North vs South Facing Solar Panel Energy Output Calculator

How this calculator works

This calculator works in ranges rather than single figures, because real quotes, yields and tariffs genuinely vary that much. It starts from typical UK price, output and savings ranges drawn from published 2026 industry guides and official scheme documentation, then scales them by the quantities you enter and adjusts them for each choice you make below. The result is a low-to-high band that a realistic outcome is likely to fall within, not a promise of the figure you will achieve.

A south-facing array in the UK generates around 830 to 950 kWh per kWp per year, while an identical system facing due north produces roughly 35 to 40 percent less, around 500 to 600 kWh per kWp. On a 4 kWp system that difference is roughly 1200 to 1500 kWh a year, worth to at 2026 electricity prices.

System size

Solar systems are sized in kilowatts peak (kWp), the output of the panels under standard test conditions. A 4 kWp system of around 10 modern panels is the most common choice for a UK three bedroom home, while larger households, or homes with an electric vehicle or heat pump, often go to 6 kWp or more. Bigger systems cost less per kWp because fixed costs such as scaffolding, the inverter and installer overheads are spread across more panels, and the calculator reflects that economy of scale.

Region (solar resource)

The same panels generate more in Cornwall than in Caithness. The industry baseline is around 850 kWh per year for every kWp installed on an unshaded south-facing roof in an average UK location, with southern England running around 5 percent above that and Scotland 10 to 15 percent below. The calculator scales its output and savings figures accordingly.

What else affects the figures

Orientation losses are not linear around the compass: south-east and south-west give up only around 5 percent, and straight east or west around 15 percent, which is why east-west split arrays are common and effective, spreading generation into mornings and evenings when households actually use power. North-facing panels are occasionally justified on shallow-pitched roofs, where the orientation penalty shrinks because the panels lie flatter, or when every other face is full, but on a steep north roof the economics rarely work. Panel pitch, shading and the local solar resource all interact with orientation, so an installer’s MCS generation estimate for each specific roof face is the number to compare before deciding.

Certification, planning and grid connection

If a calculation here prompts a project, the practical next step is an MCS-certified installer’s survey: MCS installers must provide a location-specific generation estimate using the standard industry methodology, which turns the broad ranges on this page into a figure for your actual roof. Most domestic solar work falls under permitted development, with the usual exceptions for listed buildings, flats and conservation areas, and installations must be notified to the district network operator under the G98 or G99 procedures, which a competent installer handles as part of the job.