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Pac Correction Factor
6 Pac Correction Factor
At photovoltaic plants, several measuring points and power generators (inverters) are combined with one
another. The Solar-Log™ evaluates this data and partially looks for any correlations.
Since some of the components are not calibrated, deviations in the values measured can easily arise.
For example, if the total amount of energy produced based on what the inverters display is compared with
the values from calibrated power meters, deviations of up to 8% can arise.
In practice, meters and inverters both can display too much or too little kWh.
To correct these inaccuracies in the medium term, the Solar-Log™ firmware uses a PAC correction factor.
The PAC correction factor is located in the
Configuration | Devices | Configuration
menu.
6.7.1 Calculating the PAC correction factor
All of the yield data is saved internally without the correction factor. The correction factor is only applied
to the data output. The factor can therefore be adjusted at any time.
The formula for calculating the correction factor is as follows:
(Yield power meter / yield inverter) * 1000
If the inverter does not have a display, it is advisable to use the values which are recorded by the Solar-
Log™ from a period over a week.
That is why it is recommended to leave the default PAC correction factor at 1000 initially.
The correction factor can be adjusted yearly after receiving the statement from the utility company.
Example calculation:
Inverter 1
Inverter 2
Calibrated power meter
Total energy
Total energy
Total energy
259.12 kWh
305.22 kWh
550.55 kWh
Total = 564.34 kWh
Deviation= 13.79 kWh
By comparing the values, you see that the inverters are more likely to display too much output.
