No, it does not.
I have always heard that a partially shaded panel will cut off. I accepted that.
We put our RV cover on this week. Some light does penetrate the material. It's "breathable". It passes less light than you would get parked under a fully leafed out oak tree. Isn't that a scientific measurement?
I was amazed that the panels are producing 1 amp. I suspect they would produce a little more, but the batteries are fully charged.
I can leave the temp controlled exhaust fan on so it can push some of the heat out and I don't have to leave the rig hooked up to shore power. One amp is twice what the fan uses, so no worries about discharging the batteries.
Right. Electrons out are proportional to photons in. In other words, as light falls off, output declines, but it's a slope--not like falling off a cliff.
(Or if you're a photographer, you can think of your panels as a giant light meter. ;-)
Andy, can you speak about the effect of having, perhaps, 4 panels or 2 panels, with one being partially shaded such as by the AC or the batwing antenna? Doesn't that dramatically reduce that one panel's output?
Thanks
Ken F in WY
For a typical panel with 36 cells, connected in series, completely shading one cell will cause it to appear open-circuit in the chain, completely eliminating output from the entire panel. Bypass diodes used in the panel typically allow most of the other cells to bypass the open, with a drop in panel voltage, which will allow charge to flow as long as the charge controller voltage exceeds the battery voltage. A partially shaded cell OR panel will allow reduced current to flow thru the entire panel. Newer panel designs appear to do better than older ones, and do well in low-light situation. However, a sharp, deep shadow across most of a panel can still kill any current from it.
Steve
"can you speak about the effect of having, perhaps, 4 panels or 2 panels, with one being partially shaded such as by the AC or the batwing antenna? Doesn't that dramatically reduce that one panel's output?"
Shading part of a panel decreases its output, but in my informal tests, the degradation seems to be gradual. I think it depends upon the kind of shade. If you place a piece of cardboard over one cell, completely blocking it, you may see the scenario Steve described: a major loss of power. On the other hand, the shadow of a tree branch is often blurred, and in my experience, causes less of a loss. And overcast skies (with even illumination across the panel) can still yield quite a bit of power.
With respect to multiple panels: it depends on how they are connected. If the panels are all connected in parallel, then even if one panel drops out completely due to a shadow, you'll still have all the other panels producing full power. On the other hand, if all the panels are connected in series, you'd see a major drop in power in that scenario.
In practice, series-parallel pairs have proven to be a good compromise. As I and others have said elsewhere, this configuration gives you the benefits of higher voltage (more efficient MPPT controller operation, less voltage drop, etc.) while minimizing the chances of a shadow bringing down your whole array. Traditionally, RV solar panels have been wired in parallel--that's how I wired Gertie--but with MPPT controllers becoming standard, series-parallel hookups are becoming more and more common.