is it possible? adjust volt with transformers

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
.. because 220v inverter are more common on the market, versus US format!... and toroidal transformer, aren't expensive ! ( I know we will have some lost of power... )
 

Attachments

  • posible2.jpg
    posible2.jpg
    49.4 KB · Views: 7

A.Justice

Swears he didn't start that fire.
Joined
Sep 12, 2020
Messages
1,090
Location
TN
I'm pretty sure the European 240 volt inverters use 3 phase, or at least more phases than we use in the US (I'm not super familiar with 240v European power). A lot of the 240 volt units are 50 hertz as well, and if the it's the 60 Hertz model, it's for the "US", and they generally cost just as much as the 120v US units.

I had actually looked into doing the same thing, buying a cheaper inverter designed for European use, and converting the voltage into something more usable. Between the losses of conversion, issues with phasing, and cost of additional components, I decided against it, and just went with a 120 volt 60 hertz US model.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
I'm pretty sure the European 240 volt inverters use 3 phase, or at least more phases than we use in the US (I'm not super familiar with 240v European power). A lot of the 240 volt units are 50 hertz as well, and if the it's the 60 Hertz model, it's for the "US", and they generally cost just as much as the 120v US units.

I had actually looked into doing the same thing, buying a cheaper inverter designed for European use, and converting the voltage into something more usable. Between the losses of conversion, issues with phasing, and cost of additional components, I decided against it, and just went with a 120 volt 60 hertz US model.
nope EU have single phase 220V too!.. and those are auto sense 50 or 60hz, by the way they use it to control the synchronization!......... 90 to 95 percent efficient( of these toroidal).....supose 90% and you are generate 2Kw, your lost could be 200Watts!!!!!!... No to bad!, and you will save close to 50% ( because the toriadal on alibaba are cheap too! ).. I'm looking if some one , try!
 

efficientPV

Solar Addict
Joined
Sep 24, 2019
Messages
602
Funny they won't show you the transformer, that should be pretty dinky and only a KW at best. Now try and buy those connectors.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
Funny they won't show you the transformer, that should be pretty dinky and only a KW at best. Now try and buy those connectors.
https://www.alibaba.com/product-det...60760420309.html?spm=a2700.9114905.0.0.ex0tLJ
 

Ampster

Renewable Energy Hobbyist
Joined
May 3, 2020
Messages
5,186
Location
Kenwood, California
because 220v inverter are more common on the market, versus US format!... and toroidal transformer, aren't expensive !
Of course there is a cost of violating the KISS principle. Adding complexity when there are less complex alternatives has to be evaluated economically. It is a global marketplace and I have not seen hard data that equipment built to North American standards is actually any more expensive than similar European equipment. If the difference is between UL rated and non UL rated equipment, I understand the difference in price.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
Of course there is a cost of violating the KISS principle. Adding complexity when there are less complex alternatives has to be evaluated economically. It is a global marketplace and I have not seen hard data that equipment built to North American standards is actually any more expensive than similar European equipment. If the difference is between UL rated and non UL rated equipment, I understand the difference in price.
example....https://www.alibaba.com/product-detail/AC-Inverter-5KW-8KW-Single-Phase_1600246655876.html?spm=a2700.12243863.0.0.20683e5fPMUpd2 it will be the perfect option, or deye..... but solark have esclusivity of them and sell those here in USA at $7K. when do you ask to the supplier, they say... no stock, those are exclusivity of solark!.............................."Adding complexity" of course will be some, but are only 4 more passive connections! by phase! and have another benefit, if you put the transformer close to the meter, you could delivery more power using the same cable, close to 2 time! another more..... you will need 2 inverter..... it multiply the Mppt, and divide the battery (less AH in one connection) and there 2 inverter, 1 fail, but you will get power yet! ... plus the toroid I saw, has only 2 or 3% of lost!
 
