Solar Panels, Eco-Grazing, and Enhancing Local Biodiversity: A Perfect Synergy.

Overview

SunBuild is building an 11.7 MWp solar field with 10MWh of storage on the former Maisières quarry, near Mons, and will operate and maintain it once it is commissioned. etherra developed the project and owns it. Construction is under way, with commissioning due in [date cible à confirmer].

The 6.6-hectare site lies on Rue Grande in Maisières, between the Portes de Maisières complex and SHAPE. Backfilled with soil from construction sites once quarrying stopped, it gradually turned into a habitat rich in biodiversity — which is why the ecology shaped the design rather than being fitted around it. The Tradecowall landfill permit was finalised in February 2024, and etherra filed a single Class 2 permit with the municipality of Mons in June 2024.

Challenges

Building around what already lives there

The site is not empty ground. Its ponds shelter the protected midwife toad (Alytes obstetricans), and an area of limestone grassland is preserved and kept clear of panels. The permit issued by the Walloon Region sets ecological obligations that shape the layout: twenty ponds for the natterjack toad (Epidalea calamita), three further ponds of 100 m² for the midwife toad, and a new retention basin to manage runoff. Vegetation between and around the rows is maintained by eco-grazing rather than mechanical mowing — quieter, and compatible with the amphibian population the site exists to protect.

Environmental Transition

As required by the permit issued by the Walloon Region, several ecological measures are being implemented to protect local biodiversity: twenty ponds for the natterjack toad (Epidalea calamita) and three further 100 m² ponds designed for the midwife toad (Alytes obstetricans). Runoff water is managed by a new retention basin. The vegetation between and around the rows will be maintained by eco-grazing rather than mechanical mowing.

Solution

The array is ground-mounted, oriented east-west with one meter interrow distance. East-west does not maximise the yield of an individual module — a south-facing layout does that. What it does is fit more capacity onto the same ground and flatten the production curve, spreading output across the morning and the evening instead of concentrating it at midday. On 6.6 hectares hemmed in by protected habitat, that is what makes 11.7 MWp possible on ground a south-facing layout could not have used as fully.

SunBuild's scope runs from engineering, procurement and construction through commissioning, and continues into operation and maintenance once the plant is running. The team that builds the plant is the team that answers for its performance afterwards.

SunBuild is a Belgian EPC contractor for utility-scale solar PV and hybrid PV+BESS plants in Belgium, France and Luxembourg. On Maisières, etherra developed and owns the asset; the engineering, the construction and the long-term maintenance are ours.