Need to replace a small grid tie inverter attached to older PV modules ,grounded array & 2 mppt - under
Cannot find a isolated inverter around 3.6k The wires at modules are not PV wire, so cannot use any TL version...
Comments
Hello Gail,
What are the modules that you currently have installed? It's my understanding that the +/- leads out of the modules j-boxes are not PV wire, is that correct? The reason I ask, as I'm sure you are already aware, is that for transformeless inverter this type of wire is required coming out of the modules. If their wiring is not PV wire, then I am stuck at the moment in trying to match you with an inverter that has dual MPPT channels and contains an isolation transformer.
I am happy to do some more digging for you, but having a little more information about those modules, the number in each string and the orientation of each array will help me to better understand your system.
Yes Adam, I am fairly certain that the Schuco SP-158 watt modules do not have PV wire--at the time it was exciting to have conductors from a molded j box and MC3 connectors ! Powerone/ ABB used to have a 3.6k dual mppt isolated but no longer available with the need to push to newer TL versions.( and some say the quality has gone downhill anyways..) Your suggestions would be appreciated...
one array has 12 flush mount on roof at 20 deg. tilt, the second array is on another surface: 8 pc on tilt-up rack at 40deg. tilt.
lower start voltage is also key- in high temp. the PV would be contributing about 20 volt DC...( i.e. 160 vdc on shorter string)
Thanks Gail, I spoke with Andrea just a bit ago about this and one of your other projects to discuss some options that are out there. I assigned myself to your case so that if you need anything or have any questions Andrea and I can guide you through them.
Thanks Adam,
On the other project, I spoke with Kaco directly and they are no longer approving the Sunlink add-on AFCI for use with their 1.5kW 1502-xi-US.- so one of the possibilities suggested by Greentech Renewables is no longer an option.
I expect that the problem of finding equipment for grounded systems will be growing as more inverters are needing to be replaced now at a ten year mark and that the industry has so quickly shifted to mostly transformerless equipment.
I still need a solution for the above issue of a small dual channel MPPT, or, a means to use TL with older PV modules that were installed without PV wire from the manufacturer.
Yes, that's true. They have come up with their own that is incorporated in all of their new xi models (Link)
For the above project's dilemma of dual MMPT inverter with isolation transformer, there are a couple of possibilities that can be employed to solve the issue. Sourcing an outmode inverter has proved futile. So one option could be to use micro-inverters that contain isolation transformers. I feel that would create more work to integrate because of the wiring and having to remove module to make connections. Ultimately it will add greater cost to replace the old inverter with these.
My other thought was to integrate two smaller inverters to combine 8 of the Schuco's on a 1.5kW and 12 on the other 2.5kW. Of course this solution need not use Kaco as the manufacturer, however they have a very low price point that does make them favorable.
Unfortunately with the rapid changes in inverter technology over the last 10 years, and the almost total lack of discussion of O&M issues, many older systems will not have a drop in inverter replacement option available. That means starting from scratch and redesigning the stringing of the existing modules to work with inverters currently available. Hopefully inverter manufacturers will not completely stop making isolated inverters.
Yes, it is ironic that the modules are intended to have the 25 year life ,at minimum, but must apparently be retired at 10 years because they are not considered "compatible" with the inverters available for mid-term replacement.
Adam, you mention Kaco as a possible source of small inverters, but they are also now going to just the transformerless Models. I am now seeking another approach to meet the NEC code by looking for an approved "raceway" which can protect the non-PV wire coming from the molded jbox--maybe someone has a suggestion for a retrofit
Is There a "wrap" which can meet the intent of the code by providing increased protection from possible fault situations that may arise from use of the original non-PV wire conductors. SnapNRac rail has a channel often used for wire management, but it is not listed for use as a raceway. Does anyone know of a UL listed "add-on" raceway??
