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Measuring solar panel voltage. — Parallax Forums

Measuring solar panel voltage.

bubby9534bubby9534 Posts: 36
edited 2012-09-28 00:31 in BASIC Stamp
I know this is a vague question, but I have no idea where to start.

I have a solar panel and I've hooked it up to an LED on the solderless breadboard on the BOE Board, but now I'd like to use the BS2 chip to measure the voltage of the solar panel. I know that I might use RCTime, a capacitor, and maybe a trasistor? I'm really lost and would like help if your willing to spare the time.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2012-07-14 21:11
    Look at EmeSystems's website. Use the "app-notes" link and look at the discussion on measuring battery voltage using RCTIME.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2012-07-14 21:50
    As Mike said, follow the link and see how to use RCtime.

    May I ask how big the panels are and what kind of a load you are placing on them? Reason I say this is because solar panels should be measured in two different ways to determine the maximum amount of power that they can deliver. First with an open circuit, and then with a known or dynamic load applied to them. With larger panels and requirements this becomes more important. With smaller applications it's not as critical.
  • bubby9534bubby9534 Posts: 36
    edited 2012-07-16 10:23
    I have a really small solar panel (6V, 85 mA, 0.5 W) about the size of an iPhone. Also, is the 681 kohm resistor really necessary, is there an alternative, or will I have to order that part. Thanks!

    Edit: I tested with out the resistor it worked great, thank you! There was a very small maximum voltage however, so I'll get that resistor soon. Thanks!
  • bubby9534bubby9534 Posts: 36
    edited 2012-07-16 13:24
    How do I set the status to solved?
  • FranklinFranklin Posts: 4,747
    edited 2012-07-16 13:40
    I don't know how you have the panel connected but you don't want to put 6v on a stamp pin nor more than 20ma.
  • bubby9534bubby9534 Posts: 36
    edited 2012-07-16 13:59
    Franklin wrote: »
    I don't know how you have the panel connected but you don't want to put 6v on a stamp pin nor more than 20ma.
    Right, wouldn't the transistor prevent that? because I have the + wire from the panel on the transistor base and the pin on the emitter and the capacitor on the collector
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2012-07-16 14:09
    bubby9534 wrote: »
    How do I set the status to solved?

    I took care of that for you, but in the future you would do it by editing your message and selecting Advanced Mode. Take care.
  • andrew_paul111andrew_paul111 Posts: 1
    edited 2012-09-28 00:31
    The power generated by any solar panel in full sunlight depends on the resistance of the electrical load connected to it. Resistance is measured in units of Ohms. The relationship between current, voltage and resistance is referred to as Ohm's law. The current through a resistor is the applied voltage divided by the resistance.The power output of a solar panel depends on the resistance of the electrical load to which it is connected. In an open circuit situation (infinite resistance) the voltage of the solar panel will be high, but no current will flow and therefore no power is generated.



    solar energy system
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