Does MN15-12KW-AIO have a 200a transfer switch?

[TeslaJerk]

Hi there,

I'm looking at installing MN15-12KW-AIO with 28kwh batteries and 12kw solar to backup my whole house. I have single 200a main breaker panel that has all my loads on it. The wires from the meter should be #4 awg but I'm not positive on that.

Does MN15-12KW-AIO work as a transfer switch with the 200a panel so it prevents the inverter from sending energy to the grid when the grid is down? I'm a notice so I'm not sure what information you need from my end to help me determine if it will work.

Thanks

[Wizbandit]

The MN-ONE can not be connected directly to an electric company meter.  Equipment connected to a service meter are required to have a listing with UL or ETL or some other "Listing" service to be marked "Suitable as Service Equipment".  The MN-ONE AIO does not have this listing so can not be connect directly to a power meter on the grid. You will need to install a 100 Amp circuit breaker in your main breaker box and the MN-ONE inverter system is installed as just an appliance powered from your main breaker box like a Hot Water Heater or Electric Stove.

You then install a 100 amp "Critical Load panel" next to it and move over circuits you want to power during a power outage.  There is a 99% chance the MN-ONE will not power a whole house on a 200 amp load panel.

There are "Controlled Load Outputs" that you can connect bigger loads to such as an electric water heater which the MN-ONE can power IF there is unused power available.  You could connect the 50A controlled load to another breaker box where up to 50 amps max total available loads could be moved over from the main breaker box.

All grid-tie certified inverters have protections against sending power back to the grid during a power outage. Anyone installing this Inverter should use a licenced electric company electrician.

I might mention you can not "SELL" back with this Inverter connected to a 100A breaker in a 200A main breaker box.  The 200A panel box is limited to 40A breaker for "selling".  To SELL and be up to "Code" requires a service tap with an auxiliary 100 amp disconnect with fuses.  The buss bar in the 200A main breaker box may get hot and melt and/or catch fire.  You are allowed by code 20% of the buss bar rating (200A) selling so 20% of 200 amps is 40 amps.

[TeslaJerk]

I did some research from your suggestions. I decided I don't need an automatic 200a transfer switch. If the grid goes down I don't mind manually disconnecting the grid and running off the battery. I might have to do this once or twice a year. Vast majority of the time I want to try to avoid using the grid as much as possible, use the batteries to get me through the night, and export to the grid as much as possible especially from 3p to 9pm. I also don't want to run a critical loads manual or install a manual transfer switch (those things are expensive).

I came across this guy's video and he added a supply side tap and connected to the inverter's grid slot. The load side on the inverter is connected to a 70a breaker on the main panel. He basically has a loop that the energy can flow. He uses an interlock with the main breaker and the load breaker so he can't turn on both at the same time to prevent the loop. I modified an existing diagram with the changes.

Would this setup be code compliant and work with MN15-12KW-AIO?

[Robin]

Sorry, I did not study your diagram. We have a document up on the MidNite website now that talks about the pro's and con's of a 200 amp inverter transfer switch and such. I suggest you read it. Things are not as simple as people want them to be.

[225lakesidedrse@gmail.com]

Hi folks,  interesting thread.  I'm at a similar step in planning, similar question. 

@robin, would you please share the link to the document?

I'm finding the breaker approach above is considered a more risky design.  Another design pattern I'm landing on is the "feeder tap".  See diagram from Eg4. 

Would love to see a #midnightsolar version of this. Maybe a webinar?

*note: I have a 100amp service.

https://drive.google.com/file/d/18LHbrLyCfpDThDW1F6m1FLntpmjJg4Gm/view?usp=drivesdk

[adelay]

@robin, would you please share the link to the document?

https://www.midnitesolar.com/pdfs/200_amp_inverter_thoughts_(2).pdf

[jahyde]

Just in case someone was wondering about a comment above about not meeting requirements to be grid-tied:
https://www.midnitesolar.com/pdfs/MNS_ESS_UL.pdf

In regards to Robin's article, with a 100amp limitation, it would not meet the needs to pass through a 200 amp service, the article mentions people needing 45kw of batteries to support "whole home storage". I hope to service my entire home in a grid failure situation, which in my area extended outages can last 3-4 weeks, so it was not a lot to purchase 60kw of batteries. This scenario might need 2 MN15 inverters just to meet the circuit limits, but my general peak usage stays under 65amps, even with predominantly electric appliances such as water heaters, HVAC, dryers, wells, etc. More awareness is needed as far as SOC, time of day, and solar input, but running the dryer at 2pm on a sunny day would be thoughtless, while running it at 9pm on a cloudy day may need awareness. The MN15 comes so close to supporting 200 amp service, hopefully one day soon this standpoint will be re-addressed. Recent changes like Sodium Ion storage might change how common it will be for a home to have a larger storage system - not just affordably, but also safely raising the KWH bar.