Solar power out of the opencast mine: RWE relies on Ormazabal switching stations for grid connection

Our long-standing partner RWE is driving forward the expansion of solar energy and is focussing on innovative solutions. The combination of solar modules and battery storage systems, which act as a buffer between solar power generation and the supply grid, is not the only innovative aspect of these solutions. The location is also special: the utility operates a ground-mounted photovoltaic system with integrated storage at the Garzweiler opencast mine near Jackerath in Germany. An agri-PV demonstration plant has also been built here. Three different PV concepts are being tested on a recultivated area. RWE is also building several photovoltaic systems in the Hambach opencast mine, which is also located in the West of Germany. RWE is using customised switching stations from Ormazabal to connect the solar parks to the medium-voltage grid.

The Jackerath photovoltaic storage plant is one of the projects that RWE has realised on its way to climate neutrality. As part of the project, a total of 22,490 solar modules were installed on an area of around 10 hectares in the Garzweiler opencast lignite mine. The electricity generated here from solar energy is fed into the grid and is calculated to supply around 4,000 households. A battery storage system with a capacity of 8.1 MWh is also integrated, and is designed for a two-hour power consumption and output. This means that the electricity generated can also be utilised after sunset and used as required.

“Solar power in combination with a battery storage system from the opencast mine is a successful model. Not only the recultivated areas around the opencast mine, but also the active opencast mining areas offer plenty of space for renewables. We have proven this with the Jackerath photovoltaic storage system”

says Benjamin Dolle, Solar Project Manager at RWE Renewables Europe & Australia.

Reliable delivery of the station

For the connection to the medium-voltage grid, a distribution and metering station with switchgear was required, which gathers the individual supply lines of the various PV parks and provides a common connection point at the substation. We were awarded the contract for the corresponding tender by RWE and were able to meet an early deadline despite ongoing supply difficulties on the market and offer a competitive price.

“Only one year has passed between the tender in summer 2022 and the delivery of the station in September 2023. Given the current delivery times for individual components as well as concrete and station buildings, this is a pleasing result”

says Thomas Höfkens from the Ormazabal Solutions Team Germany.

cgm.800 fulfils all requirements regarding technical details

We fully met the technical requirements and our Ormazabal Solutions team developed a customised energy distribution solution for the solar park. The substation was manufactured by Scheidt as a multi-room solution and has a further area for communication technology in addition to the system room. A medium-voltage switchgear of our cgm.800 product type is used. It consists of 5 cubicles and has an operating voltage of 25 kV. It is suitable for higher rated currents of up to 800 amperes and enables, among other things, the realisation of measurements in compliance with the utility by accommodating the certified current and voltage transformers. Both are installed in the cable connection compartment of the circuit-breaker outgoing feeders. This allowed us to avoid the need for additional measuring panels for each outgoing circuit breaker, saving both space and financial resources. For the station’s own power supply, the complete solution also includes a supply transformer (160 kVA). Ormazabal also designed the auxiliary technology in accordance with RWE’s requirements. We relied on the Sigma F + E 2.0 for short-circuit and earth fault detection.

Challenges at the installation site in opencast mine successfully mastered

The delivery of the 50-tonne station initially proved to be complicated due to the hard-to-access installation site in the middle of the opencast mine. In addition, there was only limited space available for the 200-tonne crane, as there is an overhead power line nearby. However, thanks to good coordination between our team and RWE throughout the project, challenges such as these were successfully overcome and the process, including the installation, ran smoothly.

“The cooperation was good and very straightforward. We were able to find solutions to any difficulties that arose at short notice. For example, with the procurement of cable connectors that are compatible with the pre-assembled connection cables of the voltage transformers. Ormazabal was able to achieve significantly faster delivery times here.” 

Michael Demming, Electrical Engineer at RWE Renewables Europe & Australia.

Switchgear cpg.0 for the grid connection of solar parks in the Hambach opencast mine

We were also commissioned to supply a customised MV switchgear for the grid connection of the PV parks in the Hambach opencast mine. RWE is building several photovoltaic systems on the future banks of the planned Hambach opencast mining lake. Until the lake has reached its final filling level, there will be several years to temporarily utilise the area for the solar parks. One of these is the “RWE Neuland Solarpark”. The solar plant of this project provides a peak electrical output of 12 MWp and the connected battery storage system is designed for a two-hour power consumption or output. It has a capacity of 8.1 MWh.

The RWE decision-makers decided in favour of the cpg.0 switchgear with an operating voltage of 30 kV, which has 2 feed-in cubicles, 3 outgoing cubicles and one auxiliary cubicle. For this project, too, a transformer for own consumption (100 kVA) and the Sigma R+D 2.0 are used. The cpg.0 fulfils the same function here as in the Jackerath opencast mine, which is to gather the energy generated in the PV parks and realise the utilities measurements. The company Kalchschmid supplied two stations for the project: one for the medium voltage and one for the communication technology. The installation finally took place on site in the opencast mine. Here too, the installation of the stations was successfully completed as a team, despite difficult conditions such as bad weather and restricted access.

Ormazabal technology also incorporated in SMA power stations

To ensure that the solar power in Hambach can be reliably fed into the grid, the German specialist for photovoltaic system technology and energy solutions, SMA, supplied four Medium Voltage Power Station 5500 (MVPS). These consist of a robust central inverter and matched medium-voltage components. Ormazabal technology is also used here. The power stations are equipped with Ormazabal cgm.3 switch panels and ekor.rpa protection technology.

The realisation of the projects in Hambach and Jackerath illustrate the common goal pursued by RWE and Ormazabal: to achieve progress in the use of renewable energy. The projects are proof of the effectiveness of partnership-based cooperation and the joint commitment to a more sustainable future.