Groups > sci.electronics.design > #519034

Re: Can a small photocell panel be connected to a flashlight type rechargable battery?

From	John S <Sophi.2@invalid.org>
Newsgroups	sci.electronics.design
Subject	Re: Can a small photocell panel be connected to a flashlight type rechargable battery?
Date	2018-10-12 02:12 -0500
Organization	A noiseless patient Spider
Message-ID	<ppphfo$tot$1@dont-email.me> (permalink)
References	<fhntrd1aq3c9jkfp3haigrk512mdfc5aj8@4ax.com> <986vrddm75p51iimfob41mb9gvhpga930r@4ax.com> <ppoj5t$3ph$1@gonzo.alcatraz> <0k00sdt1dmep23fc5f6gcdnu6m89bjl52h@4ax.com>

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On 10/11/2018 9:31 PM, Jeff Liebermann wrote:
> On Thu, 11 Oct 2018 22:34:37 -0000 (UTC), Jasen Betts
> <jasen@xnet.co.nz> wrote:
> 
>> On 2018-10-11, Jeff Liebermann <jeffl@cruzio.com> wrote:
>>
>>> Well, try it.  You should measure the open circuit voltage and the
>>> short circuit current.  Don't leave the ammeter across the panel for
>>> very long or the panel might overheat.
> 
>> They don't change colour in response to a load, open-circuit and short
>> circuit produce almost exactly the same self-heating
> 
> Change color?  No, I didn't say that.
> 
> I use a short circuit test to check for defective cells in a panel.
> Short the panel, full sunlight, and use an IR camera or IR thermometer
> to measure the temperature rise of each cell.  A defective cell will
> usually be warmer than the other normal cells:
> <https://www.novuslight.com/testing-solar-panels-with-thermal-imaging-cameras_N7799.html>
> <https://solarprofessional.com/sites/default/files/articles/images/10_NEW_SP7_2_pg24_Mehalic-7.jpg>
> "Hotspots Detection in Photovoltaic Modules Using Infrared
> Thermography"
> <https://www.matec-conferences.org/articles/matecconf/pdf/2016/33/matecconf_icmit2016_10015.pdf>
> For example, when someone shorts a 300 watt panel, that generated
> power has to be dissipated somewhere, which means dissipated in the
> solar cells.  With 60 cells, that's 5 watts per cell at the MPP
> (maximum power point), which is not a trivial amount.


If the panel is shorted, it is not at maximum power point.


> The instructions for such tests often include some manner of warning
> not to leave the panels shorted for too long or they might overheat.
> Sometimes, they show a hot cell with an open circuit condition
> (usually when the shading protection diode goes open circuit).
> 
> The tiny panel the OP is using will probably do nothing dangerous if
> the panel is shorted, but I consider it good practice to add the
> overheating warning since there's no clear boundary between what size
> panel is safe and unsafe to short.  In other words, if he burns his
> house down shorting a power source, I would want to at least claim
> that I warned him.
> 
>

Thread

Can a small photocell panel be connected to a flashlight type rechargable battery? oldschool@tubes.com - 2018-10-11 00:32 -0500
  Re: Can a small photocell panel be connected to a flashlight type rechargable battery? <698839253X6D445TD@nospam.org> - 2018-10-11 06:10 +0000
  Re: Can a small photocell panel be connected to a flashlight type rechargable battery? tabbypurr@gmail.com - 2018-10-11 05:51 -0700
  Re: Can a small photocell panel be connected to a flashlight type rechargable battery? George Herold <gherold@teachspin.com> - 2018-10-11 06:18 -0700
  Re: Can a small photocell panel be connected to a flashlight type rechargable battery? dplatt@coop.radagast.org (Dave Platt) - 2018-10-11 10:39 -0700
    Re: Can a small photocell panel be connected to a flashlight type rechargable battery? bitrex <user@example.net> - 2018-10-11 22:41 -0400
  Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-11 12:14 -0700
    Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jasen Betts <jasen@xnet.co.nz> - 2018-10-11 22:34 +0000
      Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-11 19:31 -0700
        Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jasen Betts <jasen@xnet.co.nz> - 2018-10-12 05:02 +0000
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-11 23:05 -0700
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 09:08 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 09:36 -0700
              Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 10:20 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 10:37 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 09:41 -0700
              Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 10:04 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jasen Betts <jasen@xnet.co.nz> - 2018-10-12 19:24 +0000
              Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 18:26 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 22:27 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jasen Betts <jasen@xnet.co.nz> - 2018-10-13 05:32 +0000
        Re: Can a small photocell panel be connected to a flashlight type rechargable battery? John S <Sophi.2@invalid.org> - 2018-10-12 02:12 -0500
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 09:15 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? John S <Sophi.2@invalid.org> - 2018-10-13 15:14 -0500
              Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-14 20:34 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? John S <Sophi.2@invalid.org> - 2018-10-15 20:39 -0500
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-15 21:28 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? John S <Sophi.2@invalid.org> - 2018-10-16 18:08 -0500
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-16 16:29 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-16 16:47 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? John S <Sophi.2@invalid.org> - 2018-10-17 02:23 -0500
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 09:23 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 09:48 -0700
              Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 17:57 -0700
                Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 22:19 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jasen Betts <jasen@xnet.co.nz> - 2018-10-12 19:56 +0000
        Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2018-10-12 07:36 +0000
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? George Herold <gherold@teachspin.com> - 2018-10-12 05:59 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2018-10-12 13:06 +0000
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-12 09:18 -0700
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? Jeff Liebermann <jeffl@cruzio.com> - 2018-10-12 09:44 -0700
            Re: Can a small photocell panel be connected to a flashlight type rechargable battery? <698839253X6D445TD@nospam.org> - 2018-10-12 17:57 +0000
        Re: Can a small photocell panel be connected to a flashlight type rechargable battery? whit3rd <whit3rd@gmail.com> - 2018-10-12 23:23 -0700
          Re: Can a small photocell panel be connected to a flashlight type rechargable battery? gnuarm.deletethisbit@gmail.com - 2018-10-13 04:56 -0700

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