Can Two Inverters (One On-Grid, One Off-Grid) Be Connected to One Network?

Hi, can two inverters be connected to one network? One on-grid inverter which feeds the excess to the grid and the other off-grid inverter which has baypas + batteries. Behind the meter, I would first connect On-grid, which releases the excess to the grid, then off-grid, which charges the batteries and has a bypass thanks to which it allows what is produced by On-grid + selected energy from the power plant to pass through. Of course, the inverters would have separate lines with the PV panels.

You can, but why bother?

- Because you can?;
- Because it is easy to connect on-grid 3 phases and off-grid 1 phase in this way;
You could come up with ten more reasons.
Of course, it is better to connect the on-grid inverter after the off-grid inverter, but you need to have AC coupling and compatibility of the number of phases - so either a 3-phase off-grid or a 1-phase on-grid

It is about connecting two 3-phase inverters. That is, creating a hybrid set

Of course you can - the question is how do you want to do it?
First Network -> On-Grid -> Off-Grid - no problem, but if there is no network, On-Grid does not work
or Network->Off-grid->On-Grid, then read about AC Coupling because support for this standard is required to avoid overcharging the batteries, and very few manufacturers offer this

Network -> ON GRID -> Off grid.


On grid sends to the network and forwards to Off grid
Off grid charges the batteries and transfers them to the house


If there is no electricity, it only works off grid and takes power from the battery + panels
So it would be a hybrid

Filipdz wrote:

Network -> ON GRID -> Off grid.


On grid sends to the network and forwards to Off grid
Off grid charges the batteries and transfers them to the house


If there is no electricity, it only works off grid and takes power from the battery + panels
So it would be a hybrid

In the end, the result is the same as a small UPS, e.g. for circulation pumps, with the difference that the UPS does not have additional power supply from the panels.

This all takes care of one off. It's just a matter of setting priorities.

Deals off hybrid. A cheaper option is to buy off the island

And which off-island solution do you recommend in such a connection, i.e. first on-grid and then expansion with off-grid.

I already have a 3-phase on-grid installation from Solis, I am interested in a 4-6kW single-phase off-grid, I will bridge a phase to a 3-phase house, because I think 3-phase ones are expensive and there is a small selection of them.

I am interested in an inverter that will not cause any problems with startup and possible configuration, because I have no experience in this, it would be good if it could be controlled via Wi-Fi. I would like the house to be powered off-grid first, I think it's more economical unless I'm wrong. I am asking for advice from someone who has two such installations at home.....

Take a look at Easun inverters (budget ones):

Manufacturer`s store (CN): https://pl.aliexpress.com/store/1953446
Manufacturer`s store (EU): https://pl.aliexpress.com/store/912469656

You probably won`t be able to handle the entire house load with one inverter, because what you will achieve is a maximum of 8kW on one phase on such iSolar SMW , you need to build parallel solutions, as in the attachment. Attached is a manual for the inverter that sheds more light on such topics.

The second option is a three-phase hybrid inverter - added in parallel to the current installation, e.g. Deye SUN-5K-SG03LP1-EU and appropriate overvoltage of the installation to have a "backup" from the hybrid. Here you will find documentation with examples of how and what is connected.

I`m on the subject myself in the next thread - Double PV installation (on-grid and off-grid hybrid) and Moje Prąd 4.0

Thanks for the advice...

I am not interested in off-grid photovoltaic production that completely covers my daily demand because I have a 4-year-old on-grid set that mostly covers my electricity demand because I produce about 5.5MWh a year and I am missing about 0.5MWh / or even 1.5MWh in the future/ so that after deducting 20% for the electricity supplier, I will break even on the bill (of course I have to pay the subscription fee/).

I would like to invest in photovoltaics, but I do not have the possibility to expand the on-grid installation, so I am interested in off-grid combined with on-grid, and what is more important in this case is that I will not have to report the additional system to the energy industry.