Last edited:

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
Those are the differences between UL rated and non UL rated inverters not USA voltage versus European/Asia voltage.
of course, but.. we are two different customers, 1 the goals is low the bill ( 0 export) 2. Low the bill and make some money exporting energy!!!....... I thing that is a waste of money, simple example..... they sell to you 1kw at 29c, but they pay to you 1Kw at 9c...................... My goal: put all appliance to electric in my house, bolila/air-conditioner....( heat pump) ...... and if i can supplier mostly al my watts! will be great!..... and better businesses!.. I think so!.... they way to maxim power, 1. no expend so much money, but no sacrifice the quality 2. use solar track( my self) to can get 40% more of energy
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
10,609
Difference between 220V and 240V is small enough most appliances will run on either. Even on 208V. Motors draw a bit more current. Heating appliances operated at a bit lower wattage.

You can make up the difference with a buck-boost transformer. That is an auto-transformer rather than isolation transformer, magnetically producing the extra 20V or 32V in secondary winding which is connected in series with primary. It's efficiency loss is only applied to that percentage of the power; the 208V or 220V out of 240V is used without going through magnetic coupling.

Bigger difference between European 220V single-phase and U.S. 120/240V split-phase is in the U.S. we have two hots, L1 & L2. For grid-tied systems we need a 2-pole isolator. You can't just use the SPST relay built into a 220V inverter to disconnect a 120/240V system from the grid.

They may be OK for an off-grid system. Although, for a transformerless inverter I would worry about battery voltage possibly having 120VAC superimposed on it, making it a safety hazard. That would depend on whether it has galvanically isolated HV section (which can be done with small high-frequency transformer.)

If you use a 120/240V auto transformer on output of the inverter, with center-tap grounded, the SPST relay would only isolate one utility leg. Your inverter would try to backfeed the other leg to grid.

If you used a 240V (or 220V) primary, 120/240V center-tapped isolated secondary, that might work. I would still have concerns about one leg of the primary remaining connected to utility grid; I don't think it should be used that way. A 120V single-phase inverter (like one of my US model Sunny Islands) would be OK; one wire goes to neutral, the other through SPST relay to hot.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
example of waste of money, solark, are a OEM inverter, but solark bought the exclusivity of distribution, and grow up the price of 1350 to 7000!.... it is a scam!.....the bad is only 1 of 5 they espect to go to these bussines, are quit, because the hight cost, an they begining to have a big finacila problem, because pay for exlusivity! are so danger!!!!.. many firms broke yeas ago, for do it!!!!
Difference between 220V and 240V is small enough most appliances will run on either. Even on 208V. Motors draw a bit more current. Heating appliances operated at a bit lower wattage.

You can make up the difference with a buck-boost transformer. That is an auto-transformer rather than isolation transformer, magnetically producing the extra 20V or 32V in secondary winding which is connected in series with primary. It's efficiency loss is only applied to that percentage of the power; the 208V or 220V out of 240V is used without going through magnetic coupling.

Bigger difference between European 220V single-phase and U.S. 120/240V split-phase is in the U.S. we have two hots, L1 & L2. For grid-tied systems we need a 2-pole isolator. You can't just use the SPST relay built into a 220V inverter to disconnect a 120/240V system from the grid.

They may be OK for an off-grid system. Although, for a transformerless inverter I would worry about battery voltage possibly having 120VAC superimposed on it, making it a safety hazard. That would depend on whether it has galvanically isolated HV section (which can be done with small high-frequency transformer.)

If you use a 120/240V auto transformer on output of the inverter, with center-tap grounded, the SPST relay would only isolate one utility leg. Your inverter would try to backfeed the other leg to grid.

If you used a 240V (or 220V) primary, 120/240V center-tapped isolated secondary, that might work. I would still have concerns about one leg of the primary remaining connected to utility grid; I don't think it should be used that way. A 120V single-phase inverter (like one of my US model Sunny Islands) would be OK; one wire goes to neutral, the other through SPST relay to hot.
total agree, but is different if the inverter, single phase(220-240) go to a autotranformer to delivery-->120v single phase ( more basic impossible)
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
10,609
total agree, but is different if the inverter, single phase(220-240) go to a autotranformer to delivery-->120v single phase ( more basic impossible)

So long as you have 220V or 240V single-phase (Line and Neutral) to feed it.
That wouldn't be found in U.S. residential, but some commercial installations.

