[RE-wrenches] Surge arrestors on strings

[cwarfel]

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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-- 

 Â Â Â Â Â Â Â Â  Christopher Warfel, PE
 Â Â Â Â Â Â  ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
 Â Â Â Â Â Â Â Â Â Â Â Â Â Â  (401)466-8978

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