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<p><br>
</p>
The SPD-600 is evidently the one to use on the SMA TL inverters.<br>
<br>
In older grounded PV systems, if the negative or positive is
grounded directly to ground, then you could get by without<br>
an SPD connected to that grounded conductor because it is, well,
already grounded and that line will rise in voltage along with<br>
the ground voltage from the strike. However, if this grounded PV
conductor is connected through one of the r ground fault
interrupters <br>
that has a 1/2 amp or slightly higher ground bonding connection,
(not permanently bonded), like the Classic or MPPT-60 and<br>
some other controllers with internal GFIs then I would think that a
separate SPD line be used for positive and negative PV lines on that
array.<br>
We don't want that ground bond to open on that line and risk
internal arcing in the equipment.<br>
<br>
As for arc faults, SPDs are a passive type protector and should not
make any noise that might be interpreted by the sensor as arcing.<br>
Lightning itself may very well be interpreted as an arc. I think
that the Bird-House system which has a switcher supply up-stairs<br>
in the Bird-Next might have been an arc fault culprit for some TL
inverters. Sometimes it is hard for a AF detector to tell the<br>
difference. Hopefully they are better now.<br>
<br>
"I have clients who have covered the SPD's in tape to keep the light
from attracting small flying insects to the electronics area. "<br>
<br>
I hear you there, Dave ! We are working on being able to coordinate
the lightning strike with the insects so that the SPD also<br>
works as a bug zapper ! :) <span class="moz-smiley-s1"><span>:-)</span></span>
<br>
Just kidding...<br>
<br>
boB<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 10/9/2018 3:10 PM, Dave Angelini
Offgrid Solar wrote:<br>
</div>
<blockquote type="cite"
cite="mid:e5c18726138503324bff50e197aac59e@127.0.0.1">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<p>We have been using Midnite SPD's since they came out. The one
suggestion I have is the light is too intense. I have clients
who have covered the SPD's in tape to keep the light from
attracting small flying insects to the electronics area. Some
places just have too many bugs :( The blue seems to bring them.
I saw an inverter fan filter that was an 1/8 of an inch thick
with gnats.</p>
<p>Fly paper will help but the battery circuit and AC panel SPD's
need some help here.</p>
<pre><strong><span>Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a href="http://members.sti.net/offgridsolar/" target="_blank" moz-do-not-send="true">http://members.sti.net/offgridsolar/</a>
e-mail <a href="mailto:offgridsolar@sti.net" moz-do-not-send="true">offgridsolar@sti.net</a>
text 209 813 0060</span></strong></pre>
<p> </p>
</blockquote>
<br>
<br>
<br>
" boB,
<p> To add to Drake's wonderings, I've had a few SMA
TL-40 inverters trip with an AFCI fault. Significant hassle to
get onsite and deal with it. Some with metal roofs some without,
may have been lightening in the area.</p>
Bill "<br>
<br>
<br>
<br>
<br>
<blockquote type="cite"
cite="mid:e5c18726138503324bff50e197aac59e@127.0.0.1">
<p>On Tue, 09 Oct 2018 17:02:32 -0400, Drake
<a class="moz-txt-link-rfc2396E" href="mailto:drake.chamberlin@redwoodalliance.org"><drake.chamberlin@redwoodalliance.org></a> wrote:</p>
<blockquote type="cite" style="padding-left:5px;
border-left:#1010ff 2px solid; margin-left:5px; width:100%"><!-- html ignored --><!-- head ignored --><!-- meta ignored -->Hi
boB,<br>
<br>
I will keep putting an SPD on each string and on the AC line.
Sometimes my systems end up with a lot of blue lights hanging
from a wiring gutter!<br>
<br>
Have you ever heard of any problems using the Midnite SPDs with
Sunny Boy TL series inverters? So far, I don't think I've had a
problem, although one TL-22, on a large metal roof, had arc
fault protector trips. <br>
<br>
Thanks,<br>
<br>
Drake<br>
<br>
<a name="_MailAutoSig" moz-do-not-send="true"></a>Drake
Chamberlin<br>
<em>Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV <br>
740-448-7328<br>
</em><a href="http://athens-electric.com/"
moz-do-not-send="true">http://athens-electric.com/</a> <br>
<br>
<br>
<br>
At 01:39 PM 10/9/2018, you wrote:<br>
<blockquote class="cite">Content-Type: multipart/alternative;<br>
boundary="------------98C0DCEF93B9ECF248E0580B"<br>
Content-Language: en-US<br>
<br>
<br>
For an inverter with two MPPT inputs, you will need to treat
the negatives and positive lines separate unless<br>
the manufacturer says something else. That means one SPD per
array unfortunately. Negative and positive connect<br>
to separate leads of the SPD and then ground in the middle.
