Hi gang,

Well, after 2 years with 30 PhotoWatt PW1000 (100Watt) Panels, I'm noticing that the backside electrical connections are coming loose. Symptom is low power output, caused by loose connections.

On the back of each panel is a weatherproof plastic box. Within the box is a 7-screw electrical junction strip, used to jumper the panel for 12V/24V operation, and for external electrical connections. The terminal strip uses 6x32 screws to clamp wires or solderless terminals.

When I put the panels up 2 years ago, I torqued all the wires to 12 in-lbs.

Now (August 2003), I find that many of the screws have loosened, resulting in high-resistance connections (sometimes open circuits!). In one case, I could see pitting caused by sparks on the barrier-strip.

Probable culprit? Repeated hot-cold cycles. From day to night, the barrier strips vary over 100 degrees F. Bit by bit, the thermal expansion/contraction forces the screw to slowly untwist.

Looks like every year I should climb my roof, unmount each panel, and re-tighten each screw. My installation has some 200+ such screws.

I'll probably retrofit with lockwashers and perhaps anerobic loctite threadlock. I wonder if there's an electrically conductive loctite?

-Cliff

I wonder if the problem is screw turning or deforming of the wires.

When I installed my SP75s using #10 stranded wire, I found that the screws needed retightening on 3 different days. This did not make me very comfortable.

Gordon

Hey guys!

In the trades, that type of problem is dealt with by using lock washers or spring washers (both available in brass coated or stainless), and giving serious consideration to the use of a locktite thread adhesive!

DJ

On my First array , I used solder terminals , never had a problem. On my current array , I used #10 stranded , right to the terminal strip and just last week I had a string "fail" ... loose wire ... I'm having similar doubts about not using lugs !

I also had loose connection problems on my first 24 KC120 panels. I used #10 wire with spade connectors - I replaced these with ring connections and haven't had any additional problems.

I think the spade coneectors failed due to the reduced surface area at the connection - ring connectors provide a lot more surface area!

I now have 56 KC120 panels connected with ring connectors for over one year with no failures. In Livermore, CA - I can see daily temperature swings of over 60 degrees F. during the summer months

My 16 KC125 panels with MC connectors are really the way to go!