Kaneka GSA? (series fuse and details) [RE-wrenches]

Wed Aug 16 18:36:29 PDT 2006

Travis,

The Kaneka 60 watt series fuse rating from the back of the module is 5A
maximum.

As a technical support person for a potential distributor of the Kaneka
modules, I was assigned to evaluate the module and installation details.
I had a lot of questions too and have had a team of Kaneka engineers
come to my office to address them. 

In general, the Kaneka is single junction amorphous cells on a thin
float glass substrate bonded to a tempered glass top layer. The Kaneka
is unique in that each cell is about 5/16" wide and runs the full height
of the module. This means you can install modules in E-W rows and place
the rows close together N-S. The lower edge of the modules in rows 2 and
back can be shaded with no deleterious effects. I have talked with
Kaneka engineers about this and they said it was fine. Obviously the
module puts out less power when shaded because the cells are effectively
smaller, but you have only a linear loss of power instead of the
exponential loss of power from shading a portion or a row of crystalline
cells. 

There are some quirks about the Kaneka that are not readily apparent.
Most of them have to do with the "non-American" way the instruction
manual is written. The Kaneka engineers are very concerned about peak
performance of the modules. They are very concerned about quality and
reliability, but in a very Japanese way. Therefore they wrote in the
instructions & warranty the forbidden things that "produce deleterious
performance of the module" like don't mount the module at tilt angles of
less than 5 degrees (When you ask them it's because the dirt builds up
on the bottom edge and puddles of water would focus light on specific
areas of the module), don't let snow build up, etc. When you read the
instructions it raises a bunch of red flags. However, when you talk to
the engineers, their concerns are not any different than any other
module manufacturer would have to maximize power output. The biggest
limitation is the high voltage per module 92Voc and the 530V open
circuit maximum voltage. The modules were tested to 1000V but since they
are conservative and someone said strings of 5 in series at -25C was
530V, they UL listed it at the lower voltage. From what I have been
told, it was not UL mandated to be 530V, just chosen to be. This has
been an agitation for me but I have made no headway in getting them to
raise it to 600V for colder climates.

The cells run from top to bottom of the module. The module has only one
orientation. The bottom edge is specifically the bottom edge because it
has two small notches to let water pass out helping to eliminate the
dirt buildup on the bottom edge. The installation manual specifically
prohibits mounting it landscape orientation because any dirt buildup
would cover one complete cell and would seriously reduce performance. 

Another issue I have discussed with the Kaneka engineers is how to
reduce the number of series fuses in the system. Though these modules
are significantly cheaper than crystalline modules, the 92Voc limits you
to series strings of only 5 per NEC in most locations, 4 in cold
climates <-25C. That means a lot of wiring. The fuse rating on the
original model number GSA-221 is 5A, but the internal bussing is rated
for 7A. A previous post from Brad @ AEE referenced a Kaneka datasheet
showing a 7A fuse rating. Since 1.56 x Isc of 1.19A = 1.86A, the minimum
fuse for one string is 2A. You can put two strings in series with MC
Y-connectors and then use a 4A series fuse. This will keep a short in
the bussing from seeing more than 7A (i.e. <2A from the paralleled
string plus 4A via the fuse is less than 7A, with <2A coming through the
bussing on the opposite side of the short). You can't parallel more than
two strings prior to a fuse.

According to independent Japanese University field testing, the Kaneka
amorphous modules will collect about 8% more energy annually than the
same STC watt rating of single crystalline modules, about 13% more than
poly. This is due to the lower temperature coefficient of power and the
annealing process of the amorphous cell when exposed to higher
temperatures. The coefficient of power is 0.19 compared to 0.38-0.40 for
crystalline cells, therefore you lose less power in the hotter climates
(you would also gain less power in very cold climates). When the
amorphous cell temperature gets above about 130+ degrees F for about 100
hours, the power output actually increases. You can actually see this
summer power increase on an annual graph if you have a data logging
system. In the colder winter months, the annealing goes away and the
power output drops back down.

This should help some (and maybe raise some more questions).

Aaron Wellendorf

DC Power Systems

707-433-5824 x121

-----Original Message-----

From: Travis Creswell, Ozark Solar [mailto:ozsolar at ipa.net] 

Sent: Monday, August 14, 2006 4:17 PM

To: RE-wrenches at topica.com

Subject: Kaneka GSA? [RE-wrenches]

Can someone tell me what the "series fuse" rating of the Kaneka 60 watt

module is?

Any comments on this module would be welcome.

Thanks in advance,

Travis Creswell

[Non-text portions of this message have been removed]

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