[David Wallace]

Can anyone help to identify the two solar panels I have on the roof of our caravan. The first solar panel came with the caravan from new and the second panel has been installed latter by the previous owner who told me they where 150w each. The first panel I'm pretty shore is a Polycrystalline? and is 1480mm x 675mm and is 9 x 4 cells and is 150watts.

Panel No1 Poly 9x 4

The second panel I'm not to shore about. I think its a monocystalline? and is 1325mm x 680mm and has 8 x 4 cells. It may only be 120w as I have looked on line and it can be confusing when some panels have as mush cells as the 150w panel but are only rated at 100W!

Panel No2 Mono 8 x 4

And why do manufactures put the panel spec. on the underside where they cannot been seen I wont be removing the panels to find out that info

[Andycap]

Hi ,on a past m/h i had i needed the same info ,Taped my phone to a flat bit of lathe,in camera mode, slid under and tapped the button with another thin stick .Addmitadly the label was fairly close to the edge.

[scubadoo]

We would all be guessing with size measurement versus wattage output. I would expect them to be similar. 300W is probably near enough.
Maximum observed current into your battery would be a good indicator.

There are several methods to estimate the output of each panel but some would require a little effort and may not be worthwhile.


PS Good thinking Andycap.
Reminds me of my very early method for reading battery cell voltages. Cheap phone as webcam viewing the meter in the battery well to another phone for observation.

[Neddy]

Panel 1 is a "12 Volt" Polycrystalline solar panel, almost certainly 150 Watts.

Panel 2 is a "12 Volt" Monocrystalline solar panel, again, almost certainly 150 Watts.

[David Wallace]

Thanks for every ones help. I tried the cell phone method but panel two is too close too the roof to fit anything under and the phone is too close to underside of panel two to see any thing. Im going to assume they are 150w each as your posts suggest and the previous owner indicated. Next time the panels are out in the sun I do some volt and amp measurements. I just got one of these in the mail the other day. Another fun job to add to the caravan improvement list.

Power meter for my lifepo4 battery monitoring.