Allan and Brian
Thanks for the answer to the problem. I think the Xantrex PWM
chargers are going to be the most appropriate for these modules.
The old Arco modules are incredibly long lasting. I hope the ones we
are putting in today will last as long.
Drake
At 01:40 PM 3/20/2009, you wrote:
Drake,
Just to add to Allan's excellent post, most of the Arco's made
before about 1985 had less than 36 cells. Some were 35-cell, most
were 33-cell, but there were also 32 and 30-cell units.
You might want to look into rewiring the modules in higher voltage
series strings to get more "oomph" out of the MPPT controller, and
reduce transmission losses. However, be aware that many of those old
Arco modules had a sticker on them that said something like "do not
operate above 50VDC"
I still have 12 Arco, 33-cell, model 16-2000 modules (16Vmp/2A) on
my off-grid house, wired in pairs for 24V and going through an
ancient Trace C-30A relay controller (not even PWM!). I've
contemplated wiring them for 36V and using MPPT, and I may someday,
but they have been working so well as is that I haven't bothered.
Even on hot days I often see 27.5V and 11-12A charging my 24V
battery bank, which I think is damn good performance from a set of
27-year-old modules.
Brian Teitelbaum
AEE Solar
-----Original Message-----
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allan Sindelar
Sent: Friday, March 20, 2009 8:32 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Sunpower modules
Drake,
The key to your question may be in the "old Arco units". Most Arcos (all
predate 1990, when Siemens bought Arco) are 36 cell, but both Arco and
Solarex made some 33-cell, 32-cell, and even 30-cell "self-regulating"
modules in those years. With fewer cells, the MPPT was too low to benefit
much from Boost technology.
I have one customer with Arco M52L "Tri-Lams" and another with 32-cell
Solarexes. In both cases I had recommended upgrade to MPPT, but when I saw
what modules they had, I told them not to go ahead with the upgrade, as it
wouldn't be cost-effective.
Allan Sindelar
allan(at)positiveenergysolar.com
NABCEP Certified Solar PV Installer
Positive Energy, Inc.
3201 Calle Marie
Santa Fe NM 87507
505 424-1112
www.positiveenergysolar.com
Please consider the environment before printing this e-mail.
-----Original Message-----
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Drake
Chamberlin
At 09:46 AM 3/20/2009, you wrote:
>The CTI-90, rated at 5.15 amps, will reach 7 amps here in Yuma with
>the Blue Sky 3024i.
Do you use the Blue Sky metering, or have you checked the MPPT output
with independent metering? I retrofitted a 12 V Blue Sky charger on
an old cabin system. The CC had no on-board metering. My measured
result showed almost the same output and input on a cool, sunny
day. The modules were ancient Arco units, but I still expected some
improvement.
Drake Chamberlin
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648
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