Surface polarisation [RE-wrenches]

[John Berdner]

Carl/Wrenches:
 
All of the US series Sunny Boy inverters have field selectable ground
polarity.
You can choose either negative grounding or positive grounding
depending on the needs of the particular module you are using.
All that you need to do is set a simple jumper and place the GFDI fuse
in the proper holder.
 
For the Rest of World inverters that normally run "ungrounded" SMA in
Germany does have a kit to establish ground polarity.  The ROW inverters
normally run with a high impedance ground reference that effectively
floats the array centered around ground.  The kit can be used to create
a positive ground reference were needed but you lose the real time
monitoring of ground leakage current.
 
Best Regards,
 
John Berdner
 


>>> freepower at freepower.co.nz 11/18/2007 03:43:59 PM >>>


Hi gang,



I came across this article that suggests positive earthing of systems
will
improve performance in some cases. I understand that SMA has developed
a kit
to facilitate this having acknowledged the performance advantages.



Text of a technical comment follows.



=============================



SunPower has announced it has discovered a new performance effect it
calls
'surface polarisation' in high-efficiency silicon solar cells. Surface
polarisations create the non-destructive and reversible accumulation
of
static charge on the surface of high-efficiency solar cells, it said.
The
effect occurs when minute amounts of electrical current leak through
the
face of the solar cell and accumulate on the surface. SunPower said it
found
that electricity production in systems that use high-efficiency solar
cells
could be significantly decreased or increased by varying the system
wiring
and grounding configurations. As the result of the company's
discovery,
SunPower scientists have developed and applied for patents on new solar
cell
and system designs that eliminate surface polarisation.

=============================================================



A more detailed discussion is found here... 



www.solarsales.com.au/download/SunPowerPolarizationHandbook.pdf 





Guys, this is said to effect Back Contact and Thin Film modules.

I have found no hard data on the performance advantages, can someone
comment
on this ??



Thanks,



Carl Emerson

Free Power Ltd.

Auckland


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