Is solar worth it in Scotland? What latitude and weather really do

What being further north really changes

Latitude changes the shape of the solar year more than its total. The further north you go, the lower the midday sun sits, so winter light is weaker and winter days are shorter. In summer the pattern flips. Days run long, the sky stays light late into the evening, and a Scottish roof gathers light for hours after a roof on the south coast of England has gone dark.

Panels respond to light, not heat. A cool, bright day suits them well, and solar cells lose a little efficiency when they get hot. That is why the strongest month for a Scottish roof tends to be late spring rather than the warmest weeks of summer. For a well-angled Dundee roof, PVGIS puts May first, at 122 kWh for each kW of panels, ahead of July at 116 (PVGIS 5.3).

Cloud matters far more than temperature. Light still gets through thin cloud, so a bright overcast day produces something. Thick, low cloud cuts output hard. Scottish weather changes a great deal over short distances, which is why two places at much the same latitude can give quite different results.

What the Met Office records show

The Met Office publishes long-term averages for its weather stations, covering 1991 to 2020 (Met Office). Five Scottish stations show the spread between east, west and north.

Edinburgh and Aberdeen get almost exactly the same sunshine, about 1,449 and 1,447 hours a year. The Glasgow station at Bishopton logs less, 1,344 hours, with nearly twice Edinburgh's rainfall. Lerwick, in Shetland, has the least sunshine of the five and the most rain days, 204 a year.

Rain does no harm to the panels themselves, and it rinses dirt off the glass. What costs output is the cloud that brings the rain. The wetter west does show up in the modelled yields below, but by much less than the rain gauges might suggest.

What PVGIS gives across Scotland

PVGIS is the European Commission's solar model. It estimates a typical year's output from satellite weather records for 2005-2023 (PVGIS 5.3). This guide ran it for 12 Scottish places, per kW of panels, with standard allowances for system losses. The table groups them by region.

The east coast leads. Dundee comes top at 945 kWh per kW a year, with Perth, Edinburgh and Aberdeen close behind. All four beat central Manchester, where the same model and settings give 888 kWh. Glasgow, at 855, sits about 6% below Edinburgh. The Highlands and Islands come lower again, and Fort William, in the wet west Highlands, is lowest of all at 675.

Even the lowest figure is a working figure. A Fort William roof still makes about 71% of what the same roof would make in Dundee, by our arithmetic. The yield-by-place page breaks every one of these places down by roof direction and pitch.

Long summer days, dark winters

The north changes when the power arrives, not just how much. The table sets a well-angled roof in Dundee beside one in Lerwick, month by month.

In May, Lerwick makes 120 kWh per kW against Dundee's 122, almost level, because Shetland's long days make up for its weaker sun. Kirkwall, in Orkney, goes further and edges past Dundee that month with 125. December is another story: Dundee makes 24 and Lerwick 8, so Dundee produces about 3 times as much.

Over the year, by our arithmetic, 69% of Dundee's output arrives between April and September. In Lerwick it is 78%. The three darkest months, November to January, give Dundee 10% of its year and Lerwick 5%. The further north you live, the more your system is a spring and summer machine.

That matters for anything you plan to run from the panels. Summer surplus is common, and winter shortfall is certain. A battery can move some summer daytime power into the evening, which the battery guide covers, but no home battery carries summer power into December.

When panels suit a household, and when they don't

Location sets the ceiling. Your house and your habits decide how close you get to it. Panels are more likely to suit a home where:

• Someone uses power in daylight. People working from home, retired households, and homes that run washing, dishwasher or an electric car charger during the day use more of their own output directly.
• The roof faces somewhere between east and west through south, with a clear run of slope and few vents, skylights or dormers in the way.
• Little shades the roof. A chimney head, a tall tree or a neighbouring tenement can cast long shadows when the sun is low, which in Scotland is much of the year.
• The roof is sound, or due for repair anyway, so the work can be done once before panels go on.

To put your own roof in proportion, start from your electricity bill, which shows the kWh you use in a year. Ofgem treats 2,500 kWh as typical for a home (Ofgem). Take the Energy Saving Trust benchmark for a home system, 4.5 kWp. On a south-facing pitched roof it would make roughly 3,050 kWh a year in Fort William and 4,200 kWh in Dundee, by our arithmetic from PVGIS. Either way, the panels make more over a year than a typical home uses. The real question is timing: how much of that output lands at a moment when the house can use it.

They are less likely to suit a home with only a north-facing slope, heavy shading, a roof that will need stripping in a few years, or a household that is out all day and uses little power. Flats and tenements raise questions about who owns the roof, which the guide to tenements and flats explains. For a flat with no roof of its own, the plug-in solar guide covers the small balcony units allowed from August 2026.

Planning is rarely the obstacle. Most homes can add roof panels without applying, though listed buildings, World Heritage Sites and some roof slopes in conservation areas are exceptions (permitted development order). Once you know the roof suits, the cost guide sets out what Scottish households paid per kW in the latest official data, and the installer guide explains how to compare quotes.