SMA SUNNY WEBBOX - Manual (Page 55)

SMA Solar Technology AG 8 Plant Properties
User Manual SPortal-WB-CLCON-BA-en-25 55
8.3.4 Changing the Performance Ratio
The performance ratio is a location-independent measure of the quality of a PV plant, and is therefore
often called the quality factor. The performance ratio (PR) is given in percent and describes the
relationship between the actual and target yields of the plant. It thus shows the proportion of the
energy that is actually available for feed-in to the grid after deduction of energy loss (e.g. due to
thermal losses and conduction losses ) and of the requisite operating current.
The closer the PR value determined for a plant is to 100%, the more efficiently the respective plant is
operating. In reality, a value of 100% cannot be achieved, as unavoidable losses always arise during
operation of the plant (e.g. thermal losses due to the warming of the PV modules). However,
high-performance plants can reach a performance ratio of up to 80%.
The parameters for the performance ratio are configured automatically when one of the following
devices is added to your Sunny Portal plant.
• Sunny SensorBox
• Cluster Controller with connected irradiation sensor
Manual adjustment of the irradiation and temperature sensor
In the following cases, you will need to adjust the parameters of the irradiation and/or temperature
sensor manually.
• If there are several Sunny SensorBox devices in the plant
• If there is a Sunny SensorBox and a Cluster Controller with connected irradiation sensor in the
plant
• If the list of parameters has been changed
• If you have replaced a Sunny SensorBox or a Cluster Controller
The reason for this is that the standard page "Performance ratio" in the "Visualization" menu is not
updated automatically.
1. Select "Configuration > Plant Properties".
2. Select the "Parameters" tab.
3. Select [Edit].
4. In the "Irradiation sensor" field, select the sensor based on the serial number of the
Cluster Controller / Sunny SensorBox.
Cluster Controller temperature sensors
If a module temperature sensor is connected to the Cluster Controller, the module
temperature sensor readings are taken into account in the calculation of the performance
ratio. This renders the value of the performance ratio more exact. However, a satisfactory
PR calculation is also possible without a temperature sensor.