Allan, No, not suggesting to get rid of E-panels or wiring centers.
They aren't optimum though,
electrically speaking. My suggestion was more of a technical one
intended to illustrate a
way of wiring to reduce stress on (most) MPPT charge controllers. I
should not have said
it was a a good practice "these days"... That was kind of dumb for me
to say.
With the battery electrically a few feet away from the battery buses,
that tie the inverter
and charge controllers together (plus other components), the CCs and
other energy sources
can be momentarily short-circuited by the inverter (various reasons)...
If that bus was right at the battery terminals, then it's not nearly as
much stress on
things. This is because the battery keeps a low impedance voltage point
between
the two different systems.... This assumes that the batteries are in
decent health.
You probably won't notice any issues wiring just the way you have been
doing things
all these years so I would just keep doing what you are doing. With
proper over current
protection (OCP), stress and reliability won't be an problem.
But, it doesn't hurt to keep this concept in the back of your mind when
thinking about
how things work.
boB
On 10/31/2015 6:12 PM, Allan Sindelar wrote:
boB,
I appreciate your contribution to this discussion, but it brings up a
couple of issues for me.
- You have suggested that "A good wiring practice these days is
to...wire the controller's battery terminals close or right at the
battery terminals." This goes against all modern good practices of
which I'm aware. We have long accepted as standard a single pair of
battery cables, with all DC input and distribution handled within the
power center (I've heard that some people refer to these things as
'E-Panels'). It's the only way to effectively run all current through
a shunt on the negative, and through proper overcurrent
protection/disconnects on the positive.
I must not have understood what you meant, as it sounds like you're
suggesting abandoning the entire E-Panel approach. What am I missing here?
Thanks, Allan
*Allan Sindelar*
al...@sindelarsolar.com
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
*505 780-2738 cell*
**
On 10/29/2015 7:10 PM, b...@midnitesolar.com wrote:
On 10/29/2015 5:02 PM, Jay wrote:
boB,
Is the OCP still being used and does it work in both directions?
JAY, Peltz power
Hi Jay. Yes, the OCP you refer to is still there. This particular
OCP though is a hardware
fast OCP intended to protect the controller against large load surges
on the battery
side of the controller... This usually happens when battery cables
are long and
the inverter(s) are connected electrically close to the controller,
thereby drawing
huge amounts of current from the Classic than from the battery when
the inverter
is turned on, charging its input capacitors or something with huge AC
loads.
A good wiring practice these days is to, if convenient at least, wire
the controller's
battery terminals close or right at the battery terminals. Then, when
an inverter
is either turned on and giving a momentary short circuit to the
battery lines, that
current will come from the battery rather than the controller's
electronics.
Larger cables won't necessarily fix the problem due to battery
cable inductance.
The 150s and 200s rarely need the OCP circuitry. The 250 is the one
the OCP was
really designed for but we put it into all of the controllers.
There is also over current protection going the other way but is not
a microsecond
timed protection. Plain old fast or slow ramping up surges like
we're talking about is easy to
control, normally.
Breaker tripping like this is extremely rare, IF it is from this kind
of current spikes due to
generator startup. I would suggest to be safe and bring another
controller up just in case.
Might be a bad controller but I just don't know without logging or
observing it happening
with a scope and a current probe. I've seen some very strange things
happen.
boB
Sent from my iPhone
On Oct 29, 2015, at 4:19 PM, "b...@midnitesolar.com"
<b...@midnitesolar.com> wrote:
Larry, because these MPPT CC's are bi-directional (for
efficiencies' sake), they can convert a large current
at the battery side to a smaller current at the PV side if not
adjusted right. Normally this is just taken
care of and reduced to a bare minimum by the controller watching
the voltages and currents carefully.
It is technically possible though for things to not work exactly
correctly. I am not saying that this is
for sure happening, but it is possible. The ramping up in battery
voltage from the chargers should
be plenty slow enough for this not to be a problem but I am wildly
speculating that this could happen
and cannot rule it out. There may of course be something else
completely different happening here
though.
If CBI breakers are being used, these are known to be extremely
fast at tripping when overloaded.
Also, what, if any SPDs are connected to the system ?
boB
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