Upgrading to a versatile Midnite or Outback cc seems to me a better investment.
Sometimes you can match newer 72 cells with older mods...For example, one new
Canadian 280 (35.6Vmp, 44.2Voc) matches up nicely with 2 old Kyo 120's
(33.8Vmp, 43Voc)....
Eric
SunHarvest
----- Original Message -----
From: Jason Szumlanski
To: RE-wrenches
Sent: Thursday, January 24, 2013 12:38 PM
Subject: Re: [RE-wrenches] 24V Module Query
I totally agree - old mods are usually not worth messing with at today's PV
prices. In some cases it might be best to downsize the system and then AC
couple some microinverters to cover the decrease in performance, or just
replace the entire array if there are enough problems. There is a used market
for smaller PV mods on Craigslist.
Back when I was installing Astropower 110W modules on single voltage Xantrex
C40's, I never thought we'd be using anything but 12V nominal PV mods. Little
did I know... Off-grid is really tough in these retrofit situations, but this
applies to failed/broken mods on grid-tie systems as well. That's where I can
make a good case for microinverters.
Jason Szumlanski
Fafco Solar
On Thu, Jan 24, 2013 at 3:11 PM, Ray Walters <r...@solarray.com> wrote:
Hi Allan;
I've been in the same conundrum lately. I found that AEE and others have
12 v modules (Solartech), but the price per watt is double or triple. My take
is that somewhere around 200 to 400 watts, its more cost effective to go to the
GT modules with an MPPT controller. Blue Sky makes the 1524, and 3024 that can
take up to 57 Voc, so those would work at still fairly low cost. Unfortunately
many of the other low cost MPPT controllers won't work with the 60 cell
modules. At some point, it may actually be cost effective to just use 60 cell
modules with non MPPT controllers, and just forget about the extra 24 cells.
(I know that sounds crazy, but PV less than $1/ watt is crazy too)
I'm trying to add modules to an existing array of 8 Siemens 12 v modules,
and it just doesn't work out, except with separate controllers.
Also, its amazing how much PV you can throw at an off grid project these
days for $10k.
It almost makes messing around with the old modules a waste of time.
Perhaps the solution might be to remove old arrays for customers wanting to
really up size, and then reuse the old modules for small systems?
Ray
On 1/24/2013 12:35 PM, Allan Sindelar wrote:
Wrenches,
We have years of installing 36-cell (12V) and 72-cell (24V) modules for
battery-based customers. Most of our systems are 24V or 48V nominal. Over the
last few years, sources of conventionally-sized 72-cell modules have dried up -
as cells have increased in size, most modules and most newer factory production
lines have either gone to 60-cell (20V) modules, or 72 cells in 300+ watt
ranges. It seems that the formerly common 72 cell, 24V modules in the 150-190
watt range, which are well-suited to integrating into existing systems, are no
longer available.
60-cell modules in the common 220-250 watt range can't be added to an
existing system unless run through a dedicated MPPT charge controller that can
convert voltage, such as an FM, XW60, Classic or TriStar; the added cost of any
of these controllers cancels out the low prices of the modules.
Who continues to manufacture 72-cell modules? Which distributors carry
them?
I am aware of three options - are there more?
- Sunpower makes one module in the 245 watt range that can be used
negative ground, but it's very high efficiency (and with high Voc/Vmp as well)
and very pricey;
- Sanyo/Panasonic has 225-240 watt modules, but also quite premium
and pricey;
- Ameresco bought the rights to manufacture many former BP modules,
and I think they make some. But we had to replace lots of failed BP modules in
that size range, and are hesitant to use their technology, fearing that the
problems may persist in the continued line.
Thank you for any discussion and recommendations.
Allan
--
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
Positive Energy, Inc.
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
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