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  • Need help in evaluating replacing my existing solar panels

    Hi. I have an odd situation I need some help resolving. About 12 years ago, we installed a grid-tie solar PV installation with 36 LG 175w panels and a Fronius IG 5100 inverter. This system, has worked well, but never completely eliminated my energy bill as we have a few computer servers and now with 4 kids, burn a lot of energy. But it's saved a ton of money (and the roof has never leaked!), as here in the SF Bay Area, PGE charges an arm and a leg when you get into their band 4 or 5 pricing. The panels are all on the same 2nd story roof and point almost exactly due south, and on a clear day the system generated about 4700W in mid day.

    The IG 5100 recently failed, and in discussions with Fronius, it became clear it was going to be better to replace it with a new inverter than repair the old one, esp since the old one didn't have monitoring. The company that installed it is no longer in business on top of it all. So I got a new fronious primo 5000, and even though its pretty easy to replace myself (the inverter is in the garage, and has an ac disconnect at the panel and a separate dc disconnect next to the inverter), I like to stay compliant with code so I called an electrician to replace it.

    The electrican really didn't want to deal with the inverter programming and such,. and referred me to a solar installer that also does repairs. The issue is apparently that the wiring I have to the panels is not double insulated, which was common a decade ago, but is no longer code with a transformerless inverter like the primo. Furthermore, it appears that you can't find inverters in the 5 KW class anymore, and to redo the wiring to and between the panels would be very expensive, and I should probably replace the panels at the same time if I did that. He said the new primo would work fine if installed, but that it could not be compliant with code, so he wouldn't do it, but agreed it would probably be easy for me to do it.

    So now I am thinking about executing the original plan, and swapping out the inverter myself, which gives me pause as I like to be compliant with code, or basically redoing the entire system and installing new panels, which might be good in terms of reducing my electric bill even more.

    I'd love some advice on how to proceed, and have a few specific questions:

    1) Why is it needed to use double insulated wiring with a transformerless inverter like the primo?

    2) If I do install a new set of panels, does the 30% federal tax credit still apply if I am just replacing an existing system instead of installing one for the first time?

    3) How much cheaper would replacing the panels and wiring cost over a new installation, and could the existing roof mounts be reused? I know a more powerful system would need a bigger inverter, so I would have to factor that in as well.

    4) With 36 panels, I don't think I need to go with an expensive panel like the X21, but I the LG 315W panels seem like a good fit. Do folks have any advice for me in terms of special things to consider if I do go with new panels in a situation like mine?

    Thanks!
    Mike
    Last edited by fresnoboy; 03-19-2016, 12:35 PM.

  • fresnoboy
    replied
    Thanks for the replies. I am getting some bids to upgrade the panels, though I have never liked the idea of microinverters or proprietary technology for the reasons mentioned here. We'll see how much the bill could be and how more power I can generate with that footprint. It might be worth it to get even more power out of the system.

    I am not so sure I'd want to go get the last model of inverter produced that is will soon be unavailable just because it's transformerless and designed to work in my type of system. I guess all the folks like me with the older wiring is not enough of a market for companies to keep producing inverters that work with them. I'd almost go ahead and use the newer Primo instead and deal with the shutdowns in case something becomes grounded on the DC side.

    Grounding on the DC+ side sounds really weird. Sunpower made inverters that did that?

    thx
    mike

    Leave a comment:


  • sensij
    replied
    Originally posted by DaveDE2 View Post
    It's pretty sad that a routine inverter failure can cause someone to have to scrap their entire system and start over after only 10 years. I hope that doesnt happen with my new system. It would kind of blow my cost model.
    I suppose, but anyone installing SolarEdge, in particular, is taking a similar risk. The communication between the optimizers and inverters is proprietary, and if SolarEdge were to get bought out or go under, there is a chance that compatible parts won't be available in the future. As inverters move toward being "smarter" about their grid interactivity, all of today's inverters will become obsolete, and it remains to be seen if wiring standards will change in a way that causes these kinds of problems in the future.

    A decade ago there might not have been a choice, but now, an informed shopper can buy a system that should pay for itself in less than 10 years and hopefully have less heartache in the future if replacement is required.

    Leave a comment:


  • sensij
    replied
    Originally posted by fresnoboy View Post
    Thanks... The confusion was when I talked with Fronius about options to swap the old inverter. The installer I talked to (after I talked to the electrician who didn't want to do a simple swap himself) told me the Sunny Boy 5000 inverters that would be a drop in replacement are no longer in production. The TL series of inverters from them are transformerless I take it? I could always ebay the Primo if I needed to I suppose.

