Started by nigel, June 10, 2011, 12:22:29 PM

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Just a quickie on the MNSPD 115 DC surge protection device. Which would be the best place to mount and wire the unit.To the Midnite Solar MNPV6 combiner box or directly to the terminals of the FM60 charge controller ? The distance between the two is 4 meters about 13 ft

Regards Nigel



Typically it is best to mount it as far from the electronics as possible (IE at the base of a turbine or on a solar combiner box) although it will depend some on where you anticipate the surge coming from. The most common mounting spot I see daily is on the Epanel.
Changing the way wind turbines operate one smoke filled box at a time


i'm thinking the opposite here for putting it at the pvs the wire acts like an antenna and if so the emp or surge is free to travel to either end to be a low resistance short at one end and a low resistance load at the other with the cc electronics. that would only serve to split the surge's power distribution. if nearer the cc there is less chance of the smaller wire run to pick up the surge to send it to the electronics.

ryan and vic,
think of coax to ham antennas as they don't discourage doing the suppression at the antenna, but yhey state it to be mandatory before the coax enters the building because the wire in the coax picks up the surge too and gets sent to both ends, the antenna and radio equipment. antennas, like pvs, can take high surges fairly well, but it's the electronics at the other end in both solar and ham radio that is more vulnerable. i say, it doesn't hurt to put in one at both locations, but given a choice of putting in only one of them, i would put it closer to the cc.


OK In my case the solar panels are the roof of my cheese wedge solar power shed, the longest run from the PV to the MNPV6 is about 3 meters (10 ft) and the run from the PV combiner to the flexmax 80 is also about 10ft. So Im guessing put the MNSPD 115 on the combiner box ?

However my other tracked array is about 60ft from the Solar shed where would I put one in this case ? It has its own FM60  If Niel and common practice that Ryan mentioned it would be near to the FM60.

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if it were my installation the first one with the short run you can put it in the combiner box in my opinion as the wires are somewhat short. now the long run you have i would put one at the pvs and one somewhere at the other end of that 60ft run before the cc, but that's just me. if going with only one then before the cc is what i would do, but that also allows a good portion of surge energy to enter the building in some installs before being grounded out and this is probably ryan's thinking on placing it at the pvs far away. there's no law against using 2 spds and it's better protection using 2 in the case of such a long run with one at the pvs and one before the cc. before the cc means before the pv wires enter the cc and can be used on an epanel.

can i ask if you get thunderstorms where you are as that would be the worst case surge you'd likely experience barring a nuclear war?


Yes we get some good thunderstorms here, Ive had delta units fitted on ever thing for the last six years and as Ryan said always as close to the product being protected. Only replacing the main Xantrex SW inverter with a complete Outback Flexpower One earlier this year, which has its own Surge protection device but I dont thik it protects the FM80, just AC side in and out.
I am lucky that in the valley below me some 400ft away we have a electric and normal railway line and I expect they have added to my survival. However I am aware that many people have lost equipment in my area through electric storms,  but I also come across lots of off grid installations with little or non existent earth (grounding circuits)

As a installer and retailer I just like to follow best practice it wont be hard for me to sell the New MNSPD as there cost in relation to the products they are protecting it is a good investment.