For sure, if it is a mission-critical situation where service can't be provided in a timely fashion, the customer should be able to bypass things. We do that for clients where we have to take a boat to provide service, for example.
In the case of an Enphase whole-home battery backup, most around here are designed for "whole home," but with an adjusted lifestyle. So when the MID fails, living a normal lifestyle often means depleting the batteries, so it requires a timely response to avoid a lifestyle change. For example, shutting down a swimming pool is usually necessary, and possibly water heating. In some cases, that also means shutting down one of two central air conditioners. On the other hand, I had a client whose MID froze open, and they didn't realize it for almost a month. They ran off-grid on solar and batteries without a care in the world. Unfortunately, the fix was a real hassle because the Enphase System Controller contained the service disconnect, making service difficult and temporary bypass impossible. For this reason, I have stopped using MIDs (Enphase System Controller or Tesla Gateway 3) as the service equipment. I don't think that is in the customer's best interest, especially in states where you have to involve the utility company and the building department to pull a meter for service. Adding a 200A service disconnect ahead of the MID is pretty low cost. It will also make things easier in 15-25 years when the MID gets replaced with the latest and greatest tech. Jason Szumlanski Principal Solar Designer | Florida Solar Design Group NABCEP Certified Solar Professional (PVIP) Florida State Certified Solar Contractor CVC56956 Florida Certified Electrical Contractor EC13013208 On Wed, Oct 15, 2025 at 4:42 PM Dave Tedeyan <[email protected]> wrote: > Jason, > > While I agree that it is often fairly simple to bypass an inverter, you > have to be there to do it. I am currently dealing with a Midnite system > that has needed multiple firmware upgrades, and for some reason recently > would not charge the batteries. No one noticed until they completely > discharged, and the backed up loads turned off. We have been able to get > them charging again, but it has been really nice to tell the customer to > just throw the transfer switch and let the loads run off the grid while > this gets sorted out. Tech support has been very helpful, and we've got the > batteries charging again, and I am really glad I did not have to make an > emergency trip to the site to temporarily wire the AC in to the AC out. > > AC coupled systems with an MID seem to be a little more resilient in this > fashion though. For that Enphase customer to lose power to the loads, both > the System Controller AND the batteries would have to fail at the same > time. I recently ran into an Avalon SEP that failed. We were able to get it > to still pass through grid power and even get both the AC and DC coupled > solar working immediately. Then at my leisure I was able to go to the site > to troubleshoot (and eventually replace) the SEP. They just did not have > backup power during that time, but at least they had power to the house. > > Cheers, > Dave > > On Wed, Oct 15, 2025 at 2:50 PM Jason Szumlanski via RE-wrenches < > [email protected]> wrote: > >> I think there’s a real point of diminishing returns here. Even on >> whole-home backup systems, I usually skip a dedicated bypass as long as >> there’s a reasonable way to restore power in a true emergency. >> >> For *off-grid*, it’s definitely convenient to send generator power to >> the loads during inverter service. But if the generator feed is spliced to >> feed both the inverter and one side of a bypass switch, you still have to >> disconnect the inverter feed to make it safe for service, so the benefit >> can be marginal. The real benefit here is for clients to be able to >> self-service to restore power during a component failure. >> >> For *on-grid* systems, I recently dealt with an Enphase System >> Controller failure. There was a separate main disconnect ahead of it (no >> main breaker in the controller), and the load lugs fed the whole house. The >> controller failed with the microgrid interconnect contactor stuck open, >> forcing the client off-grid even though utility power was available. >> >> Bypassing it took nothing more than a pair of 3/0 Polaris taps and about >> ten minutes to splice the line to the load. Would a 200 A bypass switch >> have been worth it? Not really. The quick splice worked fine, and once >> Enphase sent a field tech to replace the MID, I just reversed it – no big >> deal. >> >> Back to off-grid, or on-grid for that matter... This is where a >> well-planned wiring trough shines. You can make quick splices to bypass >> smart loads or even whole-house feeders when needed. On a recent grid-tied >> multi-Midnite AIO installation, I made sure the AC in and AC out power >> distribution blocks were close enough together that I could completely >> bypass the inverters with some quick Polaris tap splices. Or, I could >> quickly remove and cap off a single inverter from the distribution blocks. >> That's even better than a bypass because you can selectively bypass a >> single inverter for service. >> >> Most bypass switches will live their entire lives never being used, so I >> tend to design for practical flexibility rather than theoretical >> perfection. There are definitely situations where a bypass switch is >> mandatory, in my opinion, but when there are options and the risk is low, I >> often save the customer a few bucks after having a conversation with them >> about convenience, cost, reliability/resilience, and serviceability. >> >> Jason Szumlanski >> Principal Solar Designer | Florida Solar Design Group >> NABCEP Certified Solar Professional (PVIP) >> Florida State Certified Solar Contractor CVC56956 >> Florida Certified Electrical Contractor EC13013208 >> >> >> On Wed, Oct 15, 2025 at 11:26 AM Dave Tedeyan via RE-wrenches < >> [email protected]> wrote: >> >>> Hi All, >>> >>> Now that some inverters have "smart" load capabilities, I am musing on >>> whether to put in a separate bypass for each smart load. I am thinking >>> specifically about the Midnite AIO inverter, where the Smart loads are >>> powered directly from the inverter, rather than just providing a relay to >>> cut power (like in the Avalon SEP, if anyone has used those). The Midnite >>> AIO also has provisions to run other backed up loads directly from the >>> inverter as well. >>> >>> But if there was a system failure, and you have a bypass switch >>> installed, this will only power the loads in the backed up loads panel from >>> the grid, but not the specific loads that originate from the inverter. Are >>> people installing bypasses for every individual load that originates in the >>> inverter? I was just looking at William's interlock system, but I don't >>> think that you can utilize that kind of system to have some smart loads in >>> there as well. It seems like you can utilize the panel he labels "inverter >>> feed" on his one line diagram to power other backed up loads, but the would >>> not work for a smart load. >>> >>> Cheers, >>> Dave >>> -- >>> >>> [image: Logo] <https://www.sungineersolar.com/> >>> Dave Tedeyan, P.E. >>> Owner | Sungineer Solar >>> p: he | him | his >>> a: 1653 Slaterville Rd. | Ithaca, NY 14850 >>> w: www.sungineersolar.com <http://www.sungineersolar.com/> >>> c: (607) 270-0370 >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> >>> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. 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