[RE-wrenches] Surge arrestors on strings

[Ray]

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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