6. TESTING, DEBUGGING AND TROUBLESHOOTING
7. MAINTENANCE
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Subject to technical modifications without notice. 2016 © ET Solar Group
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Subject to technical modifications without notice. 2016 © ET Solar Group
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5.4 Electrical ratings of the concerned modules
Troubleshooting for low voltage
For best performance, ensure that positive and negative DC wires run closely together
to avoid loops.
Blocking diode can be used in PV system to prevent reverse current from the battery if
there is no photovoltaic current in the module. If charge controllers are not used, then
it is recommended to use blocking diodes. For more details on charge controllers,
please consult with professionals.
In cases where two or more modules are connected serially in a system, if part of the
modules are occluded and the other part are exposed to the sun, the high reverse
current will flow partially or completely through the module, causing the modules to
overheat and even damaging the modules. Bypass diode used in modules can
protect modules from such impact of excessive reverse current..The bypass diodes
have been integrated in the junction box.
Operators should protect themselves from electrical shock during debugging or
maintenance of solar systems.
There are two causes of low open circuit voltage, environmental change or circuit
fault. The drop of irradiance or increase of environmental temperature reduces the
open circuit voltage, which is normal. The troubleshooting here refers to the low
voltage caused by circuit faults, which is usually due to incorrect connection of
terminals or damage of bypass diodes.
First, check all wiring connections, and ensure they are well-connected into the PV
system. Then check the modules one by one as below:
Measure the open circuit voltage of a module.
Cover the module completely with opaque material.
Disconnect the module from the system.
Remove the opaque material from the module, and measure its open circuit voltage.
If the measured voltage is one third or two thirds of the rated value, it indicates that
bypass diodes don’t work well, and should be replaced.
WARNING!
Electrical shock hazard!
Do not touch bare conductors or other potentially energized parts.
Please refer to ET module datasheets. Datasheets can be downloaded from website:
www.etsolar.com
Use digital multimeter to check the total open circuit voltage of the serially
connected modules. The results should be equal to the sum of the open circuit
voltage of individual modules, which can be found from the label on the modules. If
the total open circuit voltage is much lower than expected, please follow the
following procedure in this instruction.
Test procedure for modules serial connected before connect them to the PV system.
ET Solar recommends the following maintenance items to ensure optimal performance
of the module:
Clean the glass surface of the module as necessary. It is recommended to clean the
glass surface with pressured running water compliance with local drinking standards,
e.g. low mineral content, near neutral PH value. The maximum water pressure
recommended is 1 MPa and the water jet is at least 50cm away from the glass
surface. Do not use dishwasher detergent. Do not have water staying on the glass
surfaces of PV modules for a long time.
If a module power decreases abnormally, and its glass surface is found covered by
dust, please contact your module installer, retailer or ET solar immediately for technical
support.
Do not attempt to clean a module if the front glass is broken or the backsheet is
perforated.
