Fixed Tilt vs Tracking Solar 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 single-axis tracker lifts UK annual output by roughly 20 to 35 percent over fixed panels, to around 1050 to 1250 kWh per kWp against 830 to 950 fixed, with dual-axis trackers adding a little more again. The catch is that trackers are ground-mounted structures with motors, bearings and controls, adding roughly 30 to 50 percent to system cost plus ongoing maintenance, which is why they appear on farms and solar parks rather than houses.

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

For domestic and most commercial buyers the maths almost always favours spending the tracker premium on simply installing more fixed panels, which buys more annual energy than the tracking gain delivers, with nothing to service. Tracking earns its keep where land is expensive or constrained relative to the value of energy, in high-latitude summer-heavy generation profiles, and at utility scale where maintenance is professionalised. Trackers also need planning permission as ground structures, wind-rated foundations and clear space; roof-mounted tracking is effectively impractical. If the appeal is more even generation through the day rather than pure volume, an east-west fixed split achieves much of that shape at no extra mechanical cost.

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.