2 FM80

[vincjwan]

i have to install 12 panels 545 Watts each(isc 14A, Voc 50V)
i have 2 FM80
what do you suggest to configure them ?? and what cables thickness i would use ?
thx

[raysun]

i have to install 12 panels 545 Watts each(isc 14A, Voc 50V)
i have 2 FM80
what do you suggest to configure them ?? and what cables thickness i would use ?
thx

This for a 48V nominal battery?

6 panels per FM80

The individual arrays:
2 panels in series (100Voc)
3 series strings in parallel

Each array needs a combiner box to connect the parallel strings (2 combiner boxes in total, each with at least 3 series connections via fuse or circuit breaker). Each string should be connected to the combiner using 10AWG wire rated for solar panel use. The connection from the combiner output to the FM80 PV input should be via an 80A disconnect (circuit breaker) and 6AWG wire.

Programming the FM80s will depend on the specific battery connected. Has that been identified?

[vincjwan]

yes sure it's clear ... thx

another thing could i install 8 panels (2 in series and 4 in parallel) for the first FM80
and 4 panels(2 in series and 2 in parallel ) for the second FM80 ????
cause i have a problem with the wiring for the second one .

any problem with that ??
thx

[raysun]

8 panels @ 545 Watts = 4360 Watts for the array. It exceeds the FM80's recommended limit of 4000 Watts sufficiently to put the controller at risk of overload, and possibly failure. I'd advise against the 8 panel array.

What sort of wiring issue is there?

[vincjwan]

I have 16 mm2 cables for the first one(Fm80) and 6 mm2 for the second one and it's difficult to change them

[raysun]

I have 16 mm2 cables for the first one(Fm80) and 6 mm2 for the second one and it's difficult to change them

Those are cables feeding the PV input to the FM80s?

Also, what is the brand and model number of the solar panels?

[vincjwan]

Yes from PVs to Controller.
Pvs : philadelphia 545w bifacial

[raysun]

A 6 panel array (2 x 3) would have a maximum power current of just under 40A. 6mm² wire is rated at 47A (free air), 30A in conduit. Since full output current is rare, the 6mm cable might be able to handle the array, but is a bare minimum to be sure. To protect the wiring, use a DC circuit breaker of a size commensurate with the wire's rated capacity.

The 16mm² cable, of course, can handle the 40A current.

Are there two combiner boxes, one for each array, at the location of the arrays? The 6mm² and 16mm² cables are the output from the combiner going to the PV input of the two FM80s?

Keeping the arrays under the 4kW power limit will help assure a long life for the FM80s.

[vincjwan]

Yes it's clear ... Thx a lot
And sure i have 2 combiner boxes for each array at the location of the arrays.
And the 6mm2 and 16mm2 are the Pvs input to the FM80s.
I will put a breaker of 50A at the end of 6 mm2 cable ... Good?

[raysun]

I will put a breaker of 50A at the end of 6 mm2 cable ...

The breaker is there to protect the cable. I'd suggest 40A DC breaker for the 6mm.

[vincjwan]

Ok i'll do it
Thx

[vincjwan]

another question ...
can i use mc4 parallel connectors ? or combiner boxes is better ???
thx

[raysun]

another question ...
can i use mc4 parallel connectors ? or combiner boxes is better ???
thx

Combiner boxes are a safer and more robust option.

MC4 parallel cables are prone to overload at the end of connection chain.

[vincjwan]

ok
thx a lot

[vincjwan]

I already installed the new panels and new FM80 ... Any settings must be done ??

[raysun]

Is this the battery in the system?

[vincjwan]

No ... It's cousin's one ...
Exide Enersol T 2V (450A) 24 batteries 5 years old.
FXR3048E - 2FM80 - Mate3

[raysun]

Do you have the factory charging specifications for the battery?

[vincjwan]

yes , and i don't have problem setting the 2 FM with batteries settings, so the point is that could i make some settings to let the 2 FM to work together in all cases(Absorption and floating) ... or they do that automatically when they are connecting to the same HUB ???

[raysun]

Both FM80 need to be manually programmed with the same charging parameters. Absorb Voltage, Absorb Time, Float Voltage, Re-Bulk Voltage, EQ Voltage, EQ Time, and Auto EQ Interval should be set to equal values on both FM80. End Amps = 0 on both FM80.

Further, the combined maximum charging current output from the two FM80 must be adjusted to match the battery's maximum allowed charging current. The theoretical maximum output of the combined FM80 is 160A. If the battery's maximum charge current specification is, for example, 60A, then the Maximum Current setting on the two controllers must be set such that their values add to no more than 60A. The two Maximum Current values need not be the same, and it may take some experimentation to get optimum settings, dependent on array permance. As a practical measure, the FM80 that draws from array that uses the 16mm² cable to feed current could be set to a higher Maximum Current value than the FM80 drawing current from the array wired with the 6mm² cable.

Finally, in order to work in tandem, both FM80 must be calibrated to the battery voltage.
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