This is the generation of the system divided by the peak rated output of the system. You can use this map to compare the amount you have generated with the amount generated by others.

The size of the system is accounted for, but other factors are not. Generation levels will be affected by the direction in which your panels face, their slope and the amount of sunlight you have enjoyed.

You can read more about how we calculate the generation per kWp of installations in the faq in the online forums.

Measured in kWh/kWp

This is amount of electricity registered at the inverter or generation meter. It shows you how much you have generated, but does not enable you to compare your system with others as it is dependent on the size of your system as well as the direction it faces and the local weather conditions.

Measured in kWh

The efficiency is the amount of electricity produced by your PV installation per unit of energy received. This allows you to make a good comparison with other systems as it takes into account the weather conditions at the site and the direction that your panels face.

The reported values will generally improve in winter as the panels get more efficient with lower temperatures, however this will be countered in some instances by additional shading (as the sun is closer to the horizon) or snow.

You can read more about how the efficiency is calculated in our faq forum.

Measured in %

This is the amount of solar light energy received by the panels during the period specified. It is dependent on the weather conditions at the site, but also on the direction and angle of tilt of the panels.

Panels receive energy direct from the sun, as well as energy which is reflected from the clouds or surfaces. The latter type of energy is referred to as “diffuse”. In the UK panels are usually tilted toward the south to enable them to receive more direct solar energy. Tilting them in this way leads to them receiving less diffuse energy as they “see” less sky, but there is still a net gain, up to a slope of around 35 – 40 degrees.

Measured in kWh/m²

This is the amount of solar energy landing on a square metre of horizontal surface at the locations of installations for the period specified.

Use this map to compare the amount of energy available at sites around the country.

Measured in kWh/m²

This shows you the amount of energy generated for each square metre of panels that you have. Some panels are more efficient than others so will generate more under the same conditions. The values reported here are still subject to environmental conditions at the site and the direction the panels are facing.

Measured in kWh/m²

The performance ratio is the efficiency divided by the peak panel efficiency. This is expressed as a percentage. If the panels are running perfectly and their is no other loss in the system, then this measure should be 100%. In reality it should never go above 100%, apart from in very exceptional conditions, for example if the weather is very cold.

Another reason it should not go above 100% is that system losses occur in other areas of the system, such as the inverter and cabling. These are not accounted for in our analysis.

This feature is new, and while it is a good metric for comparing systems, figures of greater than 100% are often seen. This is likely to be due to local variations in climate, so we are currently carrying out research into this. If you think that your reported levels are not representative of your system, or if you are confused by this metric, please contact us to discuss.

Measured in %