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  • Sunking
    started a topic Electricity 4r Dummies & DIY

    Electricity 4r Dummies & DIY

    Here is a pictorial outlining DC Principles 101 every student learns in the 1st semester of school.


  • laser411
    replied
    Originally posted by bcroe View Post
    A diode won't conduct at very low applied forward voltage. A shorted load connected to the solar cell will take all the available current,
    but at zero volts takes no power. Increasing the load resistance slightly will generate some voltage drop and power transmitted to the
    load. More resistance will give more voltage and at first more power, but as the voltage increases the diode starts conducting. A
    point is reached where the power transmitted peaks; after that most of the current conducts internally and power delivered to the load
    drops off again, zero at open circuit. Bruce Roe
    Great explanation. I wasn't even thinking about the forward voltage drop, and when I did think about the forward voltage drop I was thinking "gee, there's no way a solar panel would be effective with a forward diode dropping everything but .7 Volts" forgetting for a moment that they are made out of like 60+ cells and that's a cell diagram not a panel diagram. Now I understand why the MPPT systems are necessary.

    Leave a comment:


  • laser411
    replied
    Originally posted by Sunking View Post
    Diodes only all current to flow in 1 direction also called a rectifier. Turns AC into DC. Think of them as a 1-way valve for current to flow in one direction only.
    Right, but in those diagrams, the diode is forward biased, pointing to the negative.

    Leave a comment:


  • Sunking
    replied
    Diodes only allow current to flow in 1 direction also called a rectifier. Turns AC into DC. Think of them as a 1-way valve for current to flow in one direction only.
    Last edited by Sunking; 07-31-2016, 08:27 PM.

    Leave a comment:


  • Mike90250
    replied
    Go to page http://www.pveducation.org/pvcdrom/s...ation/iv-curve

    Look and click through on the example as they start with the simple cell, add light etc. You were not looking at a cell and a diode, you were looking solely at the PV diode. IL is just a representation of adding light and generating current, not adding a diode to a solar cell. enjoy and don't jump ahead to lessons before you understand the earlier lessons. That appears to be a great teaching site, but you need some electricity and electronics background to grasp the info they have there.

    Leave a comment:


  • bcroe
    replied
    A diode won't conduct at very low applied forward voltage. A shorted load connected to the solar cell will take all the available current,
    but at zero volts takes no power. Increasing the load resistance slightly will generate some voltage drop and power transmitted to the
    load. More resistance will give more voltage and at first more power, but as the voltage increases the diode starts conducting. A
    point is reached where the power transmitted peaks; after that most of the current conducts internally and power delivered to the load
    drops off again, zero at open circuit. Bruce Roe

    Leave a comment:


  • laser411
    replied
    Oooh perfect person to ask my question to then. In an ideal solar cell diagram there is a diode that is pointed towards the negative terminal in parallel and the solar cell is thought as a constant current source. Why is that diode there? It would seem to me that the diode in that configuration would just shunt all of the energy straight to the negative and you would be unable to use it for a load?

    http://www.pveducation.org/pvcdrom/s...unt-resistance

    https://en.wikipedia.org/wiki/Theory_of_solar_cells
    ​See equivalent ​circuit of a solar cell
    Last edited by laser411; 07-27-2016, 11:28 AM. Reason: added link

    Leave a comment:

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