As both positive and negative PV lines rise together<br>
relative to ground, the SPD is supposed to clamp that rise to
below the equipment's hi-pot voltage that they test<br>
to at the factory. (i.e. common mode voltage rise) All wires
except for ground (chassis) of the equipment are tied <br>
together and the hi-pot machine (sort of like a Megger ?)
applies the high voltage between all those wires on one <br>
side and ground on the other to make sure the insulation
doesn't break down inside the equipment. <br>
This hi-pot test goes for AC utility input/output connections
and DC from the PV input side. <br>
<br>
The SPD has to clamp plus and minus and AC inputs to a lower
voltage than this hipot rating but higher voltage<br>
than lines will see differentially in voltage. Remember that
in a 3-wire SPD, there is two sets of MOVs in series and<br>
the center is tied to ground. If one MOV starts conducting at
say, 500 volts DC then you can apply up to 1000<br>
volts between the hot leads. Each plus and negative line can
rise up to 500 volts from the lightning before they<br>
start to clamp. The bigger the lightning strikes effect, the
more current will be applied to the MOVs though and<br>
the clamp voltage will rise somewhat. That's why the SPD
arrestor voltage should be well below the hi-pot voltage,<br>
whatever that is... Hi-pot voltages are quite a bit higher
than the operating voltage. For example, All Classic CC's<br>
are tested to 2270 volts DC from hot lines to ground. It's
something like double the operating voltage plus 1000V<br>
and multiply by 1.414 for DC rating..... I'm going off memory
so don't quote me on that but something like that.<br>
<br>
I think that Ray has the right idea about short connections
like from the local generator. Battery also.<br>
Just apply SPDs to anything that goes outside like an antenna.<br>
<br>
boB<br>
<br>
<br>
On 10/9/2018 8:26 AM, cwarfel wrote:<br>
<blockquote class="cite"><br>
<span style="font-family: Verdana;">I think something on the
order of 90+% lightning strikes come from the utility
feed, not the dc side. That has to be ignored if in a high
strike area or grid isolated. </span><br>
<br>
On 10/8/2018 10:37 PM, Ray wrote:<br>
<blockquote class="cite"><br>
I believe you can use the SPD 300 AC on 2 strings, if PV
neg is grounded. You would connect the green to ground
(or PV neg) and then connect the red to one string pos,
and connect the black to the other string pos. This would
be limited to 300 v also. I haven't tried that exact
configuration, but I have used the 300 AC to protect both
the AC in and AC out on 120 vac inverters. I also believe
you can use a 600 DC version, and wire as I mentioned, but
the LEDs won't light. If you are using ungrounded
inverters, then I think you would need an SPD for each
string in order to protect both the pos and neg of each
string, like you've been doing.<br>
<br>
Maybe someone from Midnite can clarify this.<br>
<br>
As far as it being worth it, I haven't had lightning
related damage since I started using the Midnite SPDs, and
I used to have system damage every year. If you are not
in lightning country, or the install is in a low spot with
less likelihood of taking a hit, you might be able to
skimp. But for some of these off grid ridge top installs,
I consider it a must. Some times I don't install one on
the gen circuit, if its really close.<br>
<br>
<br>
<br>
<pre>Ray Walters
Remote Solar
303 505-8760</pre>
<span style="font-family: 'Courier New', Courier;"></span>On
10/8/18 4:03 PM, Drake wrote:<br>
<blockquote class="cite">Hello Wrenches,<br>
<br>
Do you use surge arrestors with multi MPPT input string
inverters? Do you put a separate arrestor on each MPPT
input? I find it sort of pricey using a Midnite Solar
arrestor on each string, but have been doing that. Is
there a less expensive approach that is effective? <br>
<br>
I believe the Midnite units are the best. Are they worth
the expense?<br>
<br>
Thank you,<br>
<br>
Drake<br>
<br>
<br>
<a name="_MailAutoSig" moz-do-not-send="true"></a>Drake
Chamberlin<br>
<em>Athens Electric LLC<br>
OH License 44810<br>
CO License 3773<br>
NABCEP Certified Solar PV <br>
740-448-7328<br>
</em><a href="http://athens-electric.com/"
moz-do-not-send="true">http://athens-electric.com/</a>
<br>
<br>
<br>
<br>
<br>
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