SunSlate Roofing [RE-wrenches]

Bill Brooks billbrooks7 at earthlink.net
Tue Mar 20 14:29:20 PST 2001


Marco,

Now your going to get me in trouble. I guess I'll take them in order.

Completely coating the junction block with silicone RTV was the solution to
pass the test. This does make dismantling more difficult.

I did notice that Trace Tech (on the Trace Eng. website has high voltage
combiners. I talked with UL and they said they've been approved for about
four months now, but just recently started selling them.

The ST claim about 8%--Do I have to answer that one. Here is my unbiased
assessment. All properly installed crystalline PV arrays have a reasonably
high fill factor (sharp IV curve characteristic). Polycrystal is less sharp,
but still significant. The ST was originally designed for the EPV a-Si
module, then redesigned for the BP Solarex Millenia a-Si module and that is
what it was tested on at PVUSA. I believe Trace when they say it works fine
on a-Si.

However, a crystalline array will have a tough time, especially in cooler
weather when the fill factor is better. This is an endemic (25 cent word)
problem with the way the original software max power tracks. All properly
installed crystalline arrays operating at an ambient temperature of (let's
guess) 60 F and less will have this problem from time to time. I don't see
how something in software could make this a hit or miss situation.

My experience in California tells me that well over 50% of our PV arrays
fall into the category I have listed above from time-to-time. My guess is
that if you camped out with these inverters on crystalline arrays in cooler
weather that every one of them would exhibit tracking problems. How can you
tell? You have to constantly monitor dc voltage and AC power to be sure.
Most people will only catch it making the mistake occasionally. Thank
goodness this will be a standard feature change and not an occasional field
fix.

Bill.


> -----Original Message-----
> From: mmangelsdorf at hei.com [mailto:mmangelsdorf at hei.com]
> Sent: Tuesday, March 20, 2001 12:15 PM
> To: RE-wrenches at topica.com
> Cc: sburns at hei.com
> Subject: RE: Unisolar Roofing [RE-wrenches]
>
>
> Bill,
>
> Thanks for the heads-up.  No, we didn't take heroic measures due to the
> PAUCITY of prior knowledge of needing to do such a thing...Guilty as
> charged, your honor!  Since it's a small system, we can check the j-blocks
> every so often to see whether invasive moisture is doing
> dastardly things to
> the wire connections.  So, the only solution that you found was
> to goop the
> heck out of the blocks?
>
> On another note, you did hear that Trace Tech. now has high voltage,
> UL-listed combiner boxes?  Regarding the SunTie tales of woe, what's your
> impression of their recent technical service bulletin?  And the part that
> talked about a failure rate of 8 percent of the STs in the field?
>  Based on
> the comments from the wrenches list, one would think that the incidence of
> MPPT problems and frequent cut-outs was higher than a little ole 8 out of
> 100.
>
> aloha,
> marco
>
>
> Marco,
>
> Did you take any heroic measures to seal the junction blocks on the
> SunSlates? Your systems are the first that I am aware of in a Tropical
> climate. I am very interested in the long-term (first year) reliability of
> the product in your climate.
>
> The product had a terrible time passing our field wet resistance test and
> the final solution was to silicon over all the junction blocks.
> This was the
> only thing they could do to pass the test. This tells me that unless you
> went to that extreme, you are likely to have problems in your
> climate. Keep
> checking your ground-fault protector.
>
> It is good to know that the installation went well after the first couple
> installs. It still must be more labor intensive than stand-off
> mounting, but
> many people like the looks.
>
> Bill.
>
>
> > -----Original Message-----
> > From: Jeffrey Wolfe, Global Resources [mailto:global at sover.net]
> > Sent: Monday, March 19, 2001 7:27 PM
> > To: 'RE-wrenches at topica.com'
> > Subject: RE: Unisolar Roofing [RE-wrenches]
> >
> >
> > Hi Marco,
> >
> > If you have an electrical problem after installation, how do
> you find it?
> > And when you find it, how hard is it to replace the slate? I
> used to work
> > in a roofing company that did some real slate work, and I'm
> > having trouble
> > envisioning this as being an easy troubleshooting and repair job.
> >
> > Jeff
> >
> > Jeffery D. Wolfe, P.E.
> > Global Resource Options, LLP
> > A Woman-Owned Vermont Limited Liability Partnership
> > 4 Kibling Hill Road
> > P.O. Box 51
> > Strafford, VT 05072
> > 802/765-4632
> > 802/765-9983 (Fax)
> > global at sover.net
> > http://www.globalresourceoptions.com
> >
> >
> > ----------
> > From: 	mmangelsdorf at hei.com[SMTP:mmangelsdorf at hei.com]
> > Reply To: 	RE-wrenches at topica.com
> > Sent: 	Monday, March 19, 2001 4:33 PM
> > To: 	RE-wrenches at topica.com
> > Subject: 	RE: Unisolar Roofing [RE-wrenches]
> >
> > <<File: ATT00003.htm>>
> > Holt,
> >
> > Having recently installed a Sunslates system here in Hawaii, I
> > can tell you
> > that they're not difficult to install.  The first system or two will be
> > kinda slow.  But once you get the procedure down, they go up fairly
> > quickly,
> >
> > marco
> >
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 RE-wrenches at topica.com

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 www.homepower.com

For info contact list moderator by email:
 michael.welch at homepower.com

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