Estimates for unshaded panels facing due south. Best tilt uses the Jacobson and Jadhav (2018) latitude fit to NREL PVWatts data; percentages and seasonal angles come from a solar geometry model. For a site-specific check, use the optimise slope option in PVGIS. Roof work and mounting must follow building rules and the installer’s structural checks.
Formula and breakdown
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This solar panel angle calculator gives the best fixed tilt for south-facing panels in UK and Irish cities and European capitals, or at any northern latitude you enter. It also shows the best summer and winter angles, how much a seasonal change really adds, and what share of the best yield your own roof pitch collects.
Quick answer: A solar panel angle calculator finds the tilt that collects the most sunlight over a year. In the UK and Ireland the best fixed tilt for south-facing panels is about 34° to 38°, rising further north; a published analysis gives 34° for London. Anywhere from about 30° to 45° loses under 2%, while flat panels lose about 11%.
What Is a Solar Panel Angle Calculator?
A solar panel angle calculator is a tool that estimates the tilt from horizontal at which a fixed solar panel receives the most energy over a year at a given latitude. The sun sits lower in the sky the further north you are, so panels need to be steeper to face it, but not as steep as the latitude itself because summer sun, high in the sky, delivers most of the year's energy.
The headline figure uses a formula published by Jacobson and Jadhav in 2018 from NREL PVWatts data for the northern hemisphere: best tilt = 1.3793 + L x (1.2011 + L x (-0.014404 + L x 0.000080509)), where L is latitude in degrees. The Stanford paper on world optimal tilt angles also lists values for individual stations, such as 34° for London and 36° for Kilkenny. The percentages and seasonal angles come from a solar geometry model that tracks the sun's position through the year and splits light into direct and diffuse parts.
How Do You Use the Solar Panel Angle Calculator?
- Pick your city from the list, or choose custom latitude and enter your latitude in degrees north with a sky type.
- Enter your roof pitch or planned frame tilt in degrees, where 0 is flat and 90 is vertical.
- Read the best fixed tilt and, where available, the published value for that city.
- Check the summer and winter tilts and the extra yield from adjusting twice a year.
- Compare your tilt with the best, and scan the bars to see how yield changes from flat to vertical.
Which Angle Is Best for Solar Panels in the UK?
For south-facing panels in the UK, the best fixed tilt is about 34° to 38° from horizontal, slightly steeper in Scotland than in southern England. The latitude formula gives 36° for London, 37° for Manchester and 38° for Edinburgh, while the published station values are 34° for London and Hemsby in Norfolk. The difference matters little: the yield curve is very flat near the top, so a typical pitched roof between 30° and 45° collects about 98% to 100% of the best annual total. If your roof does not face south, the solar panel orientation calculator combines direction and tilt.
Is It Worth Changing the Tilt Between Summer and Winter?
Adjusting the tilt twice a year adds only about 3% to annual output in the UK, so it rarely justifies adjustable roof mounts. In London the model's best summer tilt is about 21° and the best winter tilt about 57°, but winter sunshine is weak, so the steep winter angle gains little in absolute terms. Seasonal adjustment makes more sense for ground-mounted or off-grid systems where winter output matters most, such as a cabin that is used in December. For those, compare winter energy with the off grid solar calculator.
How Flat Can Solar Panels Be Before Problems Start?
Keep panels at 15° or more where you can, because the Energy Saving Trust advice on solar panels notes that rain will clean panels tilted at 15° or more in the UK. Flatter panels collect dirt and leaves, and water can sit along the lower frame. On flat roofs, frames usually tilt panels up for this reason. A completely flat panel gives about 89% of the best annual yield in London in this model, so the cleaning effect is often a bigger concern than the angle loss.
How Much Do Vertical Panels Lose?
Vertical, south-facing panels collect about 70% to 75% of the best annual yield in the UK and the Nordic countries, and about 66% in Madrid. They lose most in summer, when the sun is high, and do relatively well in winter. That makes vertical mounting acceptable for balcony railings and facades where nothing else fits; see the balcony solar calculator for that case.
