Studer Innotec SA
next3
Technical user manual V1.3 © Studer-Innotec SA 45
reduce the cable losses in the system even if a 2.5mm
2
cross section would have been enough. In
any case follow local regulation for cable sizing regarding the short-circuit current (Isc) of the PV
generator and length of cables.
If you wish to install two PV strings in parallel for one MPPT, this can be assembled as well out of the
Next3, for example in the junction box on the roof. This can minimize the number of cables used.
The parallel strings can be connected together before the next3 solar entry as long as the maximal
short-circuit current (Isc) of 22Adc is not reached.
5.4.5
Protection devices
Wiring protection devices (fuses, circuit breakers) connecting the PV generator to the next3
must be installed in accordance with local standards and regulations in force. Special rules
are existing for fire hazard and access to switching devices by firemen.
The internal PV switch of the NX3 disconnects all poles between the PV generator and the
charge regulator.
PV modules are often exposed to stormy weather. It is highly recommended to install lightning
protection. This is mandatory in some countries. Please see local standards and regulations in
force.
5.5 LIGHTNING PROTECTION
According to the installation site, it is highly recommended to develop a protection strategy
for your installation. The strategies depend on various factors specific to each site; we
recommend therefore a professional approach to this issue.
The next3 has internal protections against lightning by means of surge protection devices.
These devices have an energy dissipation capacity limited to 3,5kA (8x20 µs) which
guarantees a certain protection level but are not a total protection against lightning.
Furthermore, these protections are for single use. Therefore, in the event of a lightning strike
where these surge protections are hit, you’ll have to send the unit for repair. They cannot be
replaced nor repaired on site.
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