Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-21 Thread Dave Tedeyan
Hi Corey, I recently commissioned a large system and saw something very similar. Is it possible that there is a minor amount of shading on those modules? Maybe weeds growing up or powerlines? When I had noticed that cell pattern, it took a little bit to realize that there were powerlines just

Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-18 Thread Bill Hoffer
Corey I consulted and did some independent tests with a module manufacturer who had some modules with low Power output and curve traces similar to yours. They however could detect no abnormal cracks in the modules with EL testing. I also detected no issues on the thermal image at no or low power,

Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-17 Thread Dave Angelini Offgrid Solar
Corey, What make of panel please. Forgive if I missed it... Dave Angelini Offgrid Solar "we go where powerlines don't" http://members.sti.net/offgridsolar/ e-mail offgridso...@sti.net text 209 813 0060 > Corey, > > I have been studying IR diagnostics quite a lot, but I haven't had a whole >

Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-17 Thread b...@midnitesolar.com
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

Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-17 Thread Kienan Maxfield
Corey, I have been studying IR diagnostics quite a lot, but I haven't had a whole lot of opportunity to "get my hands dirty" with it, so I'm not sure how much help I'll be. I would like to know how many modules are in each string. I'm going to share some random thoughts on this, but nothing

Re: [RE-wrenches] PV Cell Temperature Variation

2018-05-17 Thread Mike Kocsmiersky
A dampening of the knee of the IV curve would be indicative of higher series resistance. The higher series resistance would also increase cell temperatures as shown in the thermo image. The cooling off of the cells under open circuit conditions would also correlate to the higher series