Lloyd:
Thank you for your reply. That is how I read the instructions for all of the aforementioned MLPE devices. I think there is a flaw in the logic here, at least for the NEP and Tigo products. It is because both manufacturers offer rail or frame mounting options. This is significant for this reason: If you are frame-mounting an MLPE device it is convenient to connect PV leads to the MLPE first and you can easily comply with the instructions. If, however, you are rail-mounting the MLPE it is quite inconvenient to not be allowed to interconnect the MLPE devices before connecting the PV. You really need to complete all of the hardware and wiring infrastructure associate with your mounting system before you bring your modules to the roof. It is very awkward to be juggling a panel on the roof to connect it to rail-mounted MLPE before you are allowed to interconnect the rail-mounted MLPE devices. It is my opinion that if your MLPE devices cannot be interconnected, you should not offer a rail-mount option. It is important that we use proper terminology for these parts of the system. “Interconnecting” and “home-runs” are different things: Interconnecting leads are between devices. Home-runs are leads run between the ends of strings of devices and the terminating equipment. NEP equated these in their quick start guide and this caused confusion. I spoke to George with NEP today about this. I presented this dilemma and he seemed to understand the conflict. George told me the concern is that if an installer connected a PV panel to the series-string output of the PVG units, damage to the MLPE unit could occur. They do have the same MC4 connectors so this is possible. I get the concept that even the dumbest mistakes are possible, but it would be hard to confuse the different connections. The PV inputs are quite short and the series-string connections are abundantly long. Also they are clearly labeled. George told me that as long as the home-runs were left unterminated, the interconnecting leads can be connected prior to connecting PV without risking damage to the PVG units. As always, the devil is in the details. Success is achieved in understanding and dealing with the details. William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 *From:* Lloyd Hoffstatter [mailto:[email protected]] *Sent:* Tuesday, November 12, 2024 7:44 AM *To:* [email protected]; RE-wrenches *Subject:* RE: [RE-wrenches] NEP PVG wiring Hi William, The RSD installation instructions mirror those of TIGO and APSmart per connection order of PV to RSD first. Best regards, Lloyd Lloyd Hoffstatter, M.S. Applied Solar Energy Director, Sunstruck Consulting *[email protected] <[email protected]>* 845-657-8132 (office) 914-844-3404 (cell) *From:* RE-wrenches <[email protected]> *On Behalf Of *William Miller via RE-wrenches *Sent:* Monday, November 11, 2024 11:30 PM *To:* RE-wrenches <[email protected]> *Cc:* William Miller <[email protected]> *Subject:* [RE-wrenches] NEP PVG wiring Friends: I am repairing a site with NEP PVG RSD devices. We will be removing all of the modules and finding out why the system is underperforming and why 2 of the units are not reporting. The quick start guide includes this line: PVG’s PV-lead pairs must be connected to PV modules before connecting homerun cables between RSD device. I find this wording confusing. Homerun cables do not connect between RSD devices, home runs connect to the PV input on an inverter (Soul-Arc in this case). I wish to rail mount the PVG RSD devices, connect the series wiring between these modules and then connect the PV. Can I interconnect the PVG units prior to connecting the PV modules? This sure would make the process easier. Thanks in advance for in any input on working with these units. William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.millersolar.com_&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=p2tHyHEAjVe2zSh4C_236V4KkHnn0z0ynUvWz0mobds&m=Sj6SvGiGAeDHb1dV0napuS0qhQ9nlBiveGTpGaibMKwEylmjU3_fIw0-VKruQ-jo&s=DC5TfZLJCY1FTLE0G9RSxAQIvPgwzSR54I9_gSu5gJM&e=> CA Lic. 773985
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