Repairing lightning damaged solar panels

Greetings Solarites,

Sorry my first post is a desperate cry for help...not much information on line for the situation I have thrust myself into. I work for an electrical company and have acquired 40 solar world 240 watt panels that were part of an FDOT solar field that got hit by lightning here in Florida. With a multimeter it's a mixed bag. Some panels read almost no voltage and some read close to the rated voltage of 33 or so volts. The rest read either 10-12 or 20-22 vdc. It looks like these panels are set up as three solar arrays of 12 vdc each wires in series. The junction boxes are of two types. The larger type junction box has the leads screwed to terminals. The other is a completely sealed type only giving me limited access to the terminals to add diodes. Both are sealed in silicon that I had to scrape out to access metal posts. The junction box of the first type shows swelling of the plastic on the bottom of the box that is somewhat inaccessible without cutting apart. The plastic backing material on some panels has swollen like a small balloon also at the underside of the junction box, I have not popped them. The smaller sealed junction boxes show no damage whatsoever but they are still not putting out rated power.

The panels all look perfect from the front and I have seen no burn marks. My goal is to be able to remove the old junction boxes without destroying the embedded wires so they can be rewired. I am of the belief most of the damage is at the box and the internal box connections since that is where the heat damage seems to be. It looks to be a very painstaking process to cut into the hard plastic to find the wire connections. May be a heat knife would work. The pdf file of these panels shows they have diodes but I do not see them. This panel may have not been shipped with them or they may be hidden under sealed plastic. I need info on how best to proceed doing the least damage possible. I have found very limited information on replacing these new sealed junction boxes on-line and figured I would consult the PROs. I do understand how critical and difficult it is to seal repairs from water damage.

Thanks for any help in advance. I will answer any questions you have as promptly as possible.

Comments

  • pleppik
    pleppik Solar Expert Posts: 62 ✭✭✭✭
    Re: Repairing lightning damaged solar panels

    I'm not even remotely a pro, but I'm going to hazard that the best you may be able to do cost-effectively is triage. Solar modules aren't designed to be repaired, they're designed to keep the elements out for decades.

    With new modules selling for under $1/watt, if you spent more than a few hours repairing each module it will cost FDOT more than just buying a replacement. And odds are the repair won't last anywhere near as long as a new module.

    So my layperson's suggestion is to test the Voc and Isc of each module and put the ones which are in-spec back in service no matter how ugly the junction boxes, and discard the rest.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Repairing lightning damaged solar panels
    Greetings Solarites,

    Sorry my first post is a desperate cry for help...not much information on line for the situation I have thrust myself into. I work for an electrical company and have acquired 40 solar world 240 watt panels that were part of an FDOT solar field that got hit by lightning here in Florida. With a multimeter it's a mixed bag. Some panels read almost no voltage and some read close to the rated voltage of 33 or so volts. The rest read either 10-12 or 20-22 vdc. It looks like these panels are set up as three solar arrays of 12 vdc each wires in series. The junction boxes are of two types. The larger type junction box has the leads screwed to terminals. The other is a completely sealed type only giving me limited access to the terminals to add diodes. Both are sealed in silicon that I had to scrape out to access metal posts. The junction box of the first type shows swelling of the plastic on the bottom of the box that is somewhat inaccessible without cutting apart. The plastic backing material on some panels has swollen like a small balloon also at the underside of the junction box, I have not popped them. The smaller sealed junction boxes show no damage whatsoever but they are still not putting out rated power.

    The panels all look perfect from the front and I have seen no burn marks. My goal is to be able to remove the old junction boxes without destroying the embedded wires so they can be rewired. I am of the belief most of the damage is at the box and the internal box connections since that is where the heat damage seems to be. It looks to be a very painstaking process to cut into the hard plastic to find the wire connections. May be a heat knife would work. The pdf file of these panels shows they have diodes but I do not see them. This panel may have not been shipped with them or they may be hidden under sealed plastic. I need info on how best to proceed doing the least damage possible. I have found very limited information on replacing these new sealed junction boxes on-line and figured I would consult the PROs. I do understand how critical and difficult it is to seal repairs from water damage.

    Thanks for any help in advance. I will answer any questions you have as promptly as possible.

