PV Gap

Lynn Said:

How many Solar cells are required?

We Answered:

About 450 watt-hours - that sounds like an electric bike battery. Is it 36 volts?

What you need is to find a 200-watt panel with a max power voltage of 42 volts or more, or two, 100-watt panels in series. 100-watt panels are not the mainstream, anymore, so you may have to go with 165-watt.

You would also need a charge controller for the battery pack. I've seen some electric bikes here with a switching power supply for their charger. For those, I believe you could wire the charger directly to high voltage DC, and it would work. But you would need to supply the mains voltage times 1.4 to the charger. That means 150 volts at least in my area, which implies 6 panels. Expensive, unless you already have such an array for other purposes.

Sorry, I don't have a source for individual cells. They are sold on craigslist where I live. But my personal opinion is that building your own panel is a poor value - it costs almost as much, and won't last very long.

Zachary Said:

To build solar charger for 6 AA how do i make a regulator that will deal with varying input V &no overcharge?

We Answered:

Solar chargers tend to be slow. If you really want to use your batteries a lot, I'd suggest buying a charger that plugs into the wall and does 4 AA batteries at a time. Those can be found for $10, maybe even less. You could even get two of them.

If you must use solar, then I'd suggest getting as many more solar chargers as you need to do 6 batteries at a time.

Wesley Said:

how to build a mini robot that has solar cells?

We Answered:

The solar cells are just your power source. You need to apply that power source (voltage) to your robot's motors.
Diodes would just prevent current flow in the opposite direction, not sure what you're looking to use them for.
Capacitors could be useful if put in parallel with your solar circuit, since they could supplement current loss from the solar cells when your robot goes through a shadow or something.