Topic: Probable bad solar panel

[Skip_Amarillo]

I have an older VP.  It has worked well for several years.  A few weeks ago, I had a major computer crash, and had to replace my hard drive on my PC.  After my reload, I couldn't find my weatherlink install CD.  I managed to copy some saved files to get it working again.  I say all of that in case I screwed something up......LOL 

Shortly after all of that, I seem to be losing data after sunset, and into to the early morning hours, maybe like 9AM.  I got on the roof yesterday, and my voltage output from my solar panel is just over 1.1 volts.  The surface looks like it is 15 years old.......oh wait, it is.  As we know this is not available for replacement.

In an attempt to further trouble shoot the issue, I replace the battery with a none rechargeable just for test sake.  Seemed to work for a few minutes, but now I can keep a connection between my console and ISS. 

Any other ideas would be greatly appreciated.  I am NOT an engineer, but might have slightly above average skills........maybe sometimes.

[Skip_Amarillo]

I will try to post a picture.

[SLOweather]

Skip,

Please post more details regarding your testing. Was the panel disconnected ("open circuit") from the station when you measured the voltage?

What is the short circuit current in full sun?

What I see in your picture is a little crazing of the surface film of the panel. And your failure description (works in daylight, not at night) could support a diagnosis of a bad supercap.

[SLOweather]

Here are some observations on Davis panels. I should probably post as a sticky somewhere.

Like most photovoltaic panels, the cells are mounted on a rigid substrate (looks like PC board material to me).

Then they are encapsulated in a deformable (soft) clear rubber-like material. Over that is a clear harder film of some sort.

(Don't believe me? try gently pushing your thumbnail into the surface of a Davis panel. preferably in the narrow open are between cells. It's soft.)

This surface film is what crazes or gets cloudy. I have one panel in front of me that actually has a blister in the film.

So, unless the encapsulant s broken, cut, or otherwise compromised, the cells themselves should be fine. Like most panels the encapsulant will yellow a bit over time, reducing the output. I have some 40 year old panels from the first California Carrizo Plains PV plant that were yellowed when I got them from the mirror concentrators used back then. They still put out almost full power.

I have carefully buffed or polished the crazing out out or off a panel in the past. It might be worth spraying a light coat of polyurethane or clear lacquer on an old panel to see what happens.

[Aardvark]

The clouding sounds like the headlights of my aging Jeep.  The plastic tends to cloud over time and reduces the light. I am betting the same has happened with the Davis panel.  not that it gets (at least around my place) road salt and abrasion, but it does get weathering.  You convinced me, time for a new panel.   Scaled instruments here I come.

I could get the headlights polished and probably will one of these days.  I replaced them once, too expensive.

[Skip_Amarillo]

to SLOweather

I was in sunlight and disconnected from the board.  The sunlight was not as strong as we often have in the Texas Panhandle, but I expected more than 35% of the voltage I thought I should get.  I understand the Super Cap could have gone bad, but the new battery should have get me going for more than 15 minutes, right?  I am still getting reconnected, then I get error message on the status line saying  "R".  Trying to reacquire the signal, right.

[Skip_Amarillo]

I might try to polish the surface with a dremel brush. 

[Scalphunter]

Bon Ami or tooth paste like Sensodyne for polisher and wet rag.

John

[WheatonRon]

You say that you have an older VP. If a VP2, you can buy a replacement for about $50. If it is the original VP, I guess you need to contact Davis support to learn whether the panel on the VP2 is interchangable with the original VP.

[BigOkie]

Bon Ami or tooth paste like Sensodyne for polisher and wet rag.

John

Hmm..I use Sensodyne.  I might have to give that a try since my solar panels are starting to glaze over a little (3 years old VP2plus).

[Aardvark]

And my work is done here. The Colace is working and the Gym beckons.

I call the bathroom the "gym" then I can say honestly that I go to the gym several times a day.

[Garth Bock]

You said that you loose connection after sunset until mid morning ? Have you checked the supercapacitor ? I remember threads where a bad one even drained a replacement battery. The solar panel charges the supercap which the VP runs off of after dark. Even if the solar panel was cloudy if should provide from full sun enough of a charge on the supercap to allow the VP to run past dark at least. That is if the supercap is good. Sounds like the cap has gone bad. At least check it for leaks. It is not hard to replace.