What you can do is use an isolation transformer to make 220V single phase from 240V split-phase or 120V single-phase utility feed. I think either of those can be either isolation or auto-transformer. Plus of course another transformer on inverter output, if you want single or split phase.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
example of waste of money, solark, are a OEM inverter, but solark bought the exclusivity of distribution, and grow up the price of 1350 to 7000!.... it is a scam!.....the bad is only 1 of 5 they espect to go to these bussines, are quit, because the hight cost, an they begining to have a big finacila problem, because pay for exlusivity! are so danger!!!!.. many firms broke yeas ago, for do it!!!!
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
The single –phase, a two-winding transformer is reconnected as an autotransformer as shown in Fig.2. The current ratings of the windings are given by

autotransformer example

Fig.2: Autotransformer Example
Iab=10,000/110 = 90.9 AIab=10,000/440 = 22.7 A

At full or rated load, the primary and secondary terminal currents are

I2= 90.9 AI1 =I2+I3 =90.9+22.7 = 113.6 A



Therefore, the kVA rating of the autotransformer is

kVA1 =(440)(113.6)/1000 =50 kVAkVA2 =(550)(90.9)/1000 =50 kVA



Note that this transformer, whose rating as an ordinary two-winding transformer is only 10 kVA, is capable of handling 50 kVA as an autotransformer. However, not all of the 50 kVA is transformed by electromagnetic induction. A large part is merely transferred electrically by conduction.

The apparent power transformed by induction is
Sind=V1I3=(440)(22.7)VA=10kVA


The apparent power transformed by conduction is
Scond=V1I2=(440)(90.9)VA=40 kVA
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
10,609
Correct.

But the question is exactly what grid configuration you are going to hook this inverter to, and what you will do on the load side.
My concern is that sneak paths can result in backfeeding the grid when inverter is supposed to be disconnected. I think it can be accomplished, but need to be careful, consider how things are wired when designing.

Initially, Sunny Island was only available in 220V European model, and I considered that.
Later, I bought a single 120V US model. Same 56A SPST relay only carries half the power in this application.
I considered ways to transfer PV between grid and backup.
But eventually, I acquired and installed four Sunny Island, wired 2s2p.
 

adolfo

New Member
Joined
Dec 25, 2020
Messages
33
Correct.

But the question is exactly what grid configuration you are going to hook this inverter to, and what you will do on the load side.
My concern is that sneak paths can result in backfeeding the grid when inverter is supposed to be disconnected. I think it can be accomplished, but need to be careful, consider how things are wired when designing.

Initially, Sunny Island was only available in 220V European model, and I considered that.
Later, I bought a single 120V US model. Same 56A SPST relay only carries half the power in this application.
I considered ways to transfer PV between grid and backup.
But eventually, I acquired and installed four Sunny Island, wired 2s2p.
remember, my goal is 0% export!... and the CT take care of the measure to do it!
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
10,609
remember, my goal is 0% export!... and the CT take care of the measure to do it!

One, I wouldn't trust zero export to be accurate enough to avoid exporting 10's of milliamps, sufficient to be hazardous to human (lineman) safety.
I would want UL-1741 anti-islanding as well.

Two, is this just a grid-tie inverter, which will shut down if grid fails?
Or, is it supposed to disconnect from grid in that case, and continue powering protected loads?
If the latter, that is where you need to be certain it is fully disconnected, not backfeeding because one phase and neutral/ground of centertapped transformer provides a path.

Can you sketch out utility feed, inverter (with its internal relays), transformers, to show how it all works?
That picture would make it possible to see if any situations of powering protected loads will also backfeed the grid (and heavily load down inverter in the process.)
 
Top