Let's Make Robots!

Multiple power supplies, one way.

First off, I'm using a Pixaxe board.

Considering the juice that can be used by periphrials, I wanted to use it's ability to use multiple power supplies,
one for the board, and one for the "output devices". However, a small question, just to be sure:
 A SHARP sensor is NOT consiered an "output device" on the board, right? I think it's not, but making sure...

Anyhow, I wanted to run the motors up to their maximum 5v-6v capacity.
I was thinking of using 2 power sources, including a small solar pannel, on a parallel circuit to the battery,
then finally to the power pins on the board.

Now, my question is here, since I know little about solar panels:
Should I have something like a transister between the solar panel and the batteries in the parallel circuit,
so that  the voltage from the batteries don't wash back into the solar panel?

I want the power from the solar panel to travel through the battery,
then the battery and/or the solar panel to connect to the power pin,
BUT I do not want the power from the battery to go to the solar panel:
When it's dark, voltage would NORMALLY go there,
considering that it's not generating, but still on the circuit.

What would you recommend to only allow OUTGOING voltage to pass; OR
only allow the voltage to/from the solar panel IF it's generating power?

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Edited out, wrong thread >_<
(Can't find the delete button) 

Thanks for the response.

But I wasn't asking how much power a SHARP takes, but rather if it's connecting to the same power source as the servos.

On the second note, I'm not worried about frying the solar panel, as to charge the battery would have to be a LOWER voltage, for it to even get charged by the solar panel. My concern, is because of how electricity works, I don't want to lose battery life by the batteries trying to travel into the solar panel, when it's not generating anything.

I know a lower voltage shouldn't blow it out, I just don't want to drain the batteries fast, the reason I'm using solar panels in the first place. So, when I get the parts, I'm going to try to put the recommended diode in there,
so the batteries only go where they need to: The servos. 

Sharp sensors are not output-they do take a little current but not on the level of a motor/servo. What you're describing otherwise is a diode to keep current from flowing the wrong way, but I wouldn't think it would be a big issue in the setup you're using. I don't think you have to worry about frying the solar panel. Just make sure you do your math so you don't start a battery fire or inadvertently drain the battery rather than trickle charge it.