Smart Solutions

CéléWatt – a Solar Park on Trees

Small-scale, community-owned solar energy parks using locally sourced timber to support the photovoltaic panels.

Implemented inCarayac, Lot, Occitany

Country : France

What’s the solution?

A community solar park occupying less than one hectare of land to allow energy production at village scale. It is halfway between an individual installation and a ground-based power plant.

Solar panels are installed on a raw-wood structure sustainably sourced from surrounding woods. The solar park does not require the construction of a technical building and does not generate any nuisance (no noise, odour or radiation).

The governance of the solar park is community based and citizen-led, combining crowdfunding with cooperative management.

Whilst it requires a reasonable initial investment (around €220,000), it delivers long-term savings with regards to energy costs.

What makes it smart?

The smart dimensions of a community solar park built on local trees are numerous. It demonstrates an effective small-scale solution for delivering renewable energy for the benefit of the local community, including long-term cost savings, reduced pollution and a contribution to the international effort against climate change.

It is also possible to combine the solar park with local biodiversity initiatives – such as using sheep to restore grassland within the solar park territory.

The project can be seen as innovating in three ways:

Social innovation: Its governance system is community based and citizen-led, combining crowdfunding with cooperative management. Furthermore, by producing electricity equivalent to their electricity usage, residents are encouraged to think about their lifestyle and look for ways to save energy

Technological innovation: It is a unique example of a solar plant constructed on untreated and unprocessed wooden supports

Business innovation: By using short supply chains (local timber) and depending on local people, both the costs and the solar park’s ecological footprint are minimised.

“Replacing the galvanised steel supports of the solar park with raw wood collected in the neighbourhood drastically improves our ecological footprint and adds a local dimension to the project,” explains Bertrand Delpeuch, the cooperative chairperson.

The building of the solar park involves local professional teams from different sectors: land management, renewable energy engineering, legal services and communication. It inspires new ways of working, combining pro bono expertise of the cooperative members with skills from local professional teams.

How is the solution implemented?

  • The first step in implementation is to carry out a geotechnical study of any proposed site. Several conditions must be met in order to find a suitable location:
  • The plot of land must be well oriented for the sun; be close to an electricity line in order to limit the cost of connection to the network; and have easy access for installation work.
  • The plot can be owned either privately or by the municipality (this is the option favoured by the CéléWatt example presented below).
  • An environmental analysis must be carried out to ensure that a park can be set up without harming the ecological value of the site.
  • There must be agreement from the Municipal Council to launch the necessary studies and from the Government service (through the local ‘Prefecture’ and the Regional Nature Park) to carry out the work.
  • A small solar park (maximum 250 kWp - kilowatt peak power) requires planning permission. Government services give the authorisation after checking that the project is compatible with existing land management schemes. Once the site and the permits are acquired the implementation steps are as follows:
  • Site preparation (clearing, securing, access);
  • Source timber;
  • Land survey;
  • Legal services;
  • Construct solar panel supports;
  • Engineering for the installation of panels;
  • Maintenance;
  • Media, communication and press relations.

In what local context has it been applied?

The unspoiled, authentic nature of the Célé valley is a key feature of the area. Its preserved environment is a unique selling point for ecotourism and organic farming. As with many remote rural areas in France, its population is slowly increasing in the last 20 years, as young eco-friendly families and retired people move into the area.

“Our original idea was to promote local employment and natural resources,” says Delpeuch. “As we had no room to manoeuvre on the origin of our solar panels, which are delivered to us from China by the company Talesun, we decided to focus on the poles.”

The area is indeed rich in oak forests. This straight and solid wood, about 15cm in diameter, is traditionally used as a support (‘bouchot’ in French) in mussel farming in the nearby county of Charente-Maritime. “Replacing the galvanised steel supports of the solar park with raw wood from forests about 30km from here improves our environmental performance,” Delpeuch explains.

Who was behind the implementation?

The launch and creation of the community solar park was managed by a group of a dozen volunteers living in the area that became administrators of the CéléWatt cooperative. The creative brain behind it is CéléWatt chairperson Bertrand Delpeuch, a retiree and agronomist by training. He has managed several programmes within the European Commission, including Life-Nature and Comenius. Engaged in local civil society activities, he brings to the project his ability to inspire and network. “When we started to imagine these solar parks, there were only five of us,” he says. “We wanted to tackle the energy issue, to become more resilient and self-sufficient at village level along the Célé valley.”

