Facing and tilt: how much your solar panels yield in France
A due-south roof is not essential. Here is what each facing and pitch loses, calculated with PVGIS, and why an east or west roof pays back almost as well.
The ideal facing for a solar panel in France is due south, with a tilt close to 35°: that is the reference, at 100%. But the gap with other roofs is smaller than people think. By our calculations with PVGIS, the European Commission’s tool, a 30° roof facing south-east produces 95 % of that reference in Paris, an east-facing roof 81 % and a west-facing roof 79 %. Modules laid flat give 84 %, and a north-facing roof at 30° drops to 56 %. Above all, lost output translates into less lost money than it seems: an east roof produces in the morning, when the house is using power, and self-consumes a larger share of its output. For a 4,500 kWh Paris household with 3 kWp, self-consumption rises from 47 % due south to 55 % due east, and payback only lengthens from 18.0 years to 19.5 years.
How much do you lose with your roof’s facing?
Output vs due south at 35°
81 %
| Loss (or gain) | −19 % |
| For 3 kWp in Paris | 2,776 kWh |
Factors calculated with PVGIS 5.3 for seven reference cities.
Checked by Radif Partners · Editorial policy · Method and sources
The grid of facings and pitches
| Facing (Paris) | 0° | 10° | 20° | 30° | 45° | 60° | 90° |
|---|---|---|---|---|---|---|---|
| South | 84 % | 91 % | 96 % | 99 % | 100 % | 95 % | 71 % |
| South-east | 84 % | 89 % | 93 % | 95 % | 94 % | 89 % | 67 % |
| South-west | 84 % | 88 % | 91 % | 93 % | 92 % | 87 % | 64 % |
| East | 84 % | 83 % | 83 % | 81 % | 77 % | 71 % | 50 % |
| West | 84 % | 83 % | 81 % | 79 % | 74 % | 68 % | 48 % |
| North | 84 % | 75 % | 65 % | 56 % | 43 % | 32 % | 18 % |
Two lessons stand out. Between 20° and 45°, pitch changes a south roof’s output very little: the factor stays above 96 %. Facing matters more, but a south-east or south-west roof loses only a few percent. Gaps widen on steep pitches and towards the north.
North and south do not react the same way
In Marseille, an east-facing roof at 30° produces 77 % of the local reference, against 81 % in Lille. The south therefore penalises off-axis facings slightly more. It still produces far more in absolute terms, as the output by region page shows.
How much of your output will you use yourself?
Self-consumption rate
46 %
| Used on site | 1,620 kWh |
| Exported to the grid | 1,909 kWh |
| Share of the bill covered | 36 % |
| Saving in year 1 | €324 |
Median French output (1,185 kWh/kWp), roof at 30° due south, hour-by-hour calculation.
Why an east roof earns almost as much
Surplus has been paid very little since 5 June 2026: what counts is a kWh produced when the house is using power. A due-south roof concentrates output around midday, when many households are out; an east roof produces early, at breakfast, a west roof until people get home. The self-consumption rate therefore rises as total output falls, and payback barely suffers.
What this calculation does not see
The factors come from PVGIS for seven reference cities and ignore nearby shade: a tree, chimney, dormer or neighbouring building. Shade on part of the modules can cut output more than facing does. Ask the installer for a shading survey, especially if the roof is surrounded.
East-west roofs and flat roofs
A roof with two slopes facing east and west produces less per module than a south slope, but spreads output from morning to evening. In Paris, a module at 30° facing due east gives about 81 % of the reference output. For a household at home in the morning and late afternoon, this spread raises the share used on site, which offsets part of the gap: compare both cases in the calculator. On a flat roof, modules laid flat produce about 84 % of the reference and get dirtier; frames tilted at 10 to 15° improve both, provided the rows are spaced so they do not shade each other in winter.
On a flat roof, fitting also means checking the waterproofing and the load the roof terrace can bear: frames are either ballasted or fixed, and each option has its constraints. Ask the installer which one they propose, with the weight per square metre, before comparing quotes. A ballasted frame avoids drilling the membrane but adds weight; a fixed one is lighter but needs careful sealing at each anchor.