hypothetically...

[plongson]

I have a classic 250 and run 10-235w panels at 180v and 16 amps. Could I double my array (add a second) and still run the same controller and not have to double up and add a second?? Still  at 180v but 32 amp.

[niel]

no you can't double it without getting another controller. as a matter of fact, you are borderline maxed out now because the mppt action will up the current when the voltage is lowered. roughly figuring 180v/48v=3.75. multiplying the 16a delivered by your array by 3.75 puts it at 60a. going by the graph in the manual on page 8 shows that for a 48v battery bank the current out max is about 58a. you may be seeing lower current due to panel inefficiencies, but you are basically maxed out.

[boB]

I have a classic 250 and run 10-235w panels at 180v and 16 amps. Could I double my array (add a second) and still run the same controller and not have to double up and add a second?? Still  at 180v but 32 amp.

You really have to look at the output current when rating these things.  For a 48V battery, you should be good for about 3000 watts or so, so I would say that you can't "double" the array size, but you can go somewhat larger in wattage.  You have 2350 watts of array now and usually won't get that much out of the array (that's just the way this stuff works), so in reality you could ALMOST double that array.

Classic 250 is good for around  55 Amps output and 48V battery.  If your battery is at, say, 52 volts, then the power you would be getting into that battery at 52 volts would be  55A times 52V = 2860 watts....   A bit more power at higher than 52 V battery voltage and a bit lower power at lower than 52 volts battery.

boB


PS...  With Niels answer, which is also correct, you will really need another Classic in order to actually double the array wattage.
It's not always black and white because the nameplate rating of the PV array isn't necessarily what you can actually get out
of it.

[plongson]

So what you guys are saying is I'd then have the "slave/master" configuration noted in the documentation? Does the slave then follow the charge setting from the master or do they have to set the same?

[boB]

So what you guys are saying is I'd then have the "slave/master" configuration noted in the documentation? Does the slave then follow the charge setting from the master or do they have to set the same?

Well, the master/slave following will be coming up pretty soon but until that software update comes, they will work pretty well together just being set up similarly.  As long as the charge controllers are in "BULK", or "MPPT", which means that the battery voltage is below the set point voltage, all will be good.  If the battery voltage is very close or "on the edge" of the set point, and one CC is in MPPT while the other is in Bulk or Float, it is still OK because the batteries are getting charged, which is the most important requirement of the system.

Master/Slaving things will be more desirable of course, especially for wind turbines, but will also keep all Classic charge stages coordinated.

boB

[plongson]

Thanks boB,
So essentially the second controller output is connected to the buss that feeds current to the batteries?