[RE-wrenches] strings of older solar panels

[Matt Lafferty]

Lee,
 
They are good to go @600V. Depending on vintage, they may be configurable
for 6 or 12 Volt in the J-box. You might want to consider going the 6V route
and only using 1 string. This would serve to keep your string voltage "up"
if you lose a module or two down the road. Either way, as mentioned by Brian
T below, make sure you have the diodes.
 
Allan's comment about IV characteristics is something to watch for and
document BEFORE you get too far into any conversion effort. Remember, once
you touch it, you're the bad guy if the customer isn't getting what they
think they should out of it.
 
As far as "on the Go Solar California list".... The list requires additional
testing (and certification) compared to earlier vintages. Most legacy
modules are no longer listed here.
 
Pray for Sun!
 
Mutt Lafferty  
  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Wednesday, November 18, 2009 11:04 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] strings of older solar panels



Lee,

Note also that the MSX series was known to have some defective modules. They
showed correct Voc and Isc but essentially a flat I/V curve slope, meaning
very weak output; that was a real headscratcher for installers. I had a set
of 12 from around 1994 with this behavior. Solarex never recalled this bad
series, but I heard about it from another old-timer. Solarex replaced all of
mine under warranty, but warranties back then were 10 or 12 years, so by now
expired. Of course, back then there was a Solarex. But they knew which
serial numbers were prone to be defective.

 

I would encourage you to test array output before putting any effort into
making it a GT system. If these are low output, push hard on BP(?) to cover
them as known to be defective. 

 

Allan Sindelar

Allan at positiveenergysolar.com

NABCEP Certified Photovoltaic Installer

EE98J Journeyman Electrician

Positive Energy, Inc.

3201 Calle Marie

Santa Fe, New Mexico 87507

505 424-1112

www.PositiveEnergySolar.com <http://www.positiveenergysolar.com/> 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Brian
Teitelbaum
Sent: Wednesday, November 18, 2009 11:33 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] strings of older solar panels

 

Lee,

 

I also have an old spec sheet for the MSX60/64 that does not state the max
system voltage. It does, however, state that it passes a 2700VDC frame/cell
isolation test. I don't know if that is the required test for a 600VDC
rating or not.

 

If I remember correctly, they were not sold with bypass diodes installed, so
if you do use them in a system above 24V, be sure to add the diodes.

 

Brian Teitelbaum

AEE Solar

 

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Solar Plexus
Sent: Wednesday, November 18, 2009 9:33 AM
To: RE-wrenches at lists.re-wrenches.org
Subject: [RE-wrenches] strings of older solar panels

 

Hi Wrenches.

 

            I have a customer with 32 of the Solarex MSX-64 solar panels an
a battery-based system.  He wants to go batteryless inverter.  So I am
looking at  2 strings of 16 in series.    But the solar panel spec sheet
doesn't say anything about system voltage rating.  Can I do this?

             If  one solar panel in the string is shaded, does it see the
full string voltage of around 280 volts?  Is there something in the way new
panels are made that makes them more able to handle this voltage, or is it
just that they are now tested for it?

            My guess is this request may be happenning a fair amount.  Is
there a reason these panels are not listed on the California GoSolr website?

 

Lee Tavenner

Solar Plexus

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