Peak Sun Hours by Location: UK, Europe & Beyond
Peak sun hours (PSH) are the single most important number for sizing your campervan solar system. One hour of peak sun delivers 1,000 watts per square metre — equivalent to full, direct midday sunshine. Knowing your location's PSH tells you exactly how much energy your panels will produce.
This guide is part of our campervan solar setup guide. For the full sizing methodology, see how many solar panels do I need.
Use real PSH data in your calculation
Our free calculator uses location-specific peak sun hours data to accurately size your solar system. Enter your typical usage and get precise recommendations.
What Are Peak Sun Hours?
Peak sun hours are not the same as daylight hours. A peak sun hour is a unit of measurement: one hour of sunlight at an intensity of 1,000 W/m² (full noon sun).
On a typical UK summer day, you might have 16 hours of daylight but only 4–5 peak sun hours. The morning and evening sun is much weaker than midday sun, so those hours contribute less energy.
Example: A day with 6 hours of 500 W/m² irradiance plus 2 hours of 1,000 W/m² is equivalent to 5 peak sun hours (6 x 0.5 + 2 x 1.0 = 5).
This is why PSH is so useful — multiply your panel wattage by PSH to get daily energy output (before efficiency losses).
UK Peak Sun Hours by Region
Annual Average PSH
| Region | City | Annual Avg PSH | Best Month | Worst Month |
|---|---|---|---|---|
| South Coast | Brighton | 3.3 | Jul (5.3) | Dec (0.7) |
| South West | Plymouth | 3.2 | Jul (5.1) | Dec (0.7) |
| London & SE | London | 3.0 | Jul (5.0) | Dec (0.7) |
| East Anglia | Norwich | 3.1 | Jun (5.0) | Dec (0.6) |
| Midlands | Birmingham | 2.7 | Jul (4.7) | Dec (0.6) |
| Wales | Cardiff | 2.8 | Jul (4.5) | Dec (0.6) |
| North England | Manchester | 2.5 | Jun (4.3) | Dec (0.5) |
| North East | Newcastle | 2.5 | Jun (4.4) | Dec (0.5) |
| Lake District | Kendal | 2.4 | Jun (4.2) | Dec (0.5) |
| Central Scotland | Edinburgh | 2.4 | Jun (4.2) | Dec (0.4) |
| Highlands | Inverness | 2.2 | Jun (4.0) | Dec (0.3) |
| Northern Isles | Shetland | 1.9 | Jun (3.5) | Dec (0.2) |
Monthly Breakdown: Southern England
| Month | PSH | Notes |
|---|---|---|
| January | 0.9 | Very limited solar production |
| February | 1.4 | Slowly improving |
| March | 2.3 | Spring equinox — useful solar starts |
| April | 3.5 | Good solar month |
| May | 4.2 | Near peak |
| June | 4.8 | Peak month (longest days) |
| July | 5.2 | Peak output (clearer skies) |
| August | 4.6 | Still excellent |
| September | 3.3 | Autumn decline starts |
| October | 2.0 | Noticeable drop |
| November | 1.1 | Limited production |
| December | 0.7 | Lowest output month |
Monthly Breakdown: Scotland
| Month | PSH | Notes |
|---|---|---|
| January | 0.5 | Very low — DC-DC charging essential |
| February | 1.0 | Slight improvement |
| March | 1.8 | Spring improvement |
| April | 3.0 | Good solar returns |
| May | 3.8 | Strong production |
| June | 4.2 | Peak (long days compensate for latitude) |
| July | 3.8 | Good but cloudier |
| August | 3.4 | Decent output |
| September | 2.5 | Autumn decline |
| October | 1.4 | Dropping quickly |
| November | 0.7 | Very limited |
| December | 0.4 | Near zero useful output |
European Peak Sun Hours
For van lifers who travel in Europe, the difference in solar resource is dramatic. Heading south in winter can multiply your solar output by five or more.
Western Europe
| Location | Country | Annual Avg PSH | Summer PSH | Winter PSH |
|---|---|---|---|---|
| Amsterdam | Netherlands | 2.8 | 4.8 | 0.7 |
| Paris | France | 3.2 | 5.2 | 0.9 |
| Bordeaux | France | 3.6 | 5.6 | 1.3 |
| Barcelona | Spain | 4.6 | 6.8 | 2.5 |
| Madrid | Spain | 4.9 | 7.2 | 2.7 |
| Lisbon | Portugal | 4.8 | 7.0 | 2.8 |
| Algarve | Portugal | 5.2 | 7.5 | 3.2 |
Mediterranean
| Location | Country | Annual Avg PSH | Summer PSH | Winter PSH |
|---|---|---|---|---|
| Marseille | France | 4.5 | 6.8 | 2.3 |
| Rome | Italy | 4.3 | 6.5 | 2.2 |
| Sardinia | Italy | 4.7 | 7.0 | 2.6 |
| Athens | Greece | 4.8 | 7.2 | 2.5 |
| Crete | Greece | 4.9 | 7.5 | 3.0 |
| Dubrovnik | Croatia | 4.4 | 6.8 | 2.2 |
| Málaga | Spain | 5.1 | 7.3 | 3.4 |
Scandinavia
| Location | Country | Annual Avg PSH | Summer PSH | Winter PSH |
|---|---|---|---|---|
| Copenhagen | Denmark | 2.6 | 5.0 | 0.4 |
| Stockholm | Sweden | 2.5 | 5.2 | 0.3 |
| Bergen | Norway | 2.0 | 4.0 | 0.2 |
| Tromsø | Norway | 1.5 | 4.5 | 0.0 |
The further south you go in winter, the better
Moving from the UK to the Algarve in winter increases your PSH from 0.7 to 3.2 — nearly five times more solar energy per day. This is the single most effective way to boost winter solar production.
