Modifying old Panels

[Kappy]

As many are aware my bus is now running on a 400aH 12 volt LiFePo4 system and I'm well pleased and grateful to T1 terry for his expertise.

I discussed with Terry about utilizing my old 24 volt panels on my trailer and using whats left of the life of my 3 X 100ah 12 volt AGM to run a 12 volt system on my trailer. Mainly for internal lights ,tailgate winch and brakeaway brakes.

He suggested converting each 24 v panel into 2 x 12v panel and described how to go about it.

Because my memory isn't that flash and either I lack the courage to potentially ruin a panel I seek advise here.

Ive searched high and low for a YouTube on how to do the surgery, so can anyone maybe guide me to a video or pics of it being done.

Or do I just rune as 24v and use the converter for 12v and only use 2 AGMs for 100aH.

Cheers

[native pepper]

If you are using an mppt controller you can use them as 24v panels, if you already are using 12v panels, then there must be a way to set them up properly and Terry would know how to do that. I certainly don't. I've got 12v panels on one system at home and 24v panels on another, as well as the bus on mppt controllers. My 12v setup tuns on a pwm controller, which had built in India and was supposed to be mppt, but soon worked out it wasn't and would never get anything from India again.

[jon_d]

Kappy,

Maybe have a look at one of these;

https://www.mppsolar.com/v3/pcm20123012-series/

The work well with 24 volt panels and convert down to 12V batteries.

[Kappy]

If you are using an mppt controller you can use them as 24v panels, if you already are using 12v panels, then there must be a way to set them up properly and Terry would know how to do that. I certainly don't. I've got 12v panels on one system at home and 24v panels on another, as well as the bus on mppt controllers. My 12v setup tuns on a pwm controller, which had built in India and was supposed to be mppt, but soon worked out it wasn't and would never get anything from India again.

Using existing Steca Controller.

I have 3 x 200 watt 24 volt panels

[BruceS]

This might help you?
http://www.instructables.com/id/How-to- ... olar-Cell/
Take notice of the diodes!
First thing to do is to see what it looks like in that little box on the back of the panels & then get busy with the multimeter set on 100V.
Make sure it's not set on 20V or less.

[jon_d]

Kappy, what model stecca?

[Kappy]

Kappy, what model stecca?

PR 3030

[T1 Terry]

I've had a search through my 'puter and I can't find the photos from my last panel mod, if I get a day free I'll do another one and document it in a folder I can find again.
The basics of the process:
1) looking from the glass side at the opposite end of the panel to where the black connection box is fixed, you will see a silver tape section that joins the left hand grid section to the right hand grid section.
2) Turn the panel over so you are looking at the white plastic sheet side, shine a bright torch from the glass side where the silver tape joins the 2 sides. Use a marker pen to draw out where the tape shows as a dark section under the white plastic layer.
3) Using a burring tool in a drill or one of those Dremel type tools, carefully remove the white plastic where the silver tape was marked out roughly centre from side to side with enough exposed to solder wires to the silver tape.
4) Now carefully cut the silver tape with a Stanley knife and roll the ends back over the silver tape so there is a gap between each end of the silver tape
5) Using a hot soldering iron build a solder tab on each of the rolled back sections of the silver tape.
6) Look inside the black terminal box to see which cable is positive and which cable is negative. If it isn't marked, put one lead from a multimeter on the cable and the other lead on the new solder tab you just made. It should read around 20v with the panel in the sun, look for a (-) sign beside the voltage reading, if there is a (-) sign swap the multimeter leads over between the solder tab and the original cable coming from the terminal box.
7) The red multimeter lead is the + end on the new 12v panel and the black multimeter lead is the negative. Mark the solder tab and cable accordingly and move on to the other half of the panel, it should be the opposite way around, one solder tab is positive and the other negative.
8) Using 6mm auto cable, solder the red wire to the + solder tab and the black cable to the (-) solder tab and roll out enough cable to reach the black plastic terminal box on the other end of the panel or even enough to reach the ends of the original cables.
9) Now seal the ends where the wires were soldered on with some of the Selleys Armourflex or Soudal T Rex sealant to keep any moisture out. Do not use silicon for this job as a lot of it is acid cure and it will eat the silver tape away.

You now have 2 x 12v panels, if it was originally a 200w panel @ 24v you now have 2 x 100w panels @ 12v, one of the original cables and the new cable from that side makes one 12v panel and the same on the other side makes the second panel.

I bet the eyes are rolling now but as you do each step re-read the next step and it will all fall into place

[Kappy]

Thanks Terry

I had a play today.

Located the silver strip to modify.

20170830_163901.jpg

Once confident where to start, I modified the frame to allow better access.

I removed the backing plastic with a soldering iron and cut the silver strip and started testing

A standard 24v panel was showing 44.4V

I started getting some interesting readings between the original + & - and the new + & -.

I thought more research needed.

The new reading between the old + and new - was about 6 volts, nothing looked right.

Reading between old + and - was around 26 V.

Time for a cuppa.

Retested and this time , reading between old Pos and new Neg was about 19.5 Volt same for Old Neg and New Pos.

More pics in album as I could only 1 172 KB photo other smaller pics wouldn't up load.

More to come

Cheers

Kappy

[jon_d]

Well Done Kappy.

Just remember to seal it up water tight; as you don't want water ingress over time.

(And stress relief the wires so the don't break the silver strips.)