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 orgrid isolated.
On 10/8/2018 10:37 PM, Ray wrote:
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.
Maybe someone from Midnite can clarify this.
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.
Ray Walters
Remote Solar
303 505-8760
On 10/8/18 4:03 PM, Drake wrote:
Hello Wrenches,
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?
I believe the Midnite units are the best. Are they worth the expense?
Thank you,
Drake
Drake Chamberlin
/Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV
740-448-7328
/http://athens-electric.com/
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