The Scottish Solar Index

First edition: coming 2027

Quick answer

The Scottish Solar Index will publish real generation figures from monitored solar systems on Scottish roofs, grouped by region, roof orientation and system size. The first edition is planned for 2027. Until then, MCS MIS 3002 gives typical central Scotland yields of around 700 to 810 kWh per kWp each year.

Last updated: 17 October 2026

Aerial view of houses with rooftop solar panels

What solar actually produces in Scotland — by region, orientation and system size — from monitored systems, with the sample size, method and limitations stated openly.

Why this matters

Every competitor in Scotland sells opinions about solar yield. Nobody publishes measurements. The Scottish Solar Index will be the first dataset of real generation figures from real Scottish roofs, collected through our Solar Care Club monitoring programme.

What it will include

—Annual kWh/kWp by Scottish region (Central Belt, Highlands, Islands, North-East, Borders)
—Yield by roof orientation and pitch angle
—Seasonal generation patterns for Scottish latitude and weather
—Sample size (n) for every figure, always stated
—Method, limitations and confidence intervals

When

The first edition will publish when our monitored sample is large enough to be meaningful. We will not publish a figure the sample does not support. An honest empty index dated today is worth more than a fabricated full one.

Contribute your data

If you have a monitored solar system in Scotland and would like to contribute your generation data to the index, get in touch. Every contribution makes the dataset stronger.

Contribute your generation data

The Scottish Solar Index is a project of Scottish Energy Efficiency. Current status: data collection. First publication target: 2027.

Why inverter age matters in Scotland

Many Scottish solar systems were installed between 2010 and 2015, when the Feed-in Tariff made panels popular on homes from Dumfries to Inverness. Inverters are normally the first part of a solar system to need replacing, so many of those original units are now reaching the end of their working life.

Scotland’s climate plays a part. Long, damp winters and cold lofts and garages expose inverters to condensation. Coastal homes also face salt in the air. Inverters fitted in a cool, dry and ventilated spot tend to last longer, which is why we look at the location as well as the unit when we survey a system.

Typical Scottish systems

Most domestic systems from that period are around 3 to 4 kWp and use a single string inverter. Typical Scottish yields are around 700 to 810 kWh per kWp each year, according to the MCS standard. If yours is a similar system, an inverter that has dropped offline costs you generation every sunny day. A quick check of your monitoring or generation meter will show whether it is still working.