Initial Situation

Delta Electronics, Inc., a global leader in power and thermal management solutions, was selected to supply its RPI M50A string inverters to the firm InnoSun Energy Holding for the construction of Namibia’s first and largest utility-scale solar PV power plant. InnoSun was a company established in 2008 by InnoVent, a large and well-established French wind developer, with the mission of developing PV projects across Africa. The solar power plant totalling 4.5 MW is built two hours northwest of the city of Windhoek on 16 hectares of arid land.

The project began after the signing of the first-ever Power Purchase Agreement (PPA) between NamPower, Namibia’s national power utility, and InnoSun Energy Holding. After initial site surveys were completed, construction commenced on August 18, 2014.

Project Realisation

The PV plant built near the town of Omaruru in the Erongo Region of Namibia took six months to construct after the contract was signed. Sixty local Namibians were employed and trained for the installation of the PV plant structure. InnoSun chose TSMC CIGS (copper, indium, gallium, selenium) thin-film modules for the plant which were mounted on a horizontal tracking system. The 1-axis tracking system adjusts the solar module position in relationship to the position of the sun over the course of the day thereby maximizing energy output, and increasing output by up to 25% when compared to a fixed-tilt system. A total of 33,418 thin-film solar modules were installed in the system as well as 100 Delta string inverters, providing a corresponding PV power of 4.5 MW.

InnoSun selected the Delta RPI M50A three-phase transformerless models with 50 kVA output because of their reliability and low maintenance. Inverters from Delta are characterized by a robust and reliable design. The housing is made of high quality aluminium covered with a special finish to make the inverter very durable and corrosion-resistant. Due to their rugged design, the RPI series inverters are an ideal choice for the rugged environment of Namibia.

The use of string inverters were preferred over central inverters because the former need less cables and components and can be installed without special housing in protected areas. As a result the investment costs can be reduced. Additionally, the string inverter creates a stable production level. The PV plant can continue to run with very low production losses when one string inverter fails in comparison to much larger losses when a central inverter stops functioning. Because the Delta RPI M50A string inverters require very little maintenance over the years, no maintenance contract is needed, which significantly lowers the operating costs. Now that the Omburu Solar Photovoltaic Park construction is completed, InnoSun is working together with local authorities in order to reach commercial operation of the plant. A commissioning ceremony is scheduled on May 13, 2015.

Conclusion

The 4.5 MW Omburu PV plant has numerous financial and environmental benefits in Namibia. It has already helped the local economy by providing 60 local construction jobs, but in addition will create income from the solar energy produced over the next 25 years. The plant is expected to generate a total of 13,500 MW hours of clean and reliable electricity annually which will cover a large percentage of the energy needs of the region, help maintain stable electricity prices, and avoid power shortages. Furthermore, the PV plant is estimated to help save over 8,500 tons of CO2 per year, the equivalent CO2 produced annually by 1,800 passenger vehicles.

The cooperation with InnoSun was very positive and resulted in a successful implementation of the project. With its inverters, Delta has made an important contribution to the success of the first-ever utility-scale PV project in Namibia and look forward to being part of the growing PV market in Africa. Delta plans to continue to work with InnoSun to provide its high efficiency string inverters for even more large-scale PV projects in this region.