Off Grid Living / Camping > Off Grid Living / Alternative Housing
12v or 24 v solar
gww:
There might be one other option depending on the voltage of the 24 watt panel and the batteries you use. If the 24 volt panel had a voltage of 28.6 or something, you might be able to hook it strait to the battery with no charge controller and it would probly be in the voltage range where it wouldn't hurt some batteries. If you faced it a bit east you would lose some production but it would still be a big help in bulking the batterys. This is only if you ended up with a 24 volt battery bank which you probly don't need. Are you wanting to add loads that you don't run now?
gww
rclark:
As others have said, there may not necessarily be harm from doing it otherwise, but it's generally best to match your panels to your voltage. Frankly, in my experience I've found that putting in the extra leg work (or money) to make it right the first time pays off in the long term because I have less maintenance issues and other hassles to worry about.
MadScientist267:
--- Quote from: A of J on January 16, 2015, 03:30:36 pm ---Solar panels are DC beasts and as such it is voltage that takes precedent.
--- End quote ---
I realize this really isn't an active thread now, but I was reading back thru some of the older stuff under leisure and saw this...
A of J, you're correct with this provided the context you used later in the post is present.
However - PV is a current source, not a voltage source. A single solar cell is really nothing more than an oversize diode that is optimized to catch light. The current that any given cell passes is proportional to the amount of light caught.
I wanted to clarify for future readers of this thread that if a single cell of any given size is placed in series with a larger cell, and exposed to equal quality and quantity of incident light, the current will be limited to the Isc rating of the smaller cell, absolute best case.
You can also think of this another way: Take two identical cells and place them in series, equal quality/quantity light, just as above, and partially shade one of the cells. The current that will pass thru the shaded cell will roughly approximate that of a completely exposed cell the same size as the unshaded area. This of course then scales right up, as the typical panel is a single string of identical cells (not always, but that's another story and really has no bearing as far as this goes).
One other related point... Being a "diode", a cell is also subject to similar rules as their tiny counterparts... The primary difference is that light causes forward conduction. Shaded or "missing", doesn't matter, because the shaded area is effectively reverse biased, and therefore "open". This is why shading only a single cell in a panel will render it "powerless" (bypass diodes are used to address this issue).
I apologize if I took this way out on a tangent, but I think the thread demanded it for completeness... and maybe I'm a little bored LOL
Steve
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