Ten years ago, “north-facing” ended the conversation. Panels were expensive, batteries were rare, and every kWh had to be generated at the perfect angle to justify itself. The economics have moved on; the received wisdom hasn’t. Here’s the honest picture.
What north actually costs you
In the UK, a north-facing roof typically generates 55 to 70% of what the same array would produce facing south. The exact figure depends heavily on pitch: a shallow north roof (say 20 degrees) loses far less than a steep one, because a shallow panel still sees most of the sky. In high summer, when the sun rises in the north east and sets in the north west, a north array’s mornings and evenings are surprisingly productive.
Our calculator applies a factor of 0.6 to north-facing roofs, deliberately at the cautious end. We would rather under-promise on your proposal than flatter it.
Why the maths changed
- Panels got cheap; efficiency got high. The cost per installed kWp has fallen dramatically while premium panels crossed 23% efficiency. Panels are far cheaper and more efficient than in the early 2010s, so a roof that didn’t pay its way then often can now.
- Batteries decouple generation from use. With a battery, more of what your panels make can replace electricity you’d otherwise buy at full price, allowing for a small loss in charging and discharging. A north roof’s lower yield still displaces 28p electricity.
- Smart tariffs carry the winter. The battery earns year-round on cheap-rate charging regardless of what the roof is doing, so the system’s payback no longer rests on generation alone.
- 0% VAT applies either way, until 31 March 2027. The tax break doesn’t check your compass.
When north genuinely works
The strongest north-facing cases share a few traits: a shallow pitch, no significant shading, decent daytime consumption to soak up generation, and a battery in the design. Households with an east or west roof section available often split the array, taking morning and evening sun on the flanks with the north section topping up the middle of the day.
When we’ll tell you no
A steep north pitch overshadowed by trees or neighbouring buildings can genuinely fail to justify the scaffolding. If the modelled payback stretches beyond the equipment warranties, we’ll show you the numbers and suggest alternatives: sometimes that’s a battery-only system on a smart tariff, which needs no roof at all and can still cut your bills, depending on how and when your home uses electricity.
Every Powergy proposal models your actual roof from satellite imagery, pitch and orientation included. If your compass points the wrong way, ask us anyway; the answer is more interesting than it used to be.
This guide is general information, not advice for your specific property. Every Powergy proposal is modelled on your actual roof, usage and tariff.