Help! Solar panel dropping voltage by half when it warms up

[Traverse01]

Hello all,
Need some help with my 160 flexible solar panel mounted to my van roof. It was working great until last week when I started getting a 8.6-8.7v reading. I took apart the junction box and swapped the diodes. It will get normal volts in the early morning and evening when it cools down but once it hits about 10am and starts to warm up the panel it drops to 8v...
Does anyone have an ideas what might be causing this? Is the panel toast?
thx in advance

 

[mikefitz]

Is the panel toast?

Yes.
Thermal effects are causing intermittent connections within the array. Small panels are usually constructed with two sets of series connected cells, each set producing around 9 volts. They are connected in series with bypass diodes across each set, giving around 18 volts on load. If one set has a cell or interconnection fault, that set produces no power, but due to the bypass diode there is still some current flow from the good set, but the voltage at the panel terminals is half the nominal voltage.
Most flexible panels, (unless you pay for the top of the range) seem to fail within 2 years of installation.

Mike

 

[Traverse01]

Thanks mike, i was afraid of that and kinda thought that was the case..
mine was mounted about 15months.. rip

 

[sunshine]

i was afraid of that and kinda thought that was the case.

If you are stuck on Mars and need to get home, work out which of the rows is at fault then bridge that row with the diode from the good side.
You will need a sharp knife, wire, solder and tell us how it goes because I've never done a flexible panel only the standard type.

 

[Traverse01]

haha, yea i actually visually inspected each row and didn't see anything out of sort... I was thinking the same thing