Re: [RE-wrenches] Question re Midnite surge arrestors

[Allan Sindelar]

Ryan, I may have found the answer to my original post, but it raises more questions. I wrote that these were MV units (MNSPD300), but I checked with my lead tech and learned that in both cases he used LV units (MNSPD115). Could this be the reason? He told me that he has used the LV with 120V inverters and the MV with 120/240V inverters. The instruction manual states that the LV units are designed to be used on nominal 90VAC and 115VDC circuits, and have a Maximum Continuous Operating Voltage of 180V. The manual states: "The MidNite Solar SPD voltage rating should be chosen according to the nominal voltage of the system. Do not install an SPD with Maximum Continuous Operating Voltage (MCOV) below the nominal voltage of the system; this will deteriorate the SPD and making it unavailable when you most need it." If this is true, then the LV (with its 180 MCOV) should be fine at 120VAC. The instructions are confusing: should we use an MNSPD115 or an MNSPD300 with 120VAC output? And in this case, could this be the cause of the failure-to-sleep problem? If we should be using the MNSPD300 with 120VAC inverter output, then the description on the Midnite website is confusing at best. It states that the MNSPD115 "is designed for both AC and DC systems and provides protection to service panels, load centers or where the SPD is directly connected to the electronic device requiring protection." But service panels and load centers seldom if ever carry AC at less than 90VAC, the nominal rating of the MNSPD115. Please clarify all of this! Thanks, Allan   On 8/13/2013 11:28 AM, Ryan wrote: Allan That is not expected behavior. Which model of SPD are you using? Ryan On 8/13/2013 1:08 PM, Allan Sindelar wrote: Wrenches, Very seldom do inverters in off grid systems ever go to sleep anymore, given the increase in phantom electronic loads and greater customer expectations. Coupled with lower module prices, we usually size larger arrays and inverters remain on continuously. However, we also service and upgrade many existing systems, and some customers still want their inverters to go into search mode. They typically either have gotten used to a more energy frugal lifestyle over many years, or (to their credit) choose to buck the system and live with a lighter energy and resource footprint. Twice in recent months we have added Midnite MNSPD MV surge arrestors to the AC output of smaller systems and discovered that the inverters will no longer go into search mode. It doesn't appear to make any difference where the search watts threshhold is set. One system used a 24V Outback FX2524T (with current boards following a nearby lightning strike) and the other used a Magnum MS2812. In the former case, we defeated the search (against the customer's preference, as she liked the total silence once her day was done). In the latter, the customer rejected and we removed the surge arrestor once it became clear that the inverter wouldn't sleep. Has anyone else experienced this? Is there a fix for it? Robin, can you chime in here (off list if necessary; I'll carefully post your response)? Thank you, Allan -- Allan Sindelar al...@positiveenergysolar.com NABCEP Certified PV Installation Professional NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder and Chief Technology Officer Positive Energy, Inc., a Certified B CorporationTM 3209 Richards Lane Santa Fe, New Mexico 87507 505 424-1112 office 780-2738 cell www.positiveenergysolar.com

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