[RE-wrenches] Diode Failure

Exeltech exeltech at yahoo.com
Mon Oct 20 22:07:38 PDT 2014


"A diode is a diode." ???????

Not so.

That's like saying a solar panel is a solar panel .. or a tire is a tire.

If you can get the identical part # .. then replace it.  Don't go out and just use any diode.

The diodes in PV are commonly a Schottky barrier diode .. designed to minimize voltage drop, reduce energy loss .. and operate cooler than "ordinary" diodes when they're conducting.  Even something as simple as how they're soldered or otherwise attached is also very important, as that aspect is also used to help dissipate the heat generated by losses within the diode when it's conducting current.  To that point, diodes are often rated to operate up to 175C (nearly 2X that of boiling water).

Diodes have specific voltage and current ratings.  If you can't replace a diode with an identical part .. then you'll have to use as near a match as possible.  Never go LOWER in ratings .. but if you go too much above .. it may not work properly (or long-term reliably) either.

Corey .. contact me off list with the diode part number and I'll see what I can do to assist.


Dan


--------------------------------------------
On Mon, 10/20/14, Chris Mason <cometenergysystems at gmail.com> wrote:

 Subject: Re: [RE-wrenches] Diode Failure
 To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
 Date: Monday, October 20, 2014, 6:38 PM
Corey,
A diode is a diode. Get an electronics technician to identify the correct part and source it.

On Mon, Oct 20, 2014 at 4:51 PM, Corey Shalanski <cshalanski at joule-energy.com> wrote:

    Wrenches,

    Since my previous post (see below) we have recovered the faulty modules and are now looking to replace the diodes in order to make them functional again. I have had no success sourcing replacement diodes from the original module manufacturer, Mage Solar.

    Can anyone recommend a source for replacement diodes?

    --
    Corey Shalanski
    Joule Solar
    New Orleans, LA

    ᐧ
    On Tue, Aug 5, 2014 at 10:27 AM, <re-wrenches-request at lists.re-wrenches.org> wrote:


        Message: 10
        Date: Tue, 5 Aug 2014 09:03:09 -0500
        From: Corey Shalanski <cshalanski at joule-energy.com>
        To: RE-wrenches at lists.re-wrenches.org
        Subject: [RE-wrenches] Diode Failure
        Message-ID:
                <CA+SmqZ1C7KSZuQnVzQr0MMuX3F2dT6YDuM40iseCzr2EJRgA+Q at mail.gmail.com>
        Content-Type: text/plain; charset="utf-8"

        Wrenches,

        We recently were contacted by a customer who reported a lightning strike
        close to his house. His online monitoring revealed that 30 of 35
        microinverters simultaneously stopped producing power. On initial visit to
        the jobsite we measured Voc on many modules - either 12V or 24V instead of
        rated 36V. On a second visit we discovered that bypass diodes - either 1 or
        2 corresponding to observed voltage loss - had failed on each of the faulty
        modules.

        My question is: Can anyone support the theory that a nearby lightning flash
        can cause mass bypass diode failure?

        --
        Corey Shalanski
        Joule Energy
        New Orleans, LA




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