[Aardvark]

Back from the gym.
The super cap is supposed to take the solar charge during the daytime and use it at night. The backup battery is used when there isn't enough charge. If you are replacing the battery often I definitely would unscrew the cover plate on the ISS board (don't drop the screws) and look at the super cap. It is a long cylinder and the corrosion is around the base of that. 

You have two options, one is to remove the board yourself and replace the super cap.  the other is to replace the board.   I am of the belief that these boards go bad more than not. Davis has a video on how to replace it.

The replacement unit is the back part of the ISS case, with a new antenna.  All you have to do is remove it according to the video https://www.youtube.com/watch?v=sCN3cuqaEEc

I buy all my parts from Scaled Instruments   https://www.scaledinstruments.com/      He sells the supercap and if you are handy with a solder iron or know someone who is, you can replace it yourself.   He also sells the unit  https://www.scaledinstruments.com/product/davis-7345-976-pcba-for-pro2-wireless-iss-or-iss-plus-us/

Let me throw in this.  Lets say you look at the supercap and it is fine,  it could be the charging circuit gone bad.  Then I would replace the board. Make sure you get the right version, either the US or the UK depending on where you live .   I had a soil moisture station that was eating back up batteries like candy.  I looked at the super cap and it was fine.  Contacted Davis and it was the charging circuit going bad.   I had them repair it.  Something to consider.

I like Scaled Instruments, he ships right away.  The solar panel  he sells for $24.00

[Skip_Amarillo]

Thanks Aardvark.  I have been trying to trouble shoot it from the roof of the garage.  It might be time to bring it down for a better look.  I didn't think the boards were still available sense the VP has been obsolete for some time no.  I thought it change when they went to the newer frequency.   I will pull the unit and look at the cap .  Not afraid to install a new one myself.  I was even thinking about running a three volts power to the connectors, and leave it plugged in all of the time.

[WheatonRon]

I have an older VP.  It has worked well for several years.  A few weeks ago, I had a major computer crash, and had to replace my hard drive on my PC.  After my reload, I couldn't find my weatherlink install CD.  I managed to copy some saved files to get it working again.  I say all of that in case I screwed something up......LOL 

Any other ideas would be greatly appreciated.  I am NOT an engineer, but might have slightly above average skills........maybe sometimes.

You do have a VP2 system and not the original VP, correct?

[Skip_Amarillo]

original VP

[Skip_Amarillo]

To Old Tele man .  Maybe 10ft.  And if I thought I was going to get too much voltage drop, I could cut that in half by running 110VAC just under my eve before I convert.

[WheatonRon]

original VP

Parts could be an issue--not sure of compatibility between the original and the VP2 but Davis support could tell you. Scaled Instruments sells VP2 parts, if not compatible, will have to buy elsewhere.

[WheatonRon]

I checked with Ryan at Scaled Instruments and he doesn't have the solar panel for the original VP and doesn't know anybody that sells it. Ryan also told me that most of the parts between the VP and the VP2 are not interchangeable.

[Aardvark]

The original unit is rare as hens teeth.   You might contact Davis to see if they have anything on a shelf somewhere, and on the other thought, would a vp2 solar panel work?

[WheatonRon]

The original unit is rare as hens teeth.   You might contact Davis to see if they have anything on a shelf somewhere, and on the other thought, would a vp2 solar panel work?

Good luck with your suggestion. Realistically, the person that raised this question should buy a VP2 or if money is an issue, find a used VP2. If Davis would release a VP3 that addresses my issues, then I would sell one of my VP2s for $100 plus shipping.

[WheatonRon]

Sounds like time for a little DIY-grafting of a VP2 external solar panel.

I think you are spot on.

[Skip_Amarillo]

Money is always an issue......LOL  But I think 100.00 would be pretty easy to come across.  It is the 750.00 that I get a bit chocked up on.  If I buy brand new, I would get a new weather link as well.  I bought this whole set up and never really got complete package that I would have plus support.

[WheatonRon]

Money is always an issue......LOL  But I think 100.00 would be pretty easy to come across.  It is the 750.00 that I get a bit chocked up on.  If I buy brand new, I would get a new weather link as well.  I bought this whole set up and never really got complete package that I would have plus support.

Scaled Instruments sells a new VP2 with Weatherlink, which includes the datalogger, for $545 plus shipping. A great price for a new setup.

[Garth Bock]

Part source for VP's is eBay....Just have to keep watching.

eBay item number:
201671608955

262618882392

232058751227