# COMMUNITY : FORUMS : BURNING QUESTIONS

## solar outlet

would anyone know how to create a solar outlet? I have seen many projects that use small solar panels and car chargers or USB ports, but some electronics that might need charging or power  dont have car chargers or USBs. Is it possible to make a portable solar outlet?

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kelseymh7 years ago
What do you mean by "outlet"?  You mean a mains-like two-prong or three-prong wall outlet?  Since PV cells output DC, you would need an inverter to convert the DC to AC, and you wouldn't get much current out for charging.  Now picture carrying around a rooftop's worth of 4'x8' solar panels :-)
lethereberock009 (author)  kelseymh7 years ago
yes, a wall outlet. would you be able to get enough energy to power a cell phone or other small gadget?
7 years ago
Well, let's do the math.  Suppose you want to charge something equivalent to what a USB charger can do, 5 volts at 500 mA (0.5 A) (i.e., 2.5 watts).  We know you can build a portable solar charger with that output.

What would happen if you put that current and voltage through an inverter to get something that looked like mains?  Ignoring any resistive losses, you're converting 5 VDC to 117 VAC (rms), so your 500 mA input drops to 21 mA output.  I'm not sure you're going to do much of anything with 21 mA (max) coming out of a "wall plug."

For any small gadget that uses an AC-to-DC adapter, even one with some weird custom plug, you would be much better off simply taking that adapter, cutting off the big back box, and wiring the cut wire ends to a solar cell.
lethereberock009 (author)  kelseymh7 years ago
and connecting directly from the solar panel to the device wouldnt hurt it any? if the sun wasnt on the solar panel would the power from the device go back to the solar panel?
7 years ago
No.  A photovoltaic cell is basically a diode.  Think of it as an LED in reverse -- light comes in, and current goes out.  Like any diode, it only allows current to flow one way.

If you do "reverse bias" it, it acts like an open circuit (unless you exceed the breakdown voltage :-).

Try a bit of Web research on "diode" and "photovoltaic," or pick up a simple electronics book.
Big Ugly Mich7 years ago
You can hook up a 12 VDC outlet to a solar panel, but don't expect to get a ton of current off it, and your panel better make 12 volts, otherwise it's a waste of time and stuff.