REWE Group is a green electricity pioneer in the German food retail sector. We have been supplying our stores exclusively with electricity from renewable sources since 2008. Solar power has great potential, as the roofs of our stores and warehouses offer plenty of space for photovoltaic systems (PV systems). Together with our central energy service provider EHA, we are installing hundreds of such systems on buildings in our group of companies - a major project. Outstanding added value: a large part of the project can be realised independently thanks to the versatile cooperative structure with teams within the REWE Group.
We spoke to people who are working on the solar power project in the REWE Group and EHA divisions involved. They provide insights into the process and cooperation in the supply chain of the PV systems - from procurement to the finished converted store.
In various federal states, solar roofs are mandatory for new commercial buildings. As REWE Group, we go beyond these requirements and also install a large number of PV systems on the roofs of existing properties. After initial trials in 2022, the solar power project quickly proved its worth in the 2023 field test: In the period from the launch in August 2023 to May 2024 alone, we installed a total of 52 PV systems on our stores, plus 7 systems on REWE Group logistics centres.
The installations are prioritised on suitable roof areas at administrative locations, warehouses and REWE, PENNY and toom stores. In principle, all roofs are suitable, provided they fulfil certain structural criteria. This primarily concerns the roof substructure, the roof structure and the roof statics. However, expansion strategy aspects also play an important role. If, for example, demolition, new construction or relocation of the site is planned in the short to medium term, the installation of a PV system does not make economic sense. The systems enable store operators to cover between 15 and 27 per cent of their annual electricity requirements themselves and at the same time make a contribution to climate protection. The green electricity generated is intended exclusively for the sites' own supply, while the cost savings are shared out within the Group. This demonstrates the advantage of the co-operative structure: all locations benefit from solar power - not just those with PV systems on the roof.
Strong partners: REWE Group and EHA
Our subsidiary EHA, based in Hamburg, is a pioneer of the energy transition and a driver of innovation. EHA is our partner in all energy matters - including the supply of green electricity - and supports us in implementing our energy requirements.
Together with EHA, we develop optimal and customised PV solutions for our buildings as a full-service provider. EHA has developed a standardised PV system concept for the implementation of the solar power project. The modular, expandable and scalable system is customised to each individual site.
Behind the complex supply chain of the PV systems is a project team that manages the process hand in hand, from purchasing, transport and storage through to installation. The team consists of colleagues from the REWE Group (procurement and logistics), our own purchasing company in Asia REWE Far East, EHA with its PV team and the logistics service provider Stenkamp. Last but not least, a close exchange with REWE Energy Management is essential, as this is the interface to the store and essential preparations are made for the realisation of a PV system, such as the laying of cables and data cables on the roof.
The speciality: REWE Group purchases almost all PV components directly from the manufacturers, in some cases also via REWE Far East, which is based in Hong Kong. REWE Group purchases around 95 per cent of all components required for a PV system centrally for EHA. As an energy service provider, EHA is responsible for the technical realisation of the projects and operates the systems. The gap between purchasing and technical realisation can also be closed internally. The support provided by our wholesalers guarantees a customised logistics solution from the supplier to the construction site. In this way, we ensure the availability of the required materials.
It all starts with the manufacturer selection
To this end, representatives from REWE Group and EHA meet with various manufacturers of PV systems. The options are then examined, evaluated and selected. Here, EHA benefits from the strengths of the REWE Group, explains Louis Noerenberg, Photovoltaics Project Manager at EHA:
"While we at EHA provide the technical expertise and the exact requirements for the product, REWE Group complements us with its purchasing expertise. The EHA/REWE Group project team can distinguish itself in purchasing discussions with manufacturers in the solar market through high bundled purchase quantities and a professional supply chain. By directly securing annual quantities, we are very fast and cost-effective in the realisation of new builds for PV systems. In addition, REWE Group collects the components itself from the manufacturers ex works and stores them centrally for EHA - a luxury for the selling manufacturers."
One supply chain, many parties involved
REWE Group sources almost all of the components required for the installation of a PV system from Germany, other European countries and Asia. For example, the solar modules are procured directly from the manufacturer in Asia via REWE Group's wholesale organisation. REWE Far East, headquartered in Hong Kong and headed by Daniel Wiest, Division Manager Investment & Consumable Goods, provides support in sourcing and processing. The purchased solar panels are shipped and stored in Germany after their arrival.
"The solar panels travel a long way from eastern China, the world's largest production region, to Germany. Before being shipped by sea container, the panels are inspected on site at the factory. They are then shipped from Shanghai to Rotterdam, which takes around a month. In co-operation with the transport control system, the planned and ongoing goods inwards are tracked," explains Daniel Wiest.
