A lot of good replies have come by here but here goes another one...
The GFP cannot be used for dual purpose as a disconnect for battery
or PV input and you are not allowed to un-ground the system by turning
off the DC input or output breaker.
4 AWG should be fine for 80 amps. If you need/want to use smaller wire
than that required for an 80 amp GFP, MidNite makes a 63 amp GFP.
boB
On 4/17/2012 6:42 PM, William Miller wrote:
Friends:
Here is a related problem: If we use an 80 amp GFD (ground fault
detection) breaker, even for a very small array, we have to use 3AWG
CU wire from the battery buss to the breaker and from the breaker to
the FM or MX60. This seems like a big hassle for 5 or 10 amps of
charging. A variety of sizes of GFD breakers would be helpful.
Here is a bigger problem: GFD breakers don't really work. All they
do is turn off the charge function in hopes that someone will find the
problem. In the meantime, the negative-to-ground bond is removed and
module mounting framework could be energized. PV GFD breakers are
completely different from standard AC GFDI (ground fault detection and
interruption) receptacles and circuit breakers. The AC versions
interrupt power upstream, the PV versions interrupt power /downstream/
from the fault.
See:
http://millersolar.com/MillerSolar/case_studies/ground_fauilt/_ground_fault.html
for some musings on the subject.
As they say on TV: "There had to be a better way!"
William Miller
At 05:54 PM 4/17/2012, Kent Osterberg wrote:
Nathan,
I don't think anyone makes a 100-amp PV GFP. The panel mount breaker
model that's being used for the PV GFP doesn't include a 100-amp
breaker.
The Classic has a built-in GFP so you shouldn't need an external GFP
for it. You will need to add a GFP for the FM60 - a single 80-amp GFP
would work.
You can use the dual 80-amp GFP and shut down both PV arrays at the
same time if the GFP is wired to disconnect the PV array from the
charge controller input. That's where Outback's instructions used to
show the GFP, and it is a better place for it than on the charge
controller output anyway. Midnite's instructions show the GFP on the
charge controller input, but their 80-amp GFP is a single.
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com <http://www.bluemountainsolar.com>
On 4/17/2012 11:08 AM, Nathan Stumpff wrote:
Wrenches,
In a job coming up I have a customer with an existing FM60
controller, 520 watt (!!) array. We are doing a ton of work,
including adding a 4 kW solar array with Classic 150 charge
controller. I am trying to figure out how to handle the GFP.
For the Classic, I need a 90 or 100 A output breaker minimum. 80 A
is not an option. The OutBack dual GFP is 80 A, and so it not an option.
Is there a 100 A GFP breaker assembly I have just never seen? Is
there a way to use the Classic's GFP to run an external relay via
AUX (to trip the FM60 output breaker at the same time)? Any ideas?
Thanks,
-Nathan
Nathan J. Stumpff - Arctic Sun, LLC
NABCEP Ceritified PV Installer #091209-175
nat...@arcticsun-llc.com <mailto:nat...@arcticsun-llc.com>
Office: 907/457-1297
_________
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
<http://millersolar.com/>License No. C-10-773985
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