belgotex can expect to reduce their carbon emissions by 1,386 tonnes per year.

Since installation, “the plant has generated an average of 120 MWh per month despite the overcast and cloudy conditions we have had this summer,” said Malcolm Naicker of Belgotex. The table below shows the daily production of the Solar PV plant.

 

Belgotex Solar Plant: Performance Ratio Calculation

Month

Irradiation

[kWh/m2]

Calculated Nameplate Yield

[MWh]

Actual Yield

[MWh]

Performance

Ratio

Dec 2013 146.02 146.00 109.95 75.3%
Jan 2014 178.94 178.91 139.12 77.8%
Feb 2014 164.47 164.44 127.92 77.8%

 

“The expected performance ratio for the plant is 77.5%.The plant operated below that ratio in December due to a faulty inverter and has since stayed above 77.5%,” said Axel Scholle, MD of Solar Power Solutions

The Belgotex Electrical Department receive all data readings on the plant’s performance. If there is an error or fault with the system, panels, or inverters, the web-based monitoring system will alert the electrical department. “At the moment it is maintenance free,” said Naicker, “because there is a 1 year guarantee on the workmanship and plant operation with Power Solutions”.

The 1 MW Solar PV plant consists of 4041poly crystalline modules each rated at 245 Watt peak. The solar panels consist of 21 fields with 7 strings in each field, linked to 64 Danfoss three-phase grid inverters. The 400v AC power is stepped up to 11,000V and fed into the Belgotex ring main on the premises.

The solar plant is a complimentary source of energy which operates in conjunction with the electricity grid. During a power failure or load shedding, the solar plant switches off and cannot, on its own, provide power to loads within the Belgotex factory because it does not have any battery storage. Because solar power generation is variable and power consumption is variable, battery storage is required to provide a stable grid.  This is currently economically unfeasible at MW scale said Scholle.

“We are investigating our options for the continued supply of electricity from the Solar PV system when the grid is down,” said Naicker.

Scholle explained that the offsetting of emissions and generation of renewable energy can be guaranteed, by ensuring a high efficiency performance ratio of the plant. However, “due to variations in weather and variable load profiles, we cannot guarantee a reduction in maximum demand charges. However we do expect there to be a reduction and are monitoring this to evaluate the financial impacts,” said Scholle. 

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Abigail Knox