[RE-wrenches] 1000V System Wiring Details

August Goers august at luminalt.com
Mon Mar 31 09:54:25 PDT 2014


William -

I can't argue with the fact that all else being equal it is best to have
the inverters in an easily accessible location. I guess it is just a cost
benefit (and risk) analysis of the reduced cost to install them on the
roof versus on the ground for any given job. I agree with the general
sentiment that many installers are cutting upfront costs at the expense of
serviceability and oftentimes also not making good workmanship choices.

Best,

August

Luminalt

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
Miller
Sent: Friday, March 28, 2014 10:21 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] 1000V System Wiring Details

August:

Most commercial jobs we work have a vertical ladder through a roof hatch
or a vertical enclosed exterior ladder.  Being vertical they are not
comfortable to climb, so we immediately set up a ladder outside.

A fair portion of our work is repairing faulty installs. We always seem to
find a compelling reason to take the inverters off the roof. The last two
jobs were SMA upgrades from 2599s to 5000us inverters which don't fit on
the back of a low rack. This is why these units are coming off and this
was fresh in my mind when I saw your post.

Something about making the parts most likely to fail less accessible seems
counterintuitive to me.

William

Miller Solar

> On Mar 27, 2014, at 7:06 AM, August Goers <august at luminalt.com> wrote:
>
> Hi William,
>
> I should have clarified that I was speaking about commercial system
> with the Sunny Tripower or Power-One Trio type 1000 V string
> inverters. Many commercial roofs have stairwell access which makes
> getting the inverters up and then later servicing them relatively
> easy. But, yes, we have also used lifts to get inverters on the roof
which does add an expense.
> Typically we get the inverters up with the same equipment that we use
> to lift up the modules and racking as you mention below. There is the
> potential maintenance cost issue down the road if they need to be RMA'd.
> Mostly I think it makes sense for larger commercial systems.
>
> Best,
>
> August
>
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
> William Miller
> Sent: Wednesday, March 26, 2014 9:15 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] 1000V System Wiring Details
>
>
> August:
>
> What about the expense of servicing and/or replacing roof mounted
> inverters?  There is a very finite limit on the weight that is
> practical/legal to haul up a ladder. Sure it's easy to toss an
> inverter on the roof at the install when there is already a lift in
> the budget to hoist the PV.  Later on your crew might be tempted to
> slide a replacement inverter up the ladder, but this is not always safe
or OSHA legal.
>
> It's at least $400 to bring a scissors lift and a reach lift is about
> $600. Is this really good economics / safety practice?
>
> William
>
>
> Miller Solar
>
>> On Mar 26, 2014, at 7:31 PM, August Goers <august at luminalt.com> wrote:
>>
>> . Going forward, we are going to strive to put inverters on the roof
>> to
> minimize the expense of dealing with the 1000 V runs.
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