Quote:
Originally Posted by scrubjaysnest
With shading panel output drops by 90% that is why we use 2 - 100 watt portables until we get home this winter. Parallel wired panels will do better then series wired so you loose the advantage of higher input voltage for the MPPT.
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Portable panels do offer many very useful temptations, but with age I find my end-of-day priorities much different than I once did … younger folks say I've become lazy … I think I've heard something like that from folks setting up camp while I'm comfortably lounged, sipping a perfectly mixed margarita. I throw that last comment in humor, not personal … if you are older, you know … if not, you will. A
throw it on the roof and forget it mentality is more appealing to me. But yet, I try to keep open to better ideas: What kind of portable panels are you using? And, where in your Sprinter do you store them?
An added point: A shadow does not necessarily reduce output by 90%. A partial shading of a single panel reduces its output somewhat; a gray sky also reduces panel output, a dark sky reduces it more, and the shadow of a cloudy dark night might even reduce it 100%. Dust on the panel is a shadow. A little dust might reduce efficiency 10-20%, while an 1/8th inch of dust would reduce it 100%. Manufacturers assemble individual panels with an array of photo-voltaic cells, usually several series-wired cells connected in parallel. These panels can be connected together to create larger similar arrays. Most commercially available panels are configured to produce about 17 volts. Such panel is well suited for 12 volt battery charging because it is convenient to manage the output potential of 17 volt arrays to various 12.x volt charging systems. In such system, these panels would best be wired in parallel. A 24 volt charge system might be conveniently assembled by wiring two series configured panels in parallel with other series-wired panels. Such would produce a 34 volt array which is convenient for managing 24 volt charging systems.
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