Is it better to have microinverters at 120V or 240V?

[miogpsrocks]

Is it better to have microinverters at 120V or 240V?

I am in the US and most stuff runs on 120V except the big stuff like a AC, dryer or water heater.

Thanks.

[Will792]

As far as I know all residential microinverters for US market work for 240V. Service in the US is split phase 240V with neutral set to ground. This means that micro-inverters would feed electricity to house 120V devices on both legs.

[miogpsrocks]

As far as I know all residential microinverters for US market work for 240V. Service in the US is split phase 240V with neutral set to ground. This means that micro-inverters would feed electricity to house 120V devices on both legs.

To plug into the normal AC outlet, you need 120V not 240V right? It will just power the leg it happens to be plugged into. Do both legs have to be powered equally or what if one leg gets all the power from the solar while the other one gets none?

Thanks.

[sdold]

Grid tie inverters in the US don't plug into a receptacle, they usually connect to the service panel, 240V through a two-pole breaker. One reason "plug in" types aren't used or allowed is that they can add current to a branch circuit that bypasses the protection of the circuit breaker. If I had a shack in the desert that my family didn't live in, I might consider it, but not with a normal house and a family to protect.

[miogpsrocks]

Grid tie inverters in the US don't plug into a receptacle, they usually connect to the service panel, 240V through a two-pole breaker. One reason "plug in" types aren't used or allowed is that they can add current to a branch circuit that bypasses the protection of the circuit breaker. If I had a shack in the desert that my family didn't live in, I might consider it, but not with a normal house and a family to protect.

All of the grid tie Inverters that I have are 120V and just plugin or have the ability to plugin a normal socket. I either got them on ebay or Aliexpress.

How does it bypass the circuit breaker? The plug connects to one of the switches on the circuit breaker panel. Are those circuit breakers only 1 way? If I draw too much power from one of those outside plugs, it will trigger the circuit breaker and shut off.

Also, you are saying they are not allowed and that they are dangerous? Is there a law against it? My family insist that dealing with anything higher than 120V is dangerous and that these are the safer option.

How are you suppose to get those fancy style ones connected? Using some kind of electric busbar which feeds the various other power boxes?

https://youtu.be/ut6LA5faRmI

Thanks.

[SunEagle]

I would not use one of those 120v plug in inverters. They have been labeled illegal in the US due to they can cause a house fire which can void your home insurance.

[sdold]

All of the grid tie Inverters that I have are 120V and just plugin or have the ability to plugin a normal socket. I either got them on ebay or Aliexpress.

It's not illegal to sell those, own them, etc. The problem is the safety aspect that I mentioned, and also that they don't meet the requirements of virtually all of the local building authorities, at least in the US. I'm not down with getting a building permit for every little thing like adding a branch circuit, new kitchen cabinets, stuff like that. But I'm not screwing with some cheap Chinese thing that has a real potential to start a fire and invalidate my fire insurance, or get me into hot water with the PoCo when they notice that I'm backfeeding without a permit (which insures you aren't using this junk)..

How does it bypass the circuit breaker? The plug connects to one of the switches on the circuit breaker panel. Are those circuit breakers only 1 way? If I draw too much power from one of those outside plugs, it will trigger the circuit breaker and shut off.

By adding current downstream of a circuit breaker, you allow the branch circuit to carry more current than it's rated for without tripping the breaker. This could happen, for example, if two 1200W heaters were plugged into the same 15A branch circuit. That would trip a 15A breaker, preventing the wire from carrying 20A. But if your solar inverter is putting out 6A, the branch circuit is still drawing 20A, but 6A is from the solar inverter and 13A is from the breaker. The wire is carrying 20A, but the breaker never trips.

Also, you are saying they are not allowed and that they are dangerous?

Not allowed by most, if not all building safety jurisdictions in the US, and yes, they can be dangerous under the right conditions as described above.

Is there a law against it?

It's that they violate most local building codes and can invalidate your fire insurance

My family insist that dealing with anything higher than 120V is dangerous and that these are the safer option.

That's incorrect and comes from a lack of knowledge of electricity. A harmless static shock is thousands of volts, and an arc welder that joins steel together is around 20 volts.

How are you suppose to get those fancy style ones connected? Using some kind of electric busbar which feeds the various other power boxes?

They normally connect to a two-pole breaker in the service panel. The breaker looks like a typical 240V breaker for a dryer or hot tub, but will be labeled "Solar" and is actually feeding current into the panel, not out of it.

Like I said, I'm not a stickler for codes, but this is one area where I wouldn't risk my family's home. To me it would be like putting in a cheap Aliexpress wood stove without a ceiling box for the pipe because "I'm only going to burn small fires, and who will know?"

[Will792]

In addition to what people mentioned above about building codes it is also illegal to connect any electricity generator to home electric system with grid electric service, without a method that guarantees grid disconnect when generator is connected. Personally I would not use these Chinese 120V inverters at all but the most acceptable, risk wise, option is to use them in standalone mode, connecting to one device only.

BTW most utility companies have a written rule that says that they can disconnect your supply line if the see grid feeding generator.

not trying to scare you but it can easily start electric fire in the house that won’t even be covered by insurance.