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*
[email protected]_ <mailto:[email protected]>
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_ <http://www.positiveenergysolar.com/>
*
*
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