    Yes, those look like the panels the original installer used, and it was Akeena, so you have a very good database indeed! Thanks for looking this up.

    So your recommendation at this point is to try and find an inverter that is plug in capable, or replace the wiring and/or panels up on the roof. If the panels do have USE-2 wires coming off of them, how would that be code compliant, or is it OK if the wiring from the panels is USE-2, but any other wiring gets replaced with PV? Is it possible to replace the wires coming off the panels, or is it required to get new panels in that case?
    Yes, the TL series are transformerless, same problem as the Primo.

    I do think the cleanest solution is to track down a transformer based inverter like the SB5000-US. It might be possible to open up the junction box on the back of the panels and put in new leads, but at that point, just replacing the panels is probably better in the long run.

    I think it would be good to run this by someone in the office that issues permits for your location. You might find them very helpful if you explain your situation, and maybe they can suggest an alternative, or at least confirm what we've looked at here.

    As rough as this situation is... I don't know what all the early Sunpower adopters who require DC+ grounding will do as their inverters begin to fail. I guess it will be a good test of their warranty.

    Leave a comment:


  • DaveDE2
    replied
    It's pretty sad that a routine inverter failure can cause someone to have to scrap their entire system and start over after only 10 years. I hope that doesnt happen with my new system. It would kind of blow my cost model.

    Leave a comment:


  • foo1bar
    replied
    Originally posted by ButchDeal View Post

    You might try getting the permit pack from the install at the county office. It should have some useful information on the wiring and layout as well.
    Might be county, might be city - I don't think he stated what city/area he is in.
    If he's within a city boundary, most likely it's a city permit office.
    But in general, getting the permit information from the building permit office is a very good idea.
    They usually are happy to help a homeowner - but many do charge a per-copy fee so you need to be somewhat prepared for that.

    Leave a comment:


  • sunnyguy
    replied
    True they are discontinued but renvu has sb5000us for $1987 after coupon and there is also one on eBay.

    How much has your output dropped over 10 years? Seems like the best two options are to replace only the inverter or start over from scratch with a higher output system and possibly a new roof. I think there was also a guy somewhere who fixes fronius inverters for around $500.

    Leave a comment:


  • fresnoboy
    replied
    Originally posted by sensij View Post
    I was digging around in the CSI database of installations and am guessing that the panels are actually Kyocera... KC175GT. A couple of installers liked that combination (Sun Power and Geothermal Energy [SPG]; and Akeena) show up in the list with a few 36 panel installations with this equipment at about the right time.

    The installation guide for those panels indicates that the leads are USE-2 (see section 7), which again, was typical then. It is possible the panels were "skip wired", which might mean only the panels leads are used except for the final connection to the combiner box, so there might not be much other wiring up there.

    I can see why the solar installer backed away from this. Really, the cleanest solution would have been to just swap the failed inverter with a Sunny Boy 5000 like I mentioned earlier. If the Primo can't be returned, a conversation with the AHJ would probably be the most appropriate next step.




    The only thing I'd like to point out is that this isn't a problem with "new rules". Prior to 2005 NEC, ungrounded systems above 50 V were not allowed at all. Even if you could use a time machine to send the Primo back to the original installer, they wouldn't have been able to do anything with it. All ungrounded systems (above 50 V) require PV wire for exposed runs on the roof. 690.35 as posted earlier is the only rule that has ever existed.

    Thanks... The confusion was when I talked with Fronius about options to swap the old inverter. The installer I talked to (after I talked to the electrician who didn't want to do a simple swap himself) told me the Sunny Boy 5000 inverters that would be a drop in replacement are no longer in production. The TL series of inverters from them are transformerless I take it? I could always ebay the Primo if I needed to I suppose.

    Yes, those look like the panels the original installer used, and it was Akeena, so you have a very good database indeed! Thanks for looking this up.

    So your recommendation at this point is to try and find an inverter that is plug in capable, or replace the wiring and/or panels up on the roof. If the panels do have USE-2 wires coming off of them, how would that be code compliant, or is it OK if the wiring from the panels is USE-2, but any other wiring gets replaced with PV? Is it possible to replace the wires coming off the panels, or is it required to get new panels in that case?

