Solar Panel question: Short or Open?

Discussion in 'General Technical Questions and Answers' started by WA7ARK, May 12, 2020.

ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: Left-3
ad: abrind-2
ad: Left-2
ad: Subscribe
  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    Say you have a 250W (~36V open circuit voltage) solar panel. Assuming the panel is in direct sun when you are not using its output, is it better to open-circuit the panel , or is it better to short-circuit it?
     
  2. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    If short circuited there will be more waste heat which might reduce long term reliability, compared to storing it open circuit, but otherwise it shouldn't matter. A PV cell is basically current source anyway. Open circuit certainly isn't going to hurt the panel, in normal operation a controller will essentially do that if power isn't needed.

    Disclaimer: I have no direct experience just going by basic principles here.
     
  3. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hi Mike:

    I strongly suggest NOT shorting out your solar panels, especially if they are out in bright sunlight. Less heat generation and lower current stress is always better. The PN junctions of the two bypass diodes normally found in each panel heat significantly when current passes through them, and at your QTH the sun can be intense and temperatures already high. MIL-HDBK-217 recommendations follow this philosophy and there are established time/temperature/life curves for diodes. Lower temperature, lower current, longer life. Plus, if there IS a failure, why have a closed circuit ready and waiting for that failure to take advantage of?

    I have a rotating 4 x 100W (Grade A) panel system pole mounted in my back yard. On an average day it will easily generate about 320+ watts after the MPPT controller. Power from the panel is lead into the house at about 90 volts open circuit.

    I leave the circuit OPEN when not in use and this works fine. But I do cap off the leads if not in use for a while - very easy to do. This arrangement has worked fine for about five years now.

    Stay Safe!

    Brian - K6BRN
     

Share This Page