Arrived at destination: Storage in the import warehouse in Voerde
REWE solar warehouse in Voerde (photo credits: EHA)
After being transported by ship, the containers with solar modules are transported by lorry to the central warehouse in Voerde on the Lower Rhine under the direction of our wholesale function, also known as our own business. They are stored there together with other PV components. The warehouse in Voerde, which opened in 2023, acts as an import warehouse for our own business. By utilising existing structures and processes, and in close cooperation with the service provider Stenkamp, the solar business could be seamlessly integrated here.
The installation can begin
EHA calls off the required system components from the warehouse in Voerde 10 days before the start of construction on a site-specific basis. The logistics service provider Stenkamp usually delivers them to the construction site on Monday mornings at the start of construction. If you look at the heterogeneous range of articles, which includes around 25 items such as inverters, cables, wire and substructure parts in addition to the solar panels, the logistical challenges involved in order picking and delivery become clear. The warehouse in Voerde not only enables the construction sites to be supplied with a large number of items from a single source, but also secures bottlenecks in the supply chain through safety stocks. Once the components are available on the construction site, the construction time is usually one week.
EHA experts monitor the operation of the systems
Once the PV systems have been installed, EHA establishes an active monitoring and incident management system and monitors all PV systems using a central monitoring tool. The partnership-based service provider network is central to this. This includes solar installers, electrical partner companies for commissioning, maintenance partner companies and companies for drone flights.
One team - one goal
Anika Schüller, Project Manager Project Management & Strategy, REWE Group, was in charge of coordination between EHA, Purchasing, Stenkamp and REWE Group's own business when the project was launched:
"The solar power project, which has now developed into an entire business segment, is a prime example of how harmonious cooperation within the project team is at least as important for project success as a sophisticated project structure. The result shows that cross-divisional cooperation thrives on thinking outside the box. One team - one goal. That's incredibly productive and a lot of fun."
PV systems on the roofs of stores, warehouses and administrative buildings are an important component of our climate strategy. They complement the consistently sustainable design of our properties, which has been in place since 2008. Together with our PV team, we will continue to supply hundreds of buildings with solar power in the coming years and thus make an important contribution to the energy transition.
one: What is the core task of the EHA PV team?
Simon Meyer: Our core task is to implement PV systems on REWE Group stores and logistics centres. Our team is divided into the areas of construction and operation.
The construction division (stores and logistics centres) is responsible for the process from the acquisition of new sites to the initial design and coordination of the construction and the system design through to implementation.
The Operations division takes over as soon as a PV system has been fully installed on the roof and organises the technical commissioning. This is done on site by an electrical partner company and from the computer (configuration and switching on the system). As soon as this is done, we transfer the systems to our operational management portfolio and begin active monitoring.
We have to manage all the parties involved, draw up contracts and develop guidelines and protocols. This involves a lot of documentation and coordination so that the end result is a high-quality plant. Cooperation with REWE Group's purchasing and logistics departments is central to this.
one: What special features need to be taken into account during construction? What challenges have to be overcome?
Simon Meyer: Every project is individual, which is why the data quality of the construction plans and documents is essential at the start. Another reason why we usually have drone survey flights carried out. If the system is well planned, the next hurdle is the punctual and complete delivery of all PV components. Once the installation partner is also on site on time, we can get started. Some of the challenges are trivial, such as gaining access to the roof or overcoming difficulties with the delivery. Factors such as weather conditions also play a role and can disrupt our schedule.
one: What makes the project so special?
Simon Meyer: A key unique selling point of this project is that we can draw on REWE Group's purchasing and logistics expertise. It buys all the necessary components centrally for us directly from the manufacturers, i.e. we at EHA avoid cost-intensive detours via wholesalers. There is also no risk of running out of components. This is a huge added value in view of the special features of the PV business in recent years. Our solar warehouse in Voerde and the centralised just-in-time delivery of virtually all PV components is the icing on the cake.
one: What are the plans for the future?
Simon Meyer: In 2024, the aim is to achieve the steepest possible learning curve and standardise processes and procedures in order to be able to scale up. 2024 is the basis for all subsequent years, as it is the first year in this constellation with ambitious goals.
☀️ PV systems convert solar energy directly into electricity without emitting climate-impacting CO2. The systems are 100% climate-neutral and therefore contribute to the energy transition.
☀️ A decentralised energy source with which we can produce electricity for our buildings ourselves in an environmentally friendly way and save costs in the process.
☀️ By using it, we are investing in greater independence and a sustainable energy supply.