[RE-wrenches] grounding the Enphase inverter

[Mark Frye]

I guess the thinking is that DC side of the Enphase is grounded and
therefore a separately derived system requiring it's own system grounding.
This is achieved by connecting the GEC to the chassis of the inverter. If
the DC side of the inverter were ungrounded, then it would not be a
separately derived system and would not require it's own system ground. At
that point, would the AC side of the inverter still be considered a
separately derived system or would the need for system grounding go away?
 
Mark Frye 
Berkeley Solar Electric Systems 
303 Redbud Way 
Nevada City,  CA 95959 
(530) 401-8024 
 <http://www.berkeleysolar.com/> www.berkeleysolar.com  
 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Bill Brooks
Sent: Friday, March 04, 2011 5:51 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] grounding the Enphase inverter



The better question is why is there a solid ground in the inverter. 

 

As I stated before-we are talking about system grounding-with 100+ years of
electrical history and precedent to back it up.

 

System grounding rules are not open to a lot of discussion. That is why my
recommendation since before they released their first product was to go
ungrounded. Just because it is a pain, and we think there is no technical
reason, does not mean we can ignore the rules. As I said in my post, this is
not really a safety issue, but it is very much a compliance issue. System
grounding is so much a part of our electrical culture, that tiny electrical
supplies like PV microinverters were never really considered. 

 

Any installer can use the "don't ask, don't tell" method of installation,
but once we start down that path, the ability of the human mind to justify
actions is limitless. We have to go back to why we ground systems in the
first place. It is to prevent the voltage on the system conductors from
wondering too far from ground potential. There are other ways to prevent
this, but in the U.S. we mostly use conductors (not a variety of conductive
materials without clear ratings). The advent of the WEEB, with all its great
benefits, does not fundamentally change system grounding.

 

The sooner we get PV systems ungrounded, or resistively grounded, the better
the whole U.S. PV industry will be. To that end, everyone should move to PV
Cable/Wire and modules with PV Cable/Wire so we are using better products
than USE-2 and we can easily transition to ungrounded inverters as they
become more available. We already have several so now is not a bad time to
start thinking about it.

 

Bill.

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