Geoff,
When you mentioned "plenty of partial shading", that settled the issue
for me. Every cell in Uni-Solar modules have a bypass diode allowing
them to handle shading better than any other module I know of. For
potentially shaded areas or high ambient temperatures, it is our
module of choice. After 6 years of selling and installing Uni-Solar,
we have only had one failure. Their performance here in our very hot
climate is outstanding.
As for the mismatching module sizes, the 68 is half the voltage of the
136 but the same current. They both use the same cells. If you are
only using a single string the MPPT controller will simple adjust for
the Vmp of that circuit. However, as with any array, if you have
multiple strings with mismatched string voltages, the controller will
"see" a lower average and you will, at the least, be wasting power.
The bypass diodes have nothing to do with mismatched strings.
If you are comparing arrays with different angle of incidence and
without shading, the one most perpendicular to the sun will perform
the best.
Kindest Regards,
Larry Crutcher
Starlight Solar
11279 S. Glenwood Ave #11114
Yuma, AZ 85367
(928) 941-1660
[EMAIL PROTECTED]
www.starlightsolar.com
On Oct 31, 2008, at 8:08 AM, Geoff Greenfield wrote:
As a follow up to my uni-solar post (and thanks to all who provided
feedback), I have a second request:
Any references to recent side-by side "shoot-outs" between Unisolar
and conventional crystaline PV? Scientific studies? Your own
wrench thoughts?
I am more and more often encountering confused customers that are
considering unisolar systems at zero-tilt (we are at 40 degrees N),
with plenty of partial shading, after getting a pitch about all
sorts of advantages of Uni-Solar. I think that this product has
it's role and I occasionally sell it... But I am frustrated when I
truly believe I can deliver a better net energy production with a
tilted crystalline solution (avoiding the shaded areas).
For a brighter energy future,
Geoff Greenfield
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
