I've checked several PV modules under load in past years and they all seem to do this.


Just cell mis-match I was guessing.

boB


On 5/17/2018 3:19 PM, Corey Shalanski wrote:
On a recent utility-scale PV installation we noticed a strange phenomenon on a single string on a single inverter. An IV curve (attached) reveals that the measured performance characteristics for this string (solid line) are significantly less than the expected values (dotted line). For reference, the ambient temperature was 31°C and the irradiance was 1010 W/m².

The phenomenon that more so caught our attention is apparent on a thermal image (also attached) of the modules in this string. For lack of a better term I would describe the distribution of cell temperatures as resembling a "checkerboard" or "scattershot" (random) pattern, ranging between roughly 55°C and 70°C. Interestingly this phenomenon was only apparent while the inverter was operating, i.e. with the inverter turned off the modules revert to a much more uniform temperature distribution nearer to 55°C, instead varying by only a couple degrees across the entire module/string.

There was no apparent physical damage to the modules.

Can anyone offer any suggestions about what might be causing this phenomenon?

--
Corey Shalanski
Joule Energy
New Orleans, LA


_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org


_______________________________________________
List sponsored by Redwood Alliance

List Address: RE-wrenches@lists.re-wrenches.org

Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive: 
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out or update participant bios:
www.members.re-wrenches.org

Reply via email to