I don’t know how to calculate it, I’m trying to educate myself on this forum, but for now I’m confused, it’s hard for me to understand what the right set would be for me (how many panels, what inverter and, most importantly, what battery capacity) to cover this lack of electricity. Sometimes forum posts are written in difficult language. Maybe there is already an open topic on the forum suitable for me? Thanks for the help...

You can successfully add an island off-grid to the existing on-grid, the only trick is to "pass" the entire load that you want to power from the off-grid through dedicated circuits, while you plug the off-grid inverter itself into the network in essentially the same way as on-grid , although the higher art will be to build the installation so that the batteries can be charged only from on-grid and off-grid PV panels (if you assume such a need).

The installation is then divided into the so-called home-load (high-power devices whose use may overload the phase/inverter) and backup-load (low-power devices or those that you want to keep on batteries in the event of a blackout).

If I were you, I would start with calculator and assessing how much peak energy the devices you want to keep online can consume.

As for batteries - a great video (unfortunately "non-commercial" lead-acid traction or semi-traction batteries were omitted) you can find here on Youtube Do you have some information about the costs? here .

Also remember that the off-grid hybrid inverter can also work as a UPS, charging batteries from the grid, without PV panels ;)

And for a total winter blackout without an auxiliary generator with a starter, e.g. like this it won`t work.

And you can take a look at my thread in the topic in which I am "sewing" such an installation.

Hello,

I have a question.
I have had a 10 kW 3-phase on-grid inverter for 2 years now and it produces about 8.6 kW per year and I am about 4 kW short of my total demand.
I bought a 5 kW hybrid on/off grid inverter for 1 phase. I connected it to separate 5 kW panels. It works nicely as off-grid, but now I would like to make excess electricity to send it to the grid. I did all the installation myself. Can I connect this one phase in the selected phase to the grid? This means there will be no problem with the current inverter? In the summer, I will definitely only have to use this inverter as an off-grid because in the summer the grid is overloaded and the inverter keeps turning off because it is above 253v. Enea reduced the voltage in the transformer in the grid so it is already better, but I am still happy with the output over 8 kW. It’s only known that Enea takes 20%. That’s why I’m wondering if I connect this 1-phase hybrid inverter to which of the phases in the house, will the voltage increase? Definitely yes, only winter in autumn will be ok, probably worse in summer and spring... unless you can bridge 1 phase of the hybrid one and connect this 1 phase to 3 phases separately. Is there such an option?
Has anyone done this before?
Regards

waltergraham72 wrote:

unless you can bridge 1 phase of the hybrid one and connect this 1 phase to 3 phases separately

So what would it look like? Unfortunately, connecting 5kW as 1F is above the standard of 3.68kW.

Probably the off-grid inverter you bought does not have RfC, so you cannot send the energy produced by this inverter to the grid because this is illegal.

Regards

Thank you very much for your quick reply
I know that it can't be 5kW per 1f because it has to be 3.68kW, but let's be honest, a hybrid wave will never achieve such power in autumn or winter. In summer and spring, the washing machine, the pool heat pump and the water pump will be connected directly to this inverter. So that it downloads less from the Internet.
As for the inverter I have, I bought one specially, I asked the manufacturer so that I could send energy to the grid. It is an on grid / off grid inverter. He recommended a model and I bought it. Why is this supposedly illegal? There are protections against the 10 kW meter. The inverter will never send more than 10 kW. If I connect the hybrid inverter in winter-autumn to add something to the grid together with the normal 10 kW inverter, I don't know what the problem is. I understand if I released more than the signed 10kW. But Enea can easily check it, as they installed an energy quality analyzer on my meters for 2 weeks, they can see everything, exactly how much I send. Therefore, in my opinion, it would be a problem if I sent more than I reported.

So I understand that there is no option to connect this 1f hybrid additionally to the network?
So that's all that comes with the off grid option? Winter and autumn is a practically useless inverter.

Illegal in the sense that you cannot feed