    Thx!
    Mike




    Leave a comment:


  • sensij
    replied
    Originally posted by fresnoboy View Post

    Got it. So the Primo not only doesn't need the ground fault fuse between the DC- and ground, it actually wouldn't work properly if there was a fuse in the system between the DC - and the frame ground? I did notice in the wiring diagram, the Primo doesn't have an explicit frame ground connector like the IG 5100 did. It sounds like the ground would just not be connected to anything at all if it was hooked up in the normal way, other than maybe the ground coming through the conduit? The wiring diagram does indicate ground from frame and racks is connected to the Primo, just not through an explicit connector it seems.
    Yes, this is all correct. Any connection between the DC conductors and ground (through a fuse or otherwise) will trip the Primo. A ground still needs to be provided to serve as an equipment ground conductor, keeping all metal surfaces in the system at ground potential.

    Leave a comment:


  • sensij
    replied
    I was digging around in the CSI database of installations and am guessing that the panels are actually Kyocera... KC175GT. A couple of installers liked that combination (Sun Power and Geothermal Energy [SPG]; and Akeena) show up in the list with a few 36 panel installations with this equipment at about the right time.

    The installation guide for those panels indicates that the leads are USE-2 (see section 7), which again, was typical then. It is possible the panels were "skip wired", which might mean only the panels leads are used except for the final connection to the combiner box, so there might not be much other wiring up there.

    I can see why the solar installer backed away from this. Really, the cleanest solution would have been to just swap the failed inverter with a Sunny Boy 5000 like I mentioned earlier. If the Primo can't be returned, a conversation with the AHJ would probably be the most appropriate next step.


    Originally posted by DaveDE2 View Post
    So just to summerize at the point:
    - If either the panels or panel wiring is USE-2 and not PV, then replacing the inverter with a Primo is not code compliant under the new rules.
    - If they both are PV, then installing a Primo is code compliant.
    - If anything in the panel wiring uses USE-2 and the the OP decides to replace the inverter with a Primo, the upgraded system will work just fine but the system will not be code compliant. Correct?
    The only thing I'd like to point out is that this isn't a problem with "new rules". Prior to 2005 NEC, ungrounded systems above 50 V were not allowed at all. Even if you could use a time machine to send the Primo back to the original installer, they wouldn't have been able to do anything with it. All ungrounded systems (above 50 V) require PV wire for exposed runs on the roof. 690.35 as posted earlier is the only rule that has ever existed.

    Leave a comment:


  • DaveDE2
    replied
    So just to summerize at the point:
    - If either the panels or panel wiring is USE-2 and not PV, then replacing the inverter with a Primo is not code compliant under the new rules.
    - If they both are PV, then installing a Primo is code compliant.
    - If anything in the panel wiring uses USE-2 and the the OP decides to replace the inverter with a Primo, the upgraded system will work just fine but the system will not be code compliant. Correct?

    Leave a comment:


  • ButchDeal
    replied
    Originally posted by fresnoboy View Post
    Nope, at least not without climbing on the roof and looking. The work order from 2006 didn't get that specific.

    thx
    mike
    You might try getting the permit pack from the install at the county office. It should have some useful information on the wiring and layout as well.

    Leave a comment:


  • fresnoboy
    replied
    Nope, at least not without climbing on the roof and looking. The work order from 2006 didn't get that specific.

    thx
    mike

    Leave a comment:


  • DanKegel
    replied
    Do you happen to have the exact model number for the LG175's you have? e.g. LG200R1C-G2 ?

    Leave a comment:


  • fresnoboy
    replied
    Originally posted by sensij View Post
    A equipment ground conductor to ground the frames on the modules and the racking is required, and is probably the ground wire you see.

    THWN-2 is appropriate for the run from the combiner to the inverter, in conduit or physically protected. You can leave that run along, except if you increase the capacity of the array it might be too small to carry the additional power without help.

    The USE-2 or PV wire should only be in the unprotected runs between panels and to the string combiner, where it would transition to conduit with the THWN-2.

    One other slight concern would be the type of wire used on the panel leads. I couldn't find any documentation on a LG 175 W panel to see what might have been used. All panels going up today have PV wire leads.
    Got it. So the Primo not only doesn't need the ground fault fuse between the DC- and ground, it actually wouldn't work properly if there was a fuse in the system between the DC - and the frame ground? I did notice in the wiring diagram, the Primo doesn't have an explicit frame ground connector like the IG 5100 did. It sounds like the ground would just not be connected to anything at all if it was hooked up in the normal way, other than maybe the ground coming through the conduit? The wiring diagram does indicate ground from frame and racks is connected to the Primo, just not through an explicit connector it seems.

    Thanks!
    Mike


    Leave a comment:

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