SMP100 Manual

10
Coming back to our example solar panel, the Mitsubishi PV-MLE270HD, the Isc for one panel
is 9.18 amps, and from the charts we can see that there is almost no temperature coefcient.
Assuming 5 panels in series for 1350 watts per string, and 7 strings for a maximum power of
9450 watts, the maximum short circuit current would be 9.18 x 7 or 64.26 amps. Multiplying
this times the safety factor of 1.56 gives a maximum of 100 amps, so likely in this case,
the same wire could be used for the input wiring as the output wiring assuming similar run
lengths.
Circuit Protection
All electrical circuits require protection from over current and short circuits and the SolarMax
is no exception. The SolarMax should be installed with circuit breakers or fused disconnects
on the input and output. The SolarMax has a maximum current limit of 100 amps on the output
and it is designed and listed to run at its maximum rating continuously. A breaker or fuse rated
at 100 amps carrying current at the highest expected ambient temperature should be wired
between SolarMax and the battery bank.
The maximum input current needs to be calculated. The best way is to divide the array power
by the array maximum power voltage. In our example above, we have an array power of 9450
watts and a maximum power voltage of 160 volts giving a maximum input current of 60 amps,
only slightly less than the short circuit current. So the minimum circuit breaker or fuse rating is
60 amps at the highest expected ambient temperature.
If a disconnect is tted on either the input or the output of the SolarMax, it should have a
minimum current rating equal to the maximum input or output current as calculated above.
circuit would require a 160 amp input breaker. Of course the 1.56 multiplier has to be applied
specically to your installation and if your anticipated Isc is lower then the wiring and
disconnects will reect this.
Lightning Protection
Like any other electronic device the SolarMax may be damaged during lightning storms if left
unprotected. We strongly recommend that external lightning protection devices be included as
part of the circuit protection equipment.