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Greenbyte Documentation

Common Solar Concepts

Irradiance Cut-in

Irradiance data is often unreliable because of cheap sensors, night-time moonlight, and so on. It is not uncommon to get spurious irradiance values around 0. Therefore, it is advised to set a threshold to use in the calculations, irradiance cut-in, disregarding all irradiance values below it.

If nothing else is said, it is availability mode and Cut-inIA is used.

Common_Solar_Concepts_-_Irradiance_Cut-in.png

Where:

I

is the irradiance for each time step

Cut-inIP

is the Performance Irradiance Cut-In (W/m2) (Device metadata 16)

Cut-inIA

is the Availability Irradiance Cut-In (W/m2) (Device metadata 15)

Degradation Factor

(Photo-voltaic) solar panels degrade in performance over time. It can be approximated by a yearly degradation factor. The following formula is used in Potential power calculations to calculate the effective degradation factor for a given timestamp, given the commissioning date and yearly degradation factor.

Note

The degradation factor is multiplied by the Potential power value of each timestamp, to obtain the degraded value for that timestamp.

Common_Solar_Concepts_-_Degradation_Factor.png

Where:

DY

is the metadata value (yearly) Degradation Factor set per site

tM(t,u)

gives the absolute difference, in months, between the two timestamps t and u

t0

is the metadata value Commissioning Date set per inverter