Renewable energy specialists, Kea Energy Ltd, have embarked on the construction of a 1.85 MW utility scale solar farm located in the Wairau Valley, Marlborough. Kea Energy have selected the Power Electronics HEMK series of solar inverter platform for the project. After two years of research, design and consenting, construction has commenced with the plant expected to be commissioned in the last quarter of 2020.
The project will use over 5000 individual solar panels and cover 10 acres of land. The panels will be installed on a single axis tracker mounting system. This ensures optimum efficiency of the panel but also prevents shadowing of panels allowing for a higher density of panel installation per square meter. There will also be an added advantage of the panels being bifacial giving the benefit of reflection off the ground.
It is estimated that there is approximately 118 MW of PV generated electricity connected to the grid in New Zealand but the majority of this is low power domestic and commercial systems. The 1.85 MW system being installed Kea Energy will be a first in New Zealand for several reasons, namely:
- It will connect directly to the 11 kV Marlborough Lines Ltd medium voltage network.
- The system utilizes centralized inverter technology which significantly reduces the installation costs.
- It can introduce leading or lagging reactive power (VAR) to assist with network voltage control at a medium voltage level if required. Not only during the daytime but it can assist with voltage stability during the night.
With an install base of thousands of units globally the HEMK solar inverter platform is a well proven platform. The modular design of the HEMK series allows customers to build solar inverters to suit their exact specification. In this case Kea Energy have opted for a 2.25 MVA solar inverter, complete with low to medium voltage transformer, and medium voltage switchgear, all on a skid mounted platform. The HEMK can operate independently as a lone inverter, with several models ranging from 2.125 MVA to 3.8 MVA, or with the introduction of a Power Plant Controller (PPC) can operate with other units of HEMK for higher power applications. Connection at network level can be achieved at 11 kV, 22 kV, or 33 kV. Interconnection to the network company SCADA system is achieved via ethernet directly to the HEMK or PPC.
"The Power Electronics HEMK solar inverter design is very innovative" states Kea Energy managing director, Campbell McMath. "It combines the benefits of a centralized inverter, particularly with regards to the efficiencies of installation cost, and with six field replaceable inverter modules the benefits of a string inverter as well".
To allow maximum flexibility the HEMK series comes "Bus Plus Ready" meaning that it can accept the connection of batteries via the Freemaq DC/DC converter providing a solar-plus-storage system. The Power Electronics NB Electric Vehicle charger can also be connected to a PV field and a storage system through the Freemaq DC/DC to provide a low consumption centralized EV charging system.
The unique skid mounting arrangement of the HEMK series makes for easy installation on either piles or a suitably constructed foundation. Because of its skid mounting design, it can also be easily relocated should the situation require – like the end of a land lease or re-arrangement of the solar array.
Despite the fact this project will include the latest technology to achieve generation there is still an element of "Kiwiana" in the design. Sheep will be used to graze the grass under the solar panels.