SMA SUNNY TRIPOWER X 20-US - Cleaning the Fans

11 Troubleshooting
SMA Solar Technology AG
Operating manual STPxx-US-50-BE-en-11 89
Device required for safe disconnection and short-circuiting of the PV
modules
The insulation resistance can only be measured with a suitable device for safe disconnection
and short-circuiting of the PV modules. If no suitable device is available, the insulation
measurement must not be carried out.
Procedure:
1. Calculate the expected insulation resistance per string.
2. Disconnect the inverter from all voltage sources (see Section9, page67).
3. Install the short circuit device.
4. Connect the measuring device for insulation resistance.
5. Short-circuit the first string.
6. Set the test voltage. The test voltage should be as close as possible to the maximum system
voltage of the PV modules but must not exceed it (see datasheet of the PV modules).
7. Measure the insulation resistance.
8. Eliminate the short circuit.
9. Measure the remaining strings in the same manner.
☑ If the insulation resistance of a string deviates considerably from the theoretically
calculated value, there is a ground fault present in that string.
10. Reconnect to the inverter only those strings from which the ground fault has been eliminated.
11. Reconnect all other strings to the inverter.
12. Recommission the inverter.
13. If the inverter still displays an insulation error, contact the Service. The PV modules might not be
suitable for the inverter in the present quantity.
Also see:
• Calculating the insulation resistance⇒page87
11.4 Cleaning the Fans
If the inverter reduces its power due to overtemperature or even switches off, it is possible that the
fan on the bottom of the inverter is no longer working properly due to contamination. Clean the fan
as described in the following.
1. Disconnect the inverter from all voltage sources (see Section9, page67).