# 24V Solar panels, use on 12V?

2 Posts
Apr 26, 2006 04:40 am
24V Solar panels, use on 12V?

I wired up a group of older solar panels in 24V configuration.  This is at a remote location in Bahamas.  Homeowner needs to send 24V inverter for repair, has spare 12V inverter.  It is easy to rewire batteries for 12V, but solar panel wiring is not easy.  As a temporary measure, can the panels connected for 24V just be connected to the 12V batteries?  There is no regulator and the output of the panels will not overcharge the batteries, as generator needs to still be run to keep up with needs.

1 Posts
Apr 26, 2006 09:29 pm
I NED A QUOTE

HOW MUCH A PANEL PHOTOVOLTAIC

Apr 29, 2006 10:42 pm
Re: 24V Solar panels, use on 12V?

It would depend on how the batteries are configured. If there are 4- 6 volt or 2- 12 volt batteries in series you could tap into the bank half way and get 12 volts (be sure all wire sizes are correct for the amperages being conducted through them). This way the batteries can stay 24 volts nominal being recharged by the 24 volt PV array. If left like this for long though it could shorten the longevity of those 2 batteries faster than the other two, so if it is to be left like this for a long time it would be wise to move the leads for the inverter back and forth occasionally.

2 Posts
May 1, 2006 06:57 am

I guess the question is, will I damage the panels?
Can solar panels be left shorted and in sun without damage?  If so, then if they were connected in series for 24V but used on 12V, there would be no damage to the panels. I am just not familiar with the durability of the panels.

May 12, 2006 06:15 am

If I were in your shoes, what I might do is; to leave the PV array at 24 volts nominal, leave the battery bank at 24 volts nominal, then tap into the battery bank "halfway" to get 12 volts nominal for the 12 volt nominal inverter. Do you or do you not have batteries wired in series? What is the nominal voltage of each one of the batteries? 2, 4, 6, 8, 12, 24?
At the very least you either have;
1 - 24 volt battery by its self or,
12 - 2 volt batteries in series or,
6 - 4 volt batteries in series or,
4 - 6 volt batteries in series or,
3 - 8 volt batteries in series or,
2 - 12 volt batteries.
If its any but the first in this list or 3 - 8's you can tap into them "halfway" and get 12 volts nominal.
Take your multimeter and hold the black lead at the negative end of the battery bank, then take the red lead and move from battery terminal to battery terminal until your meter reads 12 volts.
Now do you get it?
Think about it this way: if I had 2 - 12 volt batteries wired in series I would have a wire from the positive lead of one to the negative lead of the other. Now when I measure the voltage at the other pos. and neg. terminals I have 24 volts, BUT!!! if I measure the pos. and neg. on just one of those batteries I still can get 12 volts. This works weather its; 12 -2's, 2 - 12's, 6 - 4's, or 4 -6's but not if its 1 -24, or 3 - 8's.
Its all in the math.

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