- PV park with impressive size of 125 MWp
- The largest PV park in Bavaria to involve public participation and one of the largest in Germany
- Around one third of the PV park is owned by citizens
- Citizens can actively participate in the project via an energy cooperative
- Joint promotion of the local energy transition through citizen participation
- Goals: Generation of solar power for self-supply, provision of heat for households and businesses in the region and charging stations for electric vehicles
- Measures contribute to independence from fossil fuels
- Local energy transistion is driven forward through various approaches
Bundorf, a municipality in the district of Hassberge in the Lower Franconia region of Bavaria, Germany, is in one of the regions with particularly low precipitation and long dry periods. This poses a growing challenge for the agricultural use of arable land. The region is therefore classified as one of the "disadvantaged areas". This means that the agricultural land can only produce low yields or is difficult to use due to factors such as soil quality or topographical conditions (e.g. slopes). In Germany, this affects about 50 percent of agricultural land.
In response, the local community pursued a whole new approach and, within just a short space of time, launched a flagship energy transition project. In 2020, the idea for the largest citizen solar park in open space to date was born in Bundorf. In October 2022, construction began in two sections, including an electrical substation, on a total area of 125 hectares. The facility was commissioned on September, 2023.
A showcase project for a comprehensive energy transition
- Citizen participation concept via te energy cooperative EGIS eG
- The region benefits from a connected district heating network and a charging infrastructure for e-mobility
- The project was palnned in harmony with nature, which enables the protection of nature, environment and species
- The PV park helpts to counteract the direct effects of climate change. The PV modules provide shade and thus also protect the soil from drying out.
The cooperative collaboration of all those parties involved is particularly commendable. From the mayor and municipal representatives to the project developers, operators, tenants and the residents of Bundorf - everyone pulled together from the very beginning. The land was made available by various tenants. Less than two years passed from the first project sketch to implementation. All the necessary permits were granted within a year and a total of 85 million euros was invested.
In purely mathematical terms, the 125 MWp project could generate enough electricity to supply 37,500 households with power. However, the small town of Bundorf, with its population of about 884, has nowhere near that many households. Therefore, the neighbouring towns of Bad Königshofen, Haßfurt and Schweinfurt also get to benefit from the solar power generated there.
The energy is fed into Bayernwerk´s grid. The grid operator also laid the AC cables and was responsible for building a series of medium-voltage transformer stations on the construction sites. These are routed to a central transmission station on the PV field. In addition, a feed-in substation was built at the point where the electricity is fed into the grid. A special counting concept via switch panels is used at the substation to count the electricity separately. The feed-in takes place at a voltage level of 110 kV.
E-charging infrastructure - environmentally friendly driving
In Bundorf, the promotion of e-mobility is also an integral part of the concept. Active work is currently underway to expand the charging infrastructure for electric vehicles in and around Bundorf. A total of twelve charging stations will be available to provide electric vehicles with the environmentally friendly electricity from the PV park.
Bundorf district heating network - from electricity to heat
In addition to the solar park, an emission-free district heating network was installed
- A district heating station with a capacity of 150 kilowatt was installed
- Conducts the heat from the pipe network to the buildings as required (including public buildings such as the community center and kindergarten)
- Large hot water storage tank (buffer tank) ensures sufficient heat is in the winter months and in times of low solar radiation
- 200-kilowatt woodchip boiler for additional security in the winter month is available
- Boiler covers a maximum peak load of 1,600 hours
As the general contractor, we are taking responsibility for the planning, implementation as well as maintenance and service of the district heating network. EGIS eG will act as the operator of the district heating network.
MaxSolar as an Independent Power Producer (IPP)
Part of the ground-mounted PV system is operated by MaxSolar as an independent power producer (IPP). The electricity generated is marketed through a so-called Power Purchase Agreement (PPA). This type of marketing of renewable energy is now widespread in Germany. Here, electricity supply contracts are concluded directly with the electricity consumer for a fixed period of time. This enables additional income compared to feeding electricity into the public grid.
EGIS eG as an energy cooperative
The citizens' solar park and the district heating network are operated by EGIS eG, which wants to offer the citizens in Bundorf its own electricity and charging service tariff. In addition, citizens, municipalities, associations, foundations and companies have the opportunity to aquire shares in the cooperative. A cooperative share has a value of 150 euros plus a surcharge of 5 euros. The purchase of cooperative shares is currently limited to 4,300 shares per member, which corresponds to a total sum of 645,000 euros.
