One 120V grid tie inverter on 240V split phase system?

[eccerr0r]

First off I'm not sure if the 120VAC grid tie inverters are all NEC/UL certified.

That being said, what happens if you use one of these if you do have split phase 240V like most of NA, and only have one inverter on one of the two phases?

I can only think of weird stuff happening, none of it is good, so what about those off the boat 120VAC GTI's?

[goontron]

Re: One 120V grid tie inverter on 240V split phase system?

If you do not sync the inverters output waveform to the incoming mains it will sink a metric shitton of power and result in smoke

[eccerr0r]

Re: One 120V grid tie inverter on 240V split phase system?

Sync is not going to be a problem - that's what GTI's were designed to deal with. I specifically wonder about half a split phase operation which is undefined for me...

[stj]

Re: One 120V grid tie inverter on 240V split phase system?

well your power meter wont be happy!!!

[eccerr0r]

Re: One 120V grid tie inverter on 240V split phase system?

I have one of those big brother power meters that theoretically support 240V GTIs and actually has two arrows - one to each possible pointing direction that power can flow.

But who cares what the power meter says as long as it's less than what it would normally would have measured, I generated my own power, the grid doesn't have to supply me as much power!

So nobody tried yet? Someone has to have tried...or perhaps I'm overthinking the possible issues?

I never liked the middle tied neutral thing... gives me the jeevies thinking about current imbalances, which is exasperated by a half phase GTI -- though is it any worse than unplugging everything on that phase...

(Then the other question is: which is better, two half phase GTIs on each phase, or one big 240V GTI that drives only the two phases and ignores neutral...?)

[sam_sam_sam]

Re: One 120V grid tie inverter on 240V split phase system?

(Then the other question is: GTI that drives only the two phases and ignores neutral...?)

I could think about a lot of items that would not be happy about this if the phasing is not right and would you electrical feed be unbalanced in that situation

But a better question is why would want to do this way

I agree with you that I would not want to use a single 240 volt unit but I would go with two 120 volt unit instead

Because would a 240 volt unit work if one phase has more of a load on it than the other and does the 240 volt unit have a neutral wire on it

[eccerr0r]

Re: One 120V grid tie inverter on 240V split phase system?

I could think about a lot of items that would not be happy about this

But effectively the power company is doing exactly this to you when you get one phase 240V - they don't ship neutral to you...

However for a GTI there probably should be a "neutral" point of sorts...well, at least if you implement it a certain way...

[sam_sam_sam]

Re: One 120V grid tie inverter on 240V split phase system?

But effectively the power company is doing exactly this to you when you get one phase 240V - they don't ship neutral to you...

You are right to a point in that the neutral is more or less an earth ground at utilitie the pole for 120 volts on each side

[eccerr0r]

Re: One 120V grid tie inverter on 240V split phase system?

So if you have a 240V GTI, that's got no ground reference in the circuit other than the case that's isolated from the 240V, where do one connect the GND?

[eccerr0r]

Re: One 120V grid tie inverter on 240V split phase system?

Yes the whole intent of having half split phase GTI is purely cost, especially if the intent was not to sell back but rather compensate ones own use on that particular leg.

But now... after thinking about this some more, the neutral tie is key.

if the neutral tie is perfect, a half split phase GTI should actually work and nobody would know the difference. Mostly.

However if the neutral tie is compromised, all of the problems I've thought about become real issues, among a whole slew of other problems that would show up even without a GTI.