# Solar panel

Discussion in 'Electronic Basics' started by Vince, Oct 2, 2005.

1. ### VinceGuest

Hi,

I have a solar panel which generates a max of 2W out.

Would it be possible to trickle chargle batteries of a higher voltage?

I have a high voltage battery (12VDC...ok not that high) running many
smaller low voltage LED's. As the LED's dont use much energy, Im assuming
that a small solar panel can put back what the LED's took out.

If this is possible, do I need any extra's to hook it up besides a diode?
Also, does voltage or current play a role in my answer?

2. ### Rheilly PhoullGuest

Yes Vincent
The voltage output is very important and your question cannot be answered
without clairvoyance ;_)
You will have to find out the voltage (output by the panel) by measurement
or a nameplate etc.
To charge the 12v battery it would want to be at least 14v output.

3. ### outer_spaceGuest

That violates the conservation of energy principle, you can't run LEDs
off a battery and recharge that battery with a solar panel powered by
the LEDs. LEDs are at most 40% efficient at converting power to light,
solar panels are %20 (not sure) and you lose even more power in the
battery. An LED array takes a lot of power more than just several
watts.

4. ### BobGGuest

Would it be possible to trickle chargle batteries of a higher voltage?
====================================================
There are very efficient (80 to 90%!) dc to dc converters that accept
input volts over a 4:1 range 9 to 36 volts. A 12V solar panel is
typically 21V and 0 ma or 0V at 320ma or somewhere in between like
12v and 160ma. or 14V and 130ma (about 2 watts). Check out electronics
places like Jameco, Digikey to look for dc to dc converters and power
supplies.

5. ### ehsjrGuest

Yes. A boost converter can increase the voltage. What voltage does

It depends on how much current the LEDs use. "Many" LEDs could mean
5 or 500 or ?? If the LEDs take out less than 2 watts and the panel
produces 2 watts then (ignoring losses) your panel can put back in
what the LEDs took out.
Yes and yes. You'll need a DC-DC converter to raise the voltage
to the voltage needed for trickle charge - and you need to know
how much current the LEDs use to decide whether the project is
worthwhile.

Ed

6. ### BobGGuest

Nobody metioned power yet. Red blue and green leds have diff
voltages... but .02amps and 3v will run one...thats .06watts, so a
2watt panel will run 33 leds.