    1. Some of the interconnecting wires within the panel are behind the cells and may be damaged without it being visible from the top.
    2. The swollen boxes are probably related to burned out diodes. This could have been the result of lightning induced currents or the indirect result of cell damage forcing the diode(s) to carry current continuously instead of just in case of shading.
    3. If there is any damage inside the sealed area of the panel itself, forget it as you will never be able to reseal the panel effectively after any repair. If there is a separate seal between the box and the inside of the panel, you may be OK.
    4. The wires from the cells to the junction box may be just thin metal foil, so be careful. You may need to sacrifice one panel to see what is inside the junction box before proceeding carefully with others.

    The panels that do not put out full voltage into an open circuit almost certainly have a short circuit, either a shorted diode or insulation breakdown inside the panel.
    Panels that put out full voltage open circuit but not full amps into a short circuit almost certainly have cell damage and open-circuited diodes.
    SMA SB 3000, old BP panels.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Repairing lightning damaged solar panels

    Welcome to the forum.

    Those junction boxes are well-sealed, eh? They need to be to keep the elements out.

    Inside them you will find connectors to various segments of the panel, and bypass diodes. Panels that have been knocked out by nearby lightning strikes quite likely have damaged diodes. They can be blown open, which you won't notice, or shorted which will kill the power from whatever segment they are meant to bypass.

    Now for the really bad news: the PV cells themselves are diodes and can suffer the same fate. It's what happens when you subject a component designed to handle 600 Volts maximum to the tens or even hundreds of thousands of Volts available from lightning. This means that even if you remove the shorted bypass diodes the cells may still produce nothing.

    How are you going to open the boxes? I'd use a rotary or oscillating saw to slice around the top edges. Then unsolder the bypass diodes (probably three) and check the cell segments individually for output under light. You should get a Voc reading. If not, it's trash. If you do get Voc then you can check them under full, direct sunlight for current output. Just because the achieve Voc doesn't mean they actually produce any power. At that stage you may have a working panel (once you install some new bypass diodes) or maybe just a panel segment. How well it will work can be another matter as the cells may function but not at prime specs, including shunt resistance.

    On the whole PV panels aren't very good candidates for repair.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Repairing lightning damaged solar panels

    Sadly, talking to a glass company on how to repair a broken mirror, will give you an idea of the ease of repair :cry:
    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 ,

  • BULLETDODGER
    BULLETDODGER Registered Users Posts: 2
    Re: Repairing lightning damaged solar panels

    Thanks to everyone who responded.

    The cells look to be in too good of shape not to attempt something. The rotary saw idea is a great tool for what I need. Almost all the panels put out something. Is it alright to hook up panels even though they are not producing full rated power. Quite a few are 20-22 volts. Also, slightly off subject, what off grid inverter to you guys consider the most trouble free.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Repairing lightning damaged solar panels

    20-22 Volts open circuit is a good sign, but not the whole story. If using panels that don't put out to spec it depends on why they don't put out: if you can bypass bad cells manually, connect the good ones in series and come up with 'correct' Voltage that's one thing. But if you have a shorted diode bypassing a segment then that will always be a problem, as would dead cells in series. Whatever is defective has to be weeded out, and the result has to be matching panels of some configuration or else you will have trouble.

    Unquestionably the most dependable off-grid inverter is the Outback FX/VFX series. It costs a lot of money ($2,000 range). There are other inverters with fewer features which cost less and are also dependable, such as the Exeltech. Xantrex's Prosine series is good stuff (not the XW or Conext SW however). A good 'bargain' brand is the Samlex/Cotek line. Much depends on what you need the inverter to do.
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Repairing lightning damaged solar panels

    Cariboocoot I would dispute that claim"" Unquestionably""??? big claim.I have tested over the years just about every commercially available and many not available to the public but am still hesitant to give Brand "X" as the best available . Im not saying the Outback FX/VFX are not good,They are.
    Unquestionably the most dependable off-grid inverter is the Outback FX/VFX series. It costs a lot of money ($2,000 range).
    There are others such as Victron. they are equal to.. or better than just about anyones..
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Repairing lightning damaged solar panels

