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Homework Help: Solar Cell calculating the power output

  1. Apr 28, 2008 #1
    1. The problem statement, all variables and given/known data
    I am asked to plan a practical to determine the power output of a solar cell, i.e how much light energy is converted toe electrical energy per second. Now I thought(obviously) to just connect voltmeter accross it with an ammeter and use PVI, however thinking about it, I don't know if this would work. It might just be my circuit theory but there is nowhere for the energy to go out of the circuit and so won't it just build up so that you have all the electrical energy it has produced as well as what it is producing now. I had another method for it, however, from the mark allocation I think it is too complicated especially as at first this seems like a really easy solution. My more complicated method, was to store all the energy for say a one sec burst of light, on a capacitor and then to discharge it through a resistor with a voltmeter across it, then using V= Vo*e^(-t/RC) to calculate initial voltage accross the capacitor and ten use E= o.5CV^2 Can someone just explain why the first method is wrong/right cos its proper fuzzled my way fo thinking of things, btw i'm jst finishing a-level physics to go do it at uni, so i understand most things, but this jst got me thinking

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 28, 2008 #2
    use a variable resistance/and measure the current and voltage for a range of load resistances at a constant light intensity. If you short the cell you get maximum current and no power, and if you have an open circuit you get maximum voltage and also no power. The maximum power delivered to the load should be somewhere between that.

    Your capacitor idea is problematic because the voltage and current won't be constant when charging it.
  4. Apr 29, 2008 #3
    thanks, very much,
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