Author Topic: Enphase & MNSPD-300-AC  (Read 130 times)

skullz

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Enphase & MNSPD-300-AC
« on: May 02, 2022, 02:08:00 PM »
I am installing 4 branches of 10 panels for a total of 40 panels on a ground mount array using IQ8 microinverters.

The array is about 150ft away from where I wanted to mount the Enphase AC combiner box. Is that to far away for the MNSPD-300-AC to protect the microinverters?

My other thought was buy 5x MNSPD-300-AC and install one at the junction box for each branch and also one inside the combiner box but this seems like overkill.

Please advise.

boB

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Re: Enphase & MNSPD-300-AC
« Reply #1 on: May 02, 2022, 03:39:13 PM »

That is a good question....   Would be nice to have the SPD somewhere closer to the microinverters but if 150 ft is as close as you can get them, then that will have to do.

I wonder what Enphase has to say about this ?   The SPDs purpose of course is to try and keep the "common mode" voltages on the lines from inducing voltages high enough to break over the insulation of the components inside the microinverters.   That voltage would be somewhat determined by the voltage that Enphase uses to hipot their microinverters at.  Since the PV voltages aren't all that high, I would think that voltage might be around 1500V or so, L1/L2  and PV lines to GND.   So an SPD-300 should be fine for that.

I suppose these microinverters do have neutral or GND connected ?  Are they 240VAC microinverters ?

How close is it to the ground rod or ground connection from the inverters ?

boB
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skullz

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Re: Enphase & MNSPD-300-AC
« Reply #2 on: May 02, 2022, 04:12:37 PM »
Enphase microinverters are 240VAC with NO ground or neutral.

From one of their manuals:
"The Enphase IQ Microinverter system uses a new and improved cabling system. The Q Cable is DG type and contains only two #12 AWG line conductors. The Q Cable male connectors plug directly into the IQ Micros, whose double insulation rating requires no neutral or ground conductors. This lightweight cable drives down system costs while simplifying installation."

As for my grounding, I am using Ironridge rails with their bonding hardware. So the array frame, rails, and panels are definitely bonded.  My guess is that IQ8 get its ground from it mounting plate in this picture (can't find anything that says that).

FYI, this is a new install that I am planning, I will be installing two new ground rods installed one at the array and one at the MCP (100year old home it could probably use a new one...)
« Last Edit: May 02, 2022, 04:14:21 PM by skullz »

boB

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Re: Enphase & MNSPD-300-AC
« Reply #3 on: May 03, 2022, 01:18:03 AM »

Well then...  The SPDs might be more useful for your house AC appliances then and if that is the case, putting the SPDs 150 feet away might be just fine then.  I do not think that mounting bracket connects to anything...  But I don't know for certain.

I wonder what Enphase or any microinverter manufacturer has to say about this ?

boB
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