How to Use PSH in Your Solar Calculation
The formula is:
Daily energy needed (Wh) / PSH / System efficiency (0.73) = Solar watts required
Example 1: UK Year-Round Use
You need 800 Wh/day and want reliable power from March to October in southern England.
Average PSH for March–October: 3.3 800 Wh / 3.3 / 0.73 = 332W — round up to 400W
Example 2: Summer Travel in Europe
You need 1,000 Wh/day and plan to travel in France and Spain from May to September.
Average PSH for southern France in summer: 5.5 1,000 Wh / 5.5 / 0.73 = 249W — round up to 300W
Example 3: UK Winter Use
You need 600 Wh/day through a UK winter.
PSH in December, southern England: 0.7 600 Wh / 0.7 / 0.73 = 1,174W — impractical from solar alone
This example shows why solar alone cannot meet winter needs in the UK. You need supplementary charging. For winter-specific advice, see how much solar do I need in winter.
Factors That Affect Local PSH
Cloud Cover
The UK's high cloud cover is the primary reason our PSH values are lower than latitude alone would suggest. The west coast (Wales, Lake District, west Scotland) is cloudier than the east coast (Norfolk, east Scotland), which is why Norwich often outperforms Manchester despite being at a similar latitude.
Altitude
Higher altitude locations receive slightly more solar irradiance due to less atmosphere to pass through. Mountain passes and highland camping spots can have marginally better solar than valleys.
Coastal vs Inland
Coastal areas sometimes benefit from clearer skies (especially on the south and east coasts of England), but sea fog and haar (coastal fog in Scotland and northeast England) can reduce morning output.
Urban vs Rural
Tall buildings in cities create shading that reduces effective PSH for a parked campervan. Rural and open locations generally provide better solar access.
PSH Data Sources
The data in this guide comes from the European Commission's PVGIS tool (Photovoltaic Geographical Information System), which provides accurate solar irradiance data based on satellite measurements over 10+ years.
For your specific location, you can check:
- PVGIS: re.jrc.ec.europa.eu — the most accurate free tool
- SolarGIS: solargis.com — detailed commercial data
- Met Office: uk historical sunshine data
Choosing the Right PSH for Your Calculation
The PSH you use in your sizing calculation depends on your travel patterns:
- UK only, April–September: Use 3.5–4.0 PSH
- UK only, year-round: Use 2.5–3.0 PSH (accept winter shortfall)
- UK + European travel, summer: Use 4.5–5.5 PSH
- Southern Europe winter: Use 2.5–3.5 PSH
- Design for worst case: Use your location's lowest practical month
Most campervan builders design for an average of 3.0 PSH if staying in the UK, which gives good performance from March through October with DC-DC supplementation in winter.
For a detailed comparison of common solar setups using these PSH values, see 200W vs 400W vs 600W solar.
Frequently Asked Questions
Are peak sun hours the same everywhere in the UK?
No. Southern England receives about 50% more solar energy than the Scottish Highlands on an annual basis. The difference is even more pronounced in winter — the south coast gets roughly double the winter PSH of central Scotland.
Do peak sun hours account for cloud cover?
Yes. PSH values in this guide are real-world averages that include the effect of typical cloud cover. They are not theoretical clear-sky values.
How accurate is the PSH data for a specific parking spot?
PSH data represents the average for a general area. Your specific spot may be shaded by trees, buildings, or hills. The data also averages over multiple years, so any given day can be much better or worse than the average.
Should I size my solar for winter or summer PSH?
For most UK campervans, size for spring/autumn PSH (2.5–3.5). This gives excellent summer output, reasonable spring/autumn performance, and accepts that winter will require supplementary charging. Sizing for winter PSH would require an impractically large array.
Do peak sun hours change with panel tilt?
Yes. The PSH values in this guide assume panels tilted at or near the optimal angle. Flat-mounted panels on a van roof typically receive 10–15% less than the tabulated PSH. In winter, the difference is larger because the sun is lower.
Calculate your solar needs with real PSH data
Our free calculator uses location-specific peak sun hours to size your solar array, battery bank, and charge controller accurately.
Summary
Peak sun hours are the foundation of accurate solar system sizing. The UK averages 2.5–3.3 PSH annually depending on region, with a dramatic seasonal variation from 0.4–0.9 in December to 4.2–5.3 in July. European travel, especially heading south in winter, can dramatically improve your solar resource. Use the tables in this guide alongside our free calculator to size your system correctly for your travel patterns.