Connecting Multiple Solar Cells.

System
System Posts: 2,511 admin
Probaly a strange request, but I know very little about solar stuff & found this forum after a Google search. It seemed to be an appropriate place to post this question.

I'm about to install one of the small solar powered rechargeable LED's out in a pine plantation as a personal hobby project. The type I am talking about are the ones you buy in Wal-Mart for putting in your flower-bed, alongside your driveway, etc. They have a solar cell on top, one rechargable AA-size battery inside, & one small LED.

I have several of these lining my driveway & they work well, although I did replace the generic batteries which came with them, with a brand-name type. The generics just wouldn't power the LED but for 2 or 3 hours, even when fully charged. The more expensive ones will go all night long.

However, this one I'm putting out in the woods may have a problem getting direct sunlight to the cell very often, just when a sun-beam happens to penetrate the trees for a couple minutes, at just the right angle. I'm afraid what will happen is the light will only work for about an hour after sundown, then go off. I'd like it to burn at least till midnight or so.

So question is .... can I take an identical unit, pull the cell off of it, leaving wires intact, & simply wire it directly into the wires of the other cell which will stay on the unit? My intention is, if this will work, to take the additional cell & attach it up in a nearby tree, where it will get near-constant sunlight on it.

In effect, I will simply have 2 solar cells feeding the little recharge unit, rather than just the one that comes installed on it. BUT ... if the original cell also receives sunlight, will this result in supplying too MUCH power to the unit & possibly blowing the thing up? OR ... will wiring the 2nd cell directly into the wires of the original cell somehow let power feed back into either cell & damage them?

If so, I can simply pull the original cell off of the unit, attach long wires to it, & put it up in the tree, not even using the 2nd cell. But if my two-cell idea will work, I'd rather do it that way, as to leave the lighting unit fairly intact.

Thanks in advance.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Connecting Multiple Solar Cells.

    Hmmm... You could take small landscape LED fixtures and install a small panel remotely. The panel would most likely need to be either the same voltage/current as the original panel--or you would have to look at the unit and figure out the critical specification (say a set charging current) and set up the central panel to provide that required current...

    I would guess that the simple solar LED yard fixtures simply charge the battery without any regulation and light the LED until the battery goes dead. Because they use only one or two cells, the batteries can "safely" go dead without reverse charging (three or more batteries in series can damage the "pack" if one of the cells discharges first and the rest of the batteries "reverse" charge the weak cell).

    You can also find some LED landscape lighting that has a solar panel that can be moved into a location with better sun...

    But--I have a question--Do you need "reliable lighting" or are you more or less happy with the less expensive solar yard lights that probably last a year or so before needing work/replacement?

    In general, it seems that you will be lucky if the White LED's themselves last 1 year before losing much of their intensity (inexpensive While LED's are lucky to last a few thousand hours it seems).

    If you need lighting that is reliable and bright--Could you use a motion detector to only turn on the light when needed (brighter light on for short periods does not use that much power).

    There are Solar Charge Controllers made explicitly for landscape lighting (includes timer). Those could be setup to power a more permanent installation.

    Sunlight solar lighting controller 10-amp 12 volt

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset