208 system in Mexico

[solar baked]

Hello all,

I would like to build a hybrid system at my property in Mexico, but I am a little confused on how to go about it and am hoping someone on here knows how to do this.

I have 3 phase power at my panel. However, there are only two of the three phases on my service, so looking at the panel, it looks like a typical single, split phase system. This is a typical installation in my area of Mexico. So I have L1, L2, and neutral. Each leg to neutral is 120v, and leg to leg is 208v (in reality 201v).

My question is this: How do I handle a hybrid inverter system? My thought is that I need two 120v inverters. Is there software on the inverter that correctly balances the two legs so that the input/output to/from the grid is 120 degrees out of phase? If so which inverters are capable of this.

 

[Rocketman]

There are several inverters that will handle it.

Get two Victron Multiplus II 48/5000’s and set the up in split phase.

Also, many AIO’s (All in Ones) handle split phase.( I can’t help much here, because I don’t know that much - but they are usually cheaper).

A lot depends on your goals for the system.

Can you economically back feed the grid (sell the grid your excess power)?

Are you looking at going all off grid?

Reducing your power bill?

Run both solar and grid at the same time?

Are you wanting a battery?

How much power are your loads?

Do you have room for a large solar array?

Good Luck

 

[hwy17]

My question is this: How do I handle a hybrid inverter system? My thought is that I need two 120v inverters. Is there software on the inverter that correctly balances the two legs so that the input/output to/from the grid is 120 degrees out of phase? If so which inverters are capable of this.

You don't have to operate 120 out of phase. It is a technical reality at the transformer that you are 120 out of phase, but as far as your sine wave is concerned it looks like a pure 180.

You just need to use an inverter that is capable of 120/208v single phase operation.

 

[Hedges]

Inverter configured for split-phase won't do it.

My Sunny Island will, configured for 3-phase.
You could install 2 (or 3) of these 120V inverters. If L1 and L2 are there, Master and Slave1 will sync to them and pass through. Because you don't have L3, even if you have inverter Slave2 it won't connect but will continue to make a 3rd phase (of 120V, won't track the input voltage of L1 & L2.)

Sunny Island can be configured to shut off all inverters if 3rd phase fails, or continue operating.
It can also create split-phase given just 120V input.

Whatever 3-phase or stackable single phase inverter you get, needs to work without L3 being available on input.

That's for the hybrid or battery inverter.
Some GT PV inverters support 208V as well as 240V (and some 277V as well). Without driving current into N, may just monitor it to auto-configure voltage.
For my Sunny Island (battery inverter) I use GT PV to solar panels.

Possibly Victron, Schneider, SolArk, others will do similar. You may have to inquire if they work with L3 missing, unless someone here has experience with them.

 

[hwy17]

I don't think you have to put them in 3 phase mode with a leg "missing". It looks like Sol Ark, 18kPV, and others have a dedicated 120/208 single phase mode.

 

[fromport]

Inverter configured for split-phase won't do it.

Luxpower/eg418kpv can do 120/208 split phase, so connect 2 out of 3 phases for sure as well

 

[mapsofilti]

A side note; something cool about having the neutral in a three wire 208Y/120 or 220Y/127 V service is that you can derive a system with the missing phase to properly drive three phase equipment if you ever need to. I.e. by using an open-wye open-delta transformer setup:

or

 

[solar baked]

Thanks for all the replies. There is a lot to consider here.

 

[Hedges]

A side note; something cool about having the neutral in a three wire 208Y/120 or 220Y/127 V service is that you can derive a system with the missing phase to properly drive three phase equipment if you ever need to. I.e. by using an open-wye open-delta transformer setup:

View attachment 197796 or View attachment 197798

Works in theory! Practice? That's something else.

(with apologies to @svetz )

My experience has been that the "regulation" of transformers leads to the derived leg isn't quite correct voltage/phase. Feeding an E-core transformer or motor, could result in a bit of excessive current.

I was using that to get a 3-phase Sunny Island to take both L1 and L2 of 120/240V split-phase as input, rather than just 120V single phase. It did connect, but then drew 20A for a while probably fighting offset before disconnecting.

 

[solar baked]

There are several inverters that will handle it.

Get two Victron Multiplus II 48/5000’s and set the up in split phase.

Also, many AIO’s (All in Ones) handle split phase.( I can’t help much here, because I don’t know that much - but they are usually cheaper).

A lot depends on your goals for the system.

Can you economically back feed the grid (sell the grid your excess power)?

Are you looking at going all off grid?

Reducing your power bill?

Run both solar and grid at the same time?

Are you wanting a battery?

How much power are your loads?

Do you have room for a large solar array?

Good Luck

I'm want to be able to tie to the grid, export to the grid, use solar when the grid is down, and have battery storage to pull off of at night and when the grid is down. I would like an inverter with auto-transfer switch. I have room for a fairly large array probably 24 large panels or maybe more. I haven't added up the loads yet, but want to be able to run 2 small mini-splits, 400w pump, fridge, etc. Because of the climate, I don't need much heat or ac (currently have none). The dryer and stove are gas.

 

[solar baked]

You don't have to operate 120 out of phase. It is a technical reality at the transformer that you are 120 out of phase, but as far as your sine wave is concerned it looks like a pure 180.

You just need to use an inverter that is capable of 120/208v single phase operation.

So then I could do it with one single, split phase inverter as long is it could be programmed to 120/208v?

 

[Supervstech]

You don't have to operate 120 out of phase. It is a technical reality at the transformer that you are 120 out of phase, but as far as your sine wave is concerned it looks like a pure 180.

You just need to use an inverter that is capable of 120/208v single phase operation.

Yeah, when pairing inverters on a 208 volt system, they have to be set to 120degree operation, or you will get 240V…

 

[Supervstech]

So then I could do it with one single, split phase inverter as long is it could be programmed to 120/208v?

Yup, and the programming alters the pwm to a 120degree link.

 

[solar baked]

It looks like one EG4 18kPV-12LV will do it. I think I am just over-thinking the problem.

 

[Hedges]

I'm want to be able to tie to the grid, export to the grid, use solar when the grid is down, and have battery storage to pull off of at night and when the grid is down.

So then I could do it with one single, split phase inverter as long is it could be programmed to 120/208v?

Be sure to select based on capability and quality first.
Any motor loads to start? What ambient temperatures must it operate in/

Me, since I like SMA, would buy a pair of Sunny Island in a box, $4000 from an eBay seller.
You plan to backfeed the grid? What functions are required (latest UL 1741-SB? Or just original UL-1741?)
I favor new old stock if latest grid support functions aren't required. Latest model if that is required for grid-tie in your location.

It looks like one EG4 18kPV-12LV will do it. I think I am just over-thinking the problem.

That plus suitable number of PowerPro may do everything you need.

SolArk for better support.

SMA or Schneider for tier-1 hardware, aging firmware, little support. Most robust ability to power heavy loads.

Also check out Midnight. Inverters are new offerings, but the designers are pioneers of the industry, and the equipment should perform very well. They are demonstrating massive surge capability. Ask them if they support 2 legs of 120/208.

 

[solar baked]

You plan to backfeed the grid?

yes

 

[solar baked]

Any motor loads to start? What ambient temperatures must it operate in/

Right now I just have one 1/2hp pump feeding my water pressure system, but would like some spare capacity built in.

The temperature ranges between 40 degrees to 90 degrees, seldomly. Generally the temp ranges from 50 at night to 80 in the day all 12 months.

 

[Hedges]

yes

What are the requirements?

I picked up a nice Sunny TriPower 30000TL-US for a song. It supports UL-1741-SA.
PG&E rejected it because there are additional requirements since mid 2020.
The inverter was listed on CEC website and checked all the boxes shown in the chart from HTML.
But downloading Excel spreadsheet, there were additional columns with grid-support functions it lacked.

Depending on your utility's requirements, you may need a recent model like Sunny Boy -41 (or similar from other brands.) Or, an old model no longer allowed in many US markets might be allowed and could be had for cheap.

There have been Sunny Boy 10000TL-US-10 inverters (208V only) offered as new old stock.

But your first order of business is finding the right battery or hybrid inverter.

Right now I just have one 1/2hp pump feeding my water pressure system, but would like some spare capacity built in.

Look at label for "LRA", otherwise assume 5x running current. It is probably around 3500VA required to start that motor.

The temperature ranges between 40 degrees to 90 degrees, seldomly. Generally the temp ranges from 50 at night to 80 in the day all 12 months.

Pretty mild. The cheap brands should be OK at those temperatures (but still may not have the same 20 year or so lifespan of Tier-1.)

How about humidity? Corrosive elements like salt air, or ammonia from livestock?

 

[solar baked]

How about humidity? Corrosive elements like salt air, or ammonia from livestock?

Its mostly pretty dry with no corrosive elements. Equipment will be under a covered carport.

 

[Hedges]

Should be OK for any brands.

Better quality has conformal coat on PCB, some have sealed enclosures.

Do you have time of use rates, where you will want to charge batteries off-peak and use battery rather than drawing from grid on-peak? In California, time of use is optional for normal customers, but any with PV net metering is required to be on time of use.

All sorts of features to consider.

And then price varies 5:1 between brands. Performance varies too. And bugs/issues.
Have to do what is affordable to you, but Google and search this site for the models you consider so you go in with eyes wide open.