Gail, The PVI 1800 might be the exact model you are looking for if 150-400VDC range, negative grounded is correct. I don't know if Greentech Renewables still sells these but we sure have them in stock! Call Jonathan or me (978-771-6574) anytime. - James Worden, Solectria, A Yaskawa Company, www.solectria.com
Gail, I just checked and we also still have new stock in PVI 4000 if you can use one inverter with one MPPT zone and 200-600VAC range. Two of the PVI 1800s would work great if you must have two MPPT zones. Both these models are transformer isolated. The new 3800-7600 line is transformerless - James Worden, Solectria, A Yaskawa Company, www.solectria.com
Thanks for continuing the conversation. Gail, I will follow up with Solectria to pose the questions we discussed earlier today. James, expect an email from me in a few minutes. Have a great day !
Comments
Hello Gail,
What are the modules that you currently have installed? It's my understanding that the +/- leads out of the modules j-boxes are not PV wire, is that correct? The reason I ask, as I'm sure you are already aware, is that for transformeless inverter this type of wire is required coming out of the modules. If their wiring is not PV wire, then I am stuck at the moment in trying to match you with an inverter that has dual MPPT channels and contains an isolation transformer.
I am happy to do some more digging for you, but having a little more information about those modules, the number in each string and the orientation of each array will help me to better understand your system.
Thanks,
Adam
Thanks Gail, I spoke with Andrea just a bit ago about this and one of your other projects to discuss some options that are out there. I assigned myself to your case so that if you need anything or have any questions Andrea and I can guide you through them.
Gail,
Yes, that's true. They have come up with their own that is incorporated in all of their new xi models (Link)
For the above project's dilemma of dual MMPT inverter with isolation transformer, there are a couple of possibilities that can be employed to solve the issue. Sourcing an outmode inverter has proved futile. So one option could be to use micro-inverters that contain isolation transformers. I feel that would create more work to integrate because of the wiring and having to remove module to make connections. Ultimately it will add greater cost to replace the old inverter with these.
My other thought was to integrate two smaller inverters to combine 8 of the Schuco's on a 1.5kW and 12 on the other 2.5kW. Of course this solution need not use Kaco as the manufacturer, however they have a very low price point that does make them favorable.
Adam
Unfortunately with the rapid changes in inverter technology over the last 10 years, and the almost total lack of discussion of O&M issues, many older systems will not have a drop in inverter replacement option available. That means starting from scratch and redesigning the stringing of the existing modules to work with inverters currently available. Hopefully inverter manufacturers will not completely stop making isolated inverters.
Yes, it is ironic that the modules are intended to have the 25 year life ,at minimum, but must apparently be retired at 10 years because they are not considered "compatible" with the inverters available for mid-term replacement.
Adam, you mention Kaco as a possible source of small inverters, but they are also now going to just the transformerless Models. I am now seeking another approach to meet the NEC code by looking for an approved "raceway" which can protect the non-PV wire coming from the molded jbox--maybe someone has a suggestion for a retrofit
Is There a "wrap" which can meet the intent of the code by providing increased protection from possible fault situations that may arise from use of the original non-PV wire conductors. SnapNRac rail has a channel often used for wire management, but it is not listed for use as a raceway. Does anyone know of a UL listed "add-on" raceway??
Gail, The PVI 1800 might be the exact model you are looking for if 150-400VDC range, negative grounded is correct. I don't know if Greentech Renewables still sells these but we sure have them in stock! Call Jonathan or me (978-771-6574) anytime. - James Worden, Solectria, A Yaskawa Company, www.solectria.com
Gail, I just checked and we also still have new stock in PVI 4000 if you can use one inverter with one MPPT zone and 200-600VAC range. Two of the PVI 1800s would work great if you must have two MPPT zones. Both these models are transformer isolated. The new 3800-7600 line is transformerless - James Worden, Solectria, A Yaskawa Company, www.solectria.com
Hi James and Gail,
Thanks for continuing the conversation. Gail, I will follow up with Solectria to pose the questions we discussed earlier today. James, expect an email from me in a few minutes. Have a great day !
Andrea, sure. James Worden