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P50 -P90 probabilities


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I am a new user of PVsyst software. I would like to know how one can find the P90 value for a particular P50 simulation result in PVsyst 5.68. Is this provision available in this version of PVsyst? Does PVsyst help documentation describe how to manually calculate the same?

Thanks and regards,


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  • 10 months later...

Hi Andre,

We are Owner's Engineers to a client setting up a 20MW solar PV power plant in India.

We have always considered the default PVsyst energy report as equivalent to P-50 estimation. We have now been asked to furnish evidence in support. Is there any available literature or description in PVsyst which says the default energy simulation is P-50 value?


Vivek Jayakumar

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To be able to interpret the simulation output as P50 value, one has to use an average over many years as meteorological input, not the data of a specific year.

The PVsyst default is to use Meteonorm data, which is indeed an average over many years.

If you use a different meteorological source, make sure it represent the average climate of the geographical location, like for example data sets with a Typical Meteorological Year (TMY).

NB: PVsyst also allows to use a shift for taking the climate change into account. We observe - at least in Europe - a significant increase of the annual irradiation (of the order of 5%) with respect to the end of the last century.

See What is the reliability and unceretainties of meteo data ? in our FAQ

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