For each PV module type you have to enter the module data, declared by manufacturer, as shown below.

Pmax

Nominal power of PV module

Umpp

Voltage on maximum power point

Impp

Current on maximum power point

Uoc

Open circuit voltage of module

Isc

Short circuit current of module

NOCT

Nominal working temperature of PV cell

alfa

Temperature coefficient of Isc

beta

Temperature coefficient of Uoc

gamma

Temperature coefficient of Pmax

Rs

Serial resistance of PV module


Not all the module data are always available.

The values for Pmax, Umpp, Impp, Uoc, Isc and NOCT are usually available.

But Temperature coefficients and Serial resistance of PV module are not always available in requested form.


Temperature coefficients

If the data for temperature coefficients are available, they are listed in two forms:

a) Absolute form, shown on example below:

alfa[abs]

Temperature coefficient of Isc

2,84 mA/K

beta[abs]

Temperature coefficient of Uoc

-125,8 mV/K

gamma

Temperature coefficient of Pmax

usually listed in relative form

b) Relative form, shown on example below:

alfa[rel]

Temperature coefficient of Isc

0,034 %/K

beta[rel]

Temperature coefficient of Uoc

-0,34 %/K

gamma[rel]

Temperature coefficient of Pmax

-0,48 %/K


Conversion equations between absolute and relative forms are as follows:

alfa[rel] = alfa[abs] * 100% / Isc

beta[rel] = beta[abs] * 100% / Uoc


MI 3108 and MI 3109 operate with absolute values of alfa and beta and relative value of gamma.


Serial resistance of PV module (Rs)

If the data for Rs is not available, value of 0,4 should be used first.Then perform the measurement with this values, save the results, transfer to PC SW EuroLinkPRO or MESM, open the file, select the measurement and start PVAnalyse tool.
This tool, based on measurement results, calculates the more precise value of Rs. This value should be used then instead the default value of 0,4.