Solar Output Calculator

Your 4kW system will generate 3,200-3,800 kWh annually in Scotland, with exact output depending on location and roof conditions. East coast locations achieve 3,600-3,800 kWh, while west coast sees 3,200-3,600 kWh. This equals 85-90% of what the same system produces in southern England.

kW (kilowatts) measures your system's rated power capacity—how much it can produce at peak conditions. kWh (kilowatt-hours) measures actual energy generated over time. Your 4kW system produces around 3,600 kWh annually in Scotland, meaning it runs at effective capacity for approximately 900 hours per year at peak conditions.

Scotland receives 85-90% of southern England's solar irradiance due to higher latitude and cloudier weather. However, cooler Scottish temperatures actually improve panel efficiency by 5-10%, partially offsetting this difference. Your panels work more efficiently in Scotland's cooler climate compared to hot summer days in the south.

Your south-facing roof achieves 100% optimal output. Southeast or southwest roofs still reach 95% performance—barely noticeable difference. East or west-facing roofs deliver 85% of optimal, which remains viable. North-facing roofs produce only 55% and aren't typically worth installing solar panels in Scotland.

Shading dramatically reduces output. Light shading (nearby trees, occasional shadows) cuts output by 10%. Moderate shading (partial tree cover, nearby buildings) reduces output 25%. Heavy shading (significant tree cover, tall buildings) cuts output by 50%. Even small shadows can impact entire panel strings, making shade assessment critical.

Solar calculators using industry-standard yield factors typically estimate within 10-15% of actual output. They provide good ballpark figures for planning but can't account for micro-climate factors, future tree growth, or building construction. For precise estimates, you need a professional site survey of your roof.