CéléWatt is a public interest cooperative society (in French: Société Coopérative d'Intérêt Collectif - Scic SAS) that helps generating community power. It brings together volunteers willing to engage in a local, ecological and citizen led project in the Célé valley. CéléWatt has 480 individual members as of October 2020 of which two third are local people.

The objective of the cooperative is to produce and sell:

• Energy from solar and other renewable sources;

• Services for the substitution of nuclear and fossil fuels by renewable energy;

• Services for the reduction of energy consumption.

What was the local journey?

Inspired by several experiments, notably in the Gard and Aude regions, CéléWatt developed its first solar park in 2018, in Brengues (South West France) in cooperation with the PV company Mecojit. The plan is to develop a cluster of citizen-owned solar parks along the valley of the Célé river.

In May 2017, a first plot was chosen in Brengues, the connection with power operators was made and the call for subscriptions was launched. During winter 2017-2018, volunteers helped to clear the site and fence the area. The engineering company took three months to build the park that was officially inaugurated in June 2018.

The second solar park in Carayac is the first in Europe mounted on untreated wood (Quercus pubescens). The lease was signed with the municipality at the beginning of 2020. The prior declaration of works was filed in March and validated by the authorities at the end of April.

In June 2020, the purchase contract for the production of electricity was signed with Enercoop, a renewable energy utility operating at national level.

The staking of the panel connection points was carried out at the end of June. Tests of the new wooden supports, designed by Mécojit, took place in July. Two local companies installed the fences and earthworks necessary for accessing the park. A 60 m³ flexible tank was also installed at the request of the Departmental Fire and Rescue Service.

The oak trees for the panel frames were cut down during September and brought to the site for assembly in October. This wood was chosen because it is indigenous and is very weather resistant. Although there is a minimal risk of the timber being infected by a fungus, sections can be easily replaced. Each timber frame is attached to a steel mounting bracket which acts as a foot to prevent the wood touching the ground. The stability of the panels will be visually checked every three years and a general overhaul will be carried out during the ten-year maintenance.

What have been the main outputs & results?

  • The park in Carayac has a capacity of 250 kWp (maximum energy intensity) for an average annual production of 320 000 kWh, or the average consumption of 220 inhabitants. All the electricity generated is sold to Enercoop.
  • Main benefits are:
  • Energy efficiency, with 0.08€/W buyback tariff secured by Enercoop;
  • Short supply chain for oak wood used to support solar panels on the second solar farm.

What does it bring the village/community?

  • CéléWatt has a strong commitment to community-led development. The Carayac solar park is a community-owned solar park providing:
  • Long-term energy savings and reduced cost of living;
  • Local jobs (10 local companies have been involved in the process);
  • Personal savings invested and managed locally by a cooperative society, known and open to all.

What’s needed

Financial resources

Main types of cost:

The main costs associated with constructing the Carayac solar park include:

• Rental of the municipal plot (3 200 m2)

• Acacia stakes, sheep fencing 1.60 m

• 746 Talesun monocrystalline silicon panels, 335 Wp each

• 5 Kaco inverters

• Oak support structures for the panels

All the running costs – coordination and administration – are delivered pro bono by the cooperative team of local retirees.

Financial needs:

• Initial/set-up costs: € 220 000

• Ongoing/recurring annual costs: € 17 000 (for the whole cooperative)

• The daily management is done pro bono

Funding received:
Crowdfunding campaign237,000 €There is no public funding of the Carayac project. All of the money stems from the cooperative’s share capital created through a crowdfunding campaign launched in 2017.

Human resources

All in all, around 30 people have been directly involved, either pro bono or through conventional working arrangements covering land management, renewable energy engineering, legal services and communications tasks.

Physical resources

You need a plot of south-facing land (less than 1 ha) that is not too far from a medium-voltage electric line.

Solar panels are monocrystalline silicon panels for better energy efficiency. Each panel generates 335 Wp.

The panels are mounted on locally sourced timber derived from around 600 young oak trees (which were about 15cm in diameter).

What to do…

  • Trust the capacity, expertise and willingness to help of the local community, even pro bono.
  • While designing the project, try to minimise the risks.
  • Carefully check the fast moving legal framework in your region/country, especially in terms of company status, crowdfunding mechanisms and participatory finance.

and not to do

  • Don’t wait for higher levels of local government to support your initiative at the start, simply rely on citizens and the local community.
  • Don’t rely on militant support only: your advocacy messages should reach out to the local community as a whole, not just the usual suspects.

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