Best Solar Panel Angles for UK and European Cities
Values for unshaded, south-facing panels. Best fixed tilt uses the latitude formula; seasonal angles and the flat and vertical figures come from the geometry model.
| City | Latitude | Best fixed tilt | Summer tilt | Winter tilt | Flat vs best | Vertical vs best |
|---|---|---|---|---|---|---|
| London | 51.5° N | 36° (published 34°) | 21° | 57° | 89% | 71% |
| Manchester | 53.5° N | 37° | 23° | 59° | 88% | 72% |
| Edinburgh | 56.0° N | 38° | 25° | 61° | 88% | 73% |
| Belfast | 54.6° N | 37° | 24° | 60° | 88% | 73% |
| Dublin | 53.4° N | 37° | 23° | 59° | 89% | 72% |
| Paris | 48.9° N | 35° | 21° | 57° | 89% | 70% |
| Berlin | 52.5° N | 36° | 23° | 60° | 87% | 72% |
| Madrid | 40.4° N | 32° | 17° | 55° | 88% | 66% |
| Rome | 41.9° N | 32° (published 30°) | 18° | 55° | 88% | 67% |
| Stockholm | 59.3° N | 39° (published 41°) | 27° | 63° | 87% | 75% |
Published values are the nearest station in Jacobson and Jadhav (2018); Rome uses the Vatican City entry. For a site check with European satellite data, the PVGIS user manual explains its option to optimise the slope for your exact location.
Worked Example: Fiona's Roof in Edinburgh
Fiona in Edinburgh has a south-facing roof pitched at 45° and a flat-roofed extension where she could fit panels on 20° frames. She wants to know which gives more per panel.
- The best fixed tilt for Edinburgh is about 38°.
- Her 45° roof collects about 99% of the best annual yield, a loss of roughly 1%.
- Panels on 20° frames collect about 97.5%, still above the 15° rain-cleaning threshold.
- Flat panels on the extension would drop to about 88% and need more cleaning.
Both options are close, so Fiona's choice comes down to shading, space and cost. She uses the main roof first, and her installer checks that the roof structure can take the load and that any frames on the flat roof are fixed to suit wind exposure.
Frequently Asked Questions
What angle should solar panels be in the UK?
About 34° to 38° from horizontal for south-facing panels, a little steeper in Scotland. Any pitch from about 30° to 45° collects around 98% or more of the best annual yield, so most pitched roofs are already close to ideal.
Is the best solar panel angle equal to my latitude?
No. In the UK the best fixed tilt is roughly 15° to 18° less than the latitude, because most yearly energy arrives in summer when the sun is high. Setting panels at your latitude, around 51° to 56°, would lose a little energy compared with the optimum.
Do flat solar panels work in the UK?
Yes, but a flat panel collects about 11% to 13% less than one at the best tilt and stays dirtier, because rain cleans panels well only at 15° or more. Most flat-roof installations use frames to tilt panels for this reason.
How much does a seasonal tilt adjustment add?
Adjusting twice a year, flatter from April to September and steeper from October to March, adds about 3% to annual output in the UK. It is rarely worth adjustable roof mounts but can help ground-mounted or off-grid systems that need more winter power.
What angle is best for winter solar output?
Steep angles of about 55° to 63° give the most energy from October to March in the UK and northern Europe, because the sun stays low. Vertical panels also perform relatively well in winter and shed snow easily, though they lose a lot in summer.
Does the panel angle matter more than the direction?
Near the optimum, angle matters less than direction. Moving from 35° to 45° costs about 1%, while turning from south to east or west costs around 15% to 20%, according to the Energy Saving Trust. Shading usually matters more than either.
Checked October 2026 by the Solaxyra Editorial Team. Sources: Jacobson and Jadhav (2018), World estimates of PV optimal tilt angles, Energy Saving Trust, PVGIS user manual, Wikipedia: Position of the Sun.