French roof crew says dirty solar panels can quietly cut output by 20%—and most owners never notice

A small roofing company in France’s Loire-Atlantique department is betting on a simple idea: solar panels don’t stay efficient on their own. Ramonage et Toit, a local contractor, has carved out a niche cleaning residential photovoltaic arrays—work it says can recover performance that may have slipped by as much as one-fifth over a year without maintenance.

The culprit isn’t complicated. Over time, dust, pollen, bird droppings, and plant debris build up on the panels’ glass surface, creating a film that blocks sunlight from reaching photovoltaic cells. The result is a gradual drop in output that homeowners often don’t spot until they compare production over time.

Industry experts estimate that neglected panels can lose anywhere from 5% to more than 20% of annual performance, depending on the installation’s surroundings and how often it’s cleaned. For a typical home system, that kind of year-after-year shortfall can add up.

From bird droppings to lost power: how buildup drags down production

Among the most troublesome grime, bird droppings are in a category of their own. Unlike ordinary dust, they’re chemically aggressive and can gradually damage certain surfaces if they aren’t removed quickly.

Mixed with fine airborne particles and plant residue, droppings can also create localized shaded spots that disrupt how photovoltaic cells operate—sometimes beyond the exact area that looks dirty.

In most setups, a light cleaning once or twice a year is enough to keep performance near optimal levels. Ramonage et Toit is positioning its service around that regular schedule, using professional methods and—consistent with common industry practice—demineralized water to avoid mineral deposits and streaking as panels dry.

The pitch isn’t only about short-term output. Properly maintained panels can see their usable life extend significantly, with operation possible for more than 25 years. Skipping maintenance, by contrast, can accelerate component aging and lead to repairs that cost far more.

A local maintenance business grows alongside France’s solar buildout

Loire-Atlantique, like the broader Pays de la Loire region, has seen photovoltaic installations increase in recent years, driven by installation incentives and the continuing decline in equipment costs. That growth is creating a parallel demand for maintenance—an area long overshadowed by the rush to build new systems.

Ramonage et Toit’s move reflects a wider shift in the building trades: contractors expanding into upkeep for energy-producing equipment. The company’s traditional chimney-sweeping and roof-cleaning roots share the same logic as solar maintenance—keeping systems performing over the long haul through routine care.

France’s tax rules have also shifted. Since October 1, 2025, a government order dated September 8, 2025, has set the criteria for a reduced value-added tax (VAT) rate for residential solar equipment with installed capacity up to and including 9 kilowatts-peak. The measure applies to installation, but it signals continued public-policy support for the broader solar sector, including maintenance.

Pourquoi l'entretien solaire devient un enjeu de filière

Rendement en chute silencieuse

La perte de production liée à l'encrassement peut dépasser 20 % par an, sans signal d'alerte visible pour le propriétaire.

Durée de vie préservée

Un entretien régulier prolonge la durée de vie des panneaux à plus de 25 ans et évite des réparations coûteuses.

Artisans locaux en première ligne

Des entreprises comme Ramonage et Toit élargissent leur offre vers la maintenance photovoltaïque, capitalisant sur leur maîtrise du travail en toiture.

TVA réduite depuis octobre 2025

L'arrêté du 8 septembre 2025 encadre les conditions du taux réduit de TVA pour les installations solaires jusqu'à 9 kWc dans les logements.

Marché de la maintenance en expansion

La progression du parc photovoltaïque domestique génère un besoin croissant d'entretien, segment longtemps sous-exploité par la filière.

Ramonage et Toit bets roof know-how matters for solar cleaning

The company is part of a network of local tradespeople turning panel cleaning into a standalone service, with specialized equipment and safety procedures for working at height. That roofing experience is a key differentiator: cleaning panels installed on a pitched roof requires specific skills, not the same approach as washing equipment from the ground.

The approach mirrors what national operators in the sector emphasize—careful selection of technicians, technical know-how, and professional tools to ensure panels are cleaned without scratches or residue. For homeowners in Loire-Atlantique, a local provider also offers faster response times and familiarity with the area—two factors that matter when the job involves getting onto a roof.

With solar installations capable of running for more than 25 years, routine upkeep is no longer a minor consideration. It directly affects the return on investment for equipment whose upfront cost remains significant for households.