Original Solar Panels

[HereComesTrouble]

Does anyone have an original data sheet on the original 50 or 55 watt panels that came on these vehicles. I'm just wondering what the specs are and if that panel could be used in some way with a set of Renogy Eclipse 100 watt panels. In my case, the original sits in the center of the cab roof. If it could be used, in conjunction with the new panels, I could get a slight bonus of a couple more watts. Has anyone tried leaving the original connected with their upgrade? Enquiring minds would like to know. TIA for any responses.

[Blue~Go]

I have the specs and will add them below.

I wouldn't use the original panel along with any "modern" panels. Reason being that the voltage on the original Siemens panel is rather low, at 15.9 volts (Vmp). It's good to have the voltages of panels either exactly matching, or within .5 volts. Otherwise the concern is that all the panels are dragged down to the lower voltage. Most modern "12 volt" panels are at least 17.5 and sometimes as high as 19 volts (Vmp).

Hooking up two of the original panels would work (they aren't made anymore but some Chinookers may have one available). You could put them in series to get the voltage up a bit. Of course that's still onlly 100 watts.

15.9 volts is not really desirable because you need like 14.4 volts (or even up to 15 volts in cold weather) just to charge the batteries in the absorb stage (presuming lead-acid batteries for now as not many are using lithium yet) and having the panel voltage too close to the desired voltage doesn't give much "head" to work with. Not that the panels can't work, especially if you can get two or four of them; but just saying why if I were putting on new/larger panels I would not (and didn't) include the original Siemens panel in the mix.

I saved mine though. Could come in handy for some stand-alone purpose. IIRC someone used their take-off for lighting a small garden shed.

Here are the specs for the panel that was on my rig:

Siemens panel spec sm50-h.pdf

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By the way, when/if you do remove the panel, the specs will usually be on the underside. In case yours is different than the above.

[HereComesTrouble]

Oh well I was hoping, I could avoid the panels overhanging my roof, as my luck has not been the best with tree branches. We sold our class C because of a piece of a Sequoia that fell and decided to eat the corner of our overhead sleeping compartment. As always, thanks for being so generous with both, your time and your advice.

[Blue~Go]

Well, if you think 140 (or possibly 210) watts will be adequate, then you could go with the Solarland SLP070-12M. They are ~13" wide x ~58" long and each panel is 70 watts. They are a slightly older panel design, by which I mean that now you can get more "watts per area," and watts-per-dollar; but that may not matter to you if what you want is panels that don't overhang, and if the wattage is enough. I thought very seriously about them, but since I already have two panels of ~21" x ~58" that are 135 watts each, I couldn't quite go for the SLP's.

Here is the data sheet on them. They are polycrystalline panels. They typically run about $225-$250 apiece.

SLP070-12M.pdf

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