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Irradiation Anomaly

The first months of a PV system’s electrical output can provide an impression of its capacity, if you know how to interpret these values. Yet, wrong conclusions can be easily drawn. During a given month, the amount of global horizontal irradiation can fluctuate up to 30% above or below the long-term climatic average for the same month. This deviation is called anomaly.

KiloWattsol offers a documentation of the horizontal irradiation anomaly for the last three months in the form of maps. The issues for one month will be elaborated and released during the first days of the following month.

A negative anomaly means that the horizontal irradiation was below the long-term average. Conversely, a positive anomaly describes an above-average irradiation.

The information presented should be considered only as an order of magnitude, since significant local variations can occur. In case of questions regarding the methodology applied by kiloWattsol during the elaboration of these maps, please do not hesitate to contact us.

An anomaly of the monthly global horizontal irradiation can sometimes trigger an even stronger anomaly of the production, primarily due to the module’s tilt. This is illustrated by the following example for horizontal irradiation and electrical output for a ground mounted PV plant in Munich region for 2011 and 2012.

This chart documents the amplification of the production anomaly in respect to the horizontal irradiation anomaly. For example, the production in November 2011 exceeds the monthly average by 32%, although the horizontal irradiation was only 17% above average.

If you need an in-depth analysis of a project, kiloWattsol can provide you specific and detailed studies (refined climate analyses, capacity audits of operating plants, performance studies...) Contact us.


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