Solar panels in Pays de la Loire
The calculator opens on Nantes. Sunshine rises the nearer you get to the ocean and the south: from the Mayenne to the Vendée coast, the figures.
Pays de la Loire produces a median of 1,202 kWh per kWp a year, slightly above the national median of 1,185, by our calculation on the European Commission’s PVGIS data. The region splits clearly in two. In the south-west, Vendée leads with 1,277 kWh, and a dozen communes on its coast exceed 1,330 kWh, more than Bordeaux (1,283). In the north-east, Mayenne comes last at 1,158, level with the Paris basin. Nantes produces 1,226 kWh per kWp, Saint-Nazaire 1,276, Le Mans only 1,159. For a household using 4,500 kWh a year with 3 kWp, payback is 17.8 years in Nantes and 17.9 years in Le Mans. On the coast, higher output only brings a gain if the house uses power during the day: surplus is bought at just 1.1 c€/kWh.
Pays for itself in · 3 kWp in Nantes
17.8 years
Net result over 20 years: +€771
| Output per year | 3,657 kWh |
| Used on site (44 %) | 1,615 kWh |
| Bill saving, year 1 | €323 |
| Surplus sold (2,043 kWh) | €22 |
| Standing-charge surcharge (export) | −€12 |
| Gain in year 1 | €334 |
| Share of your bill covered | 36 % |
| Price used (estimate) | €6,000 |
| Best-value size (estimated prices) | 2 kWc |
Month-by-month output in Nantes (3 kWp)
December: 134 kWh; July: 425 kWh. PVGIS average 2005-2023.
Checked by Radif Partners · Editorial policy · Method and sources
The five départements
| Département | Median kWh/kWp | Communes: from… to… | 3 kWp pays back in |
|---|---|---|---|
| Vendée (85) | 1,277 | 1,232 – 1,344 | 16.7 years |
| Loire-Atlantique (44) | 1,228 | 1,194 – 1,304 | 17.7 years |
| Maine-et-Loire (49) | 1,214 | 1,191 – 1,244 | 17.6 years |
| Sarthe (72) | 1,171 | 1,121 – 1,202 | 17.9 years |
| Mayenne (53) | 1,158 | 1,111 – 1,207 | 17.9 years |
Output ranges from 1,111 kWh per kWp, in the north of the Mayenne, to 1,344 on the Vendée coast, around Brem-sur-Mer and Les Sables-d’Olonne. Loire-Atlantique follows the same pattern: communes on the Côte de Jade, near Pornic, produce clearly more than those in the north of the département.
Vendée: one of the shortest paybacks in the west
At the Vendée median, 3 kWp for a 4,500 kWh household pays back in 16.7 years, against 17.9 years in the Mayenne. For an 8,000 kWh household in Nantes, the best 20-year size is 3.5 kWp; in Le Mans, 3 kWp. The mini-calculator below opens on the Vendée.
How many years until your panels pay for themselves?
Pays for itself in
16.7 years
| Output per year | 3,808 kWh |
| Gain in year 1 | €356 |
| Installed price (estimate) | €6,000 |
| Net over 20 years | +€1,220 |
Département median, roof at 30° due south, surplus sold at 1.1 c€/kWh.
Go bigger or store?
A household that uses a lot during the day can aim for 6 kWp. A battery shifts surplus to the evening, but its price has to be weighed against the low buy-back rate it avoids: the calculator runs the numbers with and without.