However, membership in the energy cooperative is not limited to the PV project in Bundorf, but includes 20 energy transition projects throughout Germany. Members receive an annual dividend of currently 6 percent.
Open-space PV parks are often criticized for contribution to the sealing of land. In Bundorf, however, the exact opposite is the case:
- PV open spaces as compensation areas to enhance low-yield soils
- PV modules provide shade and protect the soil from drying out, especially in times of persistently low rainfall
- Part of the area is used for nature conservation and the preservation of biodiversity, e.g. in the form of rough pastures
The measures are described in more detail in the following section.
Studies have shown that not only the species richness of the grassland seed used has a positive effect on pollinating insects, but also the selection of regionally native main species and the ratio of grass and herb seed.
The mixtures used here at the Bundorf solar park create near-natural conditions above and below ground, so that the entire system, from the soil organisms to insects and birds, benefits from the provision of food, protection and habitat.
The fences around the solar park are installed with a ground clearance of 20 cm. This allows all small and medium-sized mammals such as mice, hares and foxes to run freely through the park and find habitat and food there. A wide wildlife corridor connects the forest in the north with the forest island in the solar park.
Ground hollows were already created during the construction work. These shallowly excavated, temporarily wet or dammed areas create small-scale variations in the prevailing conditions. Various plant and animal species can develop in the resulting wet hollows. They increase structural diversity and improve the local food supply.
The planning of the park provides for grove islands, hedges and trees along the fence. They provide birds, amphibians, insects and mammals shelter, food and nesting opportunities. The woody plantings not only create visually and structurally soft transitions, but also provide shade and cool the surroundings through evaporation. This cooling effect is still measurable up to 20 metres away with a two-metre high hedge. Soil covered by shrubs, hedges and fruit trees promotes both humus build-up and groundwater recharge as well as resistance to drought and erosion.
In this way, the PV park contributes to the preservation of natural habitats and strengthens biodiversity in the region.
The first outstanding successes have already been recorded: The population of the skylark, which is particularly protected in Germany, has recently increased significantly in the PV Park. This small songbird and ground-breeder prefers open landscapes as its habitat. It seems to feel particularly at home in Bundorf - from January to the end of July, its songs can be heard between PV modules until the evening. The first results of the skylark monitoring are now available: The skylark population has already tripled. This is a great result.
In addition, it is helpful to know that the Bundesverband Neue Energiewirtschaft (bne) offers a checklist called "Good Planning" to optimally integrate PV ground-mounted systems into the landscape. In this way, the association supports the positive contribution of ground-mounted PV systems to climate protection, species conservation, nature conservation and rural development. MaxSolar was one of the first companies to sign this voluntary commitment.
An ornithological survey was carried out at the Bundorf solar park in 2023, which delivered very good results in terms of the ecological balance.
- Using modern methods, 100 territories of 7 saP-relevant bird species were identified, with the skylark territories along the wildlife corridor standing out in particular.
- With an impressive settlement density of 0.55 and 0.66 territories per hectare in the construction sections BA1 and BA2, the solar park is actively contributing to the protection of native birdlife.
- The number of breeding pairs has more than doubled over the entire area surveyed since the start of construction.
- The high proportion of raw soil in 2023, due to rainy weather and the absence of agricultural pesticides, supports this positive development.
- Skylarks immediately settle in the ground-mounted photovoltaic systems and the density of territories even increases.
- Sufficient warmth due to wide row spacing and sun strips as well as a greater food supply due to extensive cultivation and care have a significant influence on settlement.
The solar park in Bundorf has shown what the "Good Planning" criteria from the Bundesverband Neue Energiewirtschaft e.V. (bne) can achieve in practice. It is not only a sustainable source of energy, but also a protected area for local bird diversity. The extensive and biodiversity-promoting construction methods have created new retreats for endangered species.
- The Bundorf solar park is a great example of a citizen-oriented energy transition that is in harmony with nature conservation goals.
- It illustrates the added value of energy transition projects for structurally weak regions, which can benefit from regional value creation and thus become more attractive.
- Such projects are urgently needed to promote climate protection, biodiversity, environmental protection, nature conservation and rural development.
