Damaged PV Panels (Lightning Strike)

Hi, its been a while , would like a little bit of advice on a situation I came across yesterday.

I was asked to go troubleshoot a system, which had received a direct lightning strike to the house. Apparently every electrical products was killed including the inverter , old DR unit and Charge Controller and generator

New equipment was fitted a secondhand Xantrex PS 24v Inverter charger. The couple were not insured insured at this time and footed the bill . But they were getting no power from the PV array , didnt have any money to fix so lived off genset and batteries

There solar array consisted of 6 x Kyrocera 120 wp 12 volt panels wired in 3 strings of two series connected panels.

Shortly after this a storm blew the panels apparently over and two units were smashed - damaged. This time they were insured and a company used by the Insurance People provided 2 new panels again very similar Kyrocera 110 wp standard 12v modules and a new Stecca PR3030 PWM CC.

Job done new panels installed charge controller fitted, everything OK Bill Bodger from the approved Insurance Co leaves.

Owner over next week or so the owners becomes unhappy with their PV performance and are running her generator a lot more prior to direct Lightning Strike, a call to Bill Bodger, proves fruitless doesnt want to know. Blames the seconhand invertor and generator. Refuses to visit.

So I go , Overcast day but the sun is visable quick check no power current in to the CC and a voltage reading of about 20v. Half combined arrays VOC

Quick check of array and individual panels are as follows

String 1 New Panels indidually checked VOC, ISC OK when wired into PR3030 cc in series for nominal 24v Power flows everything OK

String 2 (Lightning Strike Victim) One Panel OK VOC, second panels showing half VOC around 9-10 Volts

String 3 (Lightning Strike Victims) One Panel Half VOC around 9-10 Volts Second Panel dead no volts VOC

String One was rewired to CC and Panels , CC working fine.

A Check inside of one of the Panels producing 9 volts approx half VOC as you can seen from the picture of the junction box there are 4 terminals each pair connected with 3 diodes, A test of these diodes showed one set appears OK, 100% continuity one way, open circuit the other way. However the other pair read 100% continuity one way and a reading of 25 ohms the other.

Im no electronics expert, I know a diode is a one way conductor and I suspect that the damaged diodes are responsible for the failure in the panels VOC reading, hopefully

The diodes appear to be spot welded on to the terminals,

The details I could read on the diodes of which there are clearly three were RM130

The picture shows the blue wire (negative connection) with the small metal strip and bolt removed to show the spot welded diodes.

The top two connections show the metal strip connect over the diodes in place and the Positive Connection Fixing bolt removed.

My thoughts are that if I clip out the damaged 3 diodes, replace if possible with one suitable larger diode using the pairs bolt connection, then for little cost I might get lucky and regain the damaged panels for this couple ?

Need your advice and suitable replacement Diode-
As I said Im no expert with electronics and components, but if there is any other testing I can do with my DMM and DC Clamp meter I welcome suggestions, the owner is obviously going to try the diode replacement as its worth the shot, unless you tell me different. All views comments, suggestions apprieciated.



  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: Damaged PV Panels (Lightning Strike)

    On KC120's, the Diodes are simply attached by compression of the screw and plate. All you have to do is remove the diodes ( remove two screws ) and see if its the panel or the Diodes.

    What you will probably find is one or more of the three are shorted, not uncommon and any 3 amp diode will be fine for replacement as its only used when you have shading of the cells
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Damaged PV Panels (Lightning Strike)
    My thoughts are that if I clip out the damaged 3 diodes, replace if possible with one suitable larger diode using the pairs bolt connection, then for little cost I might get lucky and regain the damaged panels for this couple ?
    Guppy is correct, the diodes are just self attached and a flat bladed screwdriver and a light tap of a hammer will loosen them. Actually the panel should work without the diodes in place, but you should replace them anyway as they bypass any panel shading. If they are older KC120's remember that they manufactured a bad batch around year 2000. My neighbor has had 9 of his panels go out.
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Damaged PV Panels (Lightning Strike)

    Thankyou very much for SG and Mike for your replies. Ive seen some diodes available that are as follows

    IN5404 3 Amp 400v

    Would these be suitable

  • mike95490mike95490 Solar Expert Posts: 9,572 ✭✭✭✭✭
    Re: Damaged PV Panels (Lightning Strike)

    putting diodes in parallel, is somewhat un-certain, as they won't share voltage equally, you will have 3 different Vf. But it seemed to work before, so it's worth a try again. Be sure when installing them, the bars are clean and no corrosion, same with diode leads.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Damaged PV Panels (Lightning Strike)

    Was solar system grounded? Where exactly did the lightning bolt hit?
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Damaged PV Panels (Lightning Strike)

    It was a direct hit to the chimney stack and the inverter was in an outbuilding near & below the stack, also the property was grounded in 2 locations one near the house and one near the generator shed 70 ft away which is also a bad design . Ive told them to have only one common ground point.

    They are on an elevated position there closest neighbors are commercial wind turbines. System has been running about 7 years
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Damaged PV Panels (Lightning Strike)

    you can pop those diodes out of there and see what shakes for output before replacing them. the lightning may have welded them to the metal somewhat and i can see that the whole thing carried a great deal of current that the insurance guy can't claim was from the inverter or anything else. he is not honoring the insurance that they are paying for just because he don't want to pay out. the insurance man is not qualified to judge electrical things as to damage causation let alone function. all one would need is an electrician to verify the cause of the damages that would be willing to sign an affidavit to that effect and if he doesn't honor it then he can sue them. that needs to be done before you do anything to it so nobody claims you did something to it.
    i question if the pvs themselves aren't fried too seeing as to how much current passed near those diodes with the plastic semi-disfigured from melting.
  • wooffiwooffi Registered Users Posts: 18 ✭✭✭
    Re: Damaged PV Panels (Lightning Strike)

    I am new to this forum, just a comment...

    I got very lucky about three months ago lightning hit my property, all power was out in the surrounding properties.

    My Xantrex shot down, nothing was damaged except the Xantex Charge Controller.

    Replaced it with a well grounded Outback FlexMax (needed more amp anyway)

    Glad I found this forum, felt always like the lonely wolf here in West Tennessee.

    Off the grid since 1990. Done every possible mistake at least twice, too small of a solar array, solar panels in the wrong place, golf cart batteries, used forklift batteries, cheap generators, sad performing Onan propane generator, wind turbine amongst tall trees, you name it we have done it.

    FINALLY in 2016! A 1576 ah bank, my good old reliable 4KW Kubota Diesel, one of the last US build Xantrex W4024 inverter, going since 2000, Outback 80 amp charge controller, updated to 2400 watt solar array in 2019 (only good for 5 hours, don’t want to loose my trees).
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Damaged PV Panels (Lightning Strike)


    I returned to the `property with the 3 damaged panels removed the shorted diodes and replaced with new , two of the panels returned to spec 19 v VOC approx however one panel didnt recover and only shows 9-10 volts. She is now seeing 14 amps going into batteries previously only 6a

    So I guess 2 out of 3 for the cost of a few diodes and my time is a result for the client.

    A big thank you to all the contributors on this post.

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Damaged PV Panels (Lightning Strike)

    i guess it's good and bad news. i guess they'll need to replace the one pv then. so are they going to take any steps to possibly thwart that from happening again?
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