    Definately would question that Outback is best. I use them both and the XW is probably the most lightning proof inverter out there. When coupled with GFI and escalating faults the unit will shut down in a nearby strike. I have seen this several times. Outback and The XW are all I would use in a home as they are the only two who build a decent offgrid system where all the devices talk to each other. Maybe add the Sunnyboy island to the list.
    john p wrote: »
    Cariboocoot I would dispute that claim"" Unquestionably""??? big claim.I have tested over the years just about every commercially available and many not available to the public but am still hesitant to give Brand "X" as the best available . Im not saying the Outback FX/VFX are not good,They are.
    Unquestionably the most dependable off-grid inverter is the Outback FX/VFX series. It costs a lot of money ($2,000 range).
    There are others such as Victron. they are equal to.. or better than just about anyones..
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Repairing lightning damaged solar panels

    John is correct that the Victron equipment has a good reputation - overseas. They do not have a strong North American "presence" however, so there's not a large installed base to go by. The NA models are different from the European versions. However they are not better than Outbacks.

    As for Dave's remarks about XW's being "lightning proof" I can only assume he means you can't tell the difference between an XW that's been 'bricked' by lightning and one that's been 'bricked' by the many built-in flaws. There's no magic components inside that will keep them from frying in a storm, but there's plenty of buggy firmware inside to stop them from working right out of the box.

    I stand by my statement. I do not work for NAWS or any other company. I do not sell equipment. I fix systems, including those installed by others.
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Repairing lightning damaged solar panels

    Cariboocoot Idont want to get into a arguement with you and have bad feelings between us,, But if you state "unquestionably" that something is better than all others of same type. Then that has to be meaning ALL others from every country. You cant give that answer if only against ones available in USA unless you state you only mean USA.. You do agree that the Victron is a good item but you then dismiss it by saying they dont sell well in USA .. So your answer stands..
    Ihave tested many that are equal or better in some respects than Outbacks.. Every inverter has its good and bad points .. What is important to one user may not be so important to another..
    Reliability is another issue.. All inverters have a fail point if overloaded, Some that overload point is higher than others..
    Example s (Madeup figures.. dont quote them) Outback xxxx can withstand overload of 25% before shutdown . Brand x can withstand 40% before shutdown. Now to some users that would make it more reliable.. The Outback may work as it should at -20deg C.. Brand X may shut down at -15 deg C .To some that means its more reliable..

    Its why Isaid I would be very hesitant to state any particular inverter was "unquestionably " the best.

    Two other very good inverters .are from Diehl AKG ,,Germany and Tortech Australia..are probably not available in USA so you cant know if they are better or only equal or below the Outbacks.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Re: Repairing lightning damaged solar panels

    The XW system is based on digital signal processing and the Outback (not the radian) is a generation older and does not have the ability to shut down before it is destroyed by lightning. The XW is not lightning proof for sure just a better chance of making it through the night. If I had problems with either Outback or the XW I would not use them. My friend in Austrailia does have a Victron but I do not know if they make a whole solar based system that can be controlled from one display/panel.
    john p wrote: »
    Cariboocoot Idont want to get into a arguement with you and have bad feelings between us,, But if you state "unquestionably" that something is better than all others of same type. Then that has to be meaning ALL others from every country. You cant give that answer if only against ones available in USA unless you state you only mean USA.. You do agree that the Victron is a good item but you then dismiss it by saying they dont sell well in USA .. So your answer stands..
    Ihave tested many that are equal or better in some respects than Outbacks.. Every inverter has its good and bad points .. What is important to one user may not be so important to another..
    Reliability is another issue.. All inverters have a fail point if overloaded, Some that overload point is higher than others..
    Example s (Madeup figures.. dont quote them) Outback xxxx can withstand overload of 25% before shutdown . Brand x can withstand 40% before shutdown. Now to some users that would make it more reliable.. The Outback may work as it should at -20deg C.. Brand X may shut down at -15 deg C .To some that means its more reliable..

    Its why Isaid I would be very hesitant to state any particular inverter was "unquestionably " the best.

    Two other very good inverters .are from Diehl AKG ,,Germany and Tortech Australia..are probably not available in USA so you cant know if they are better or only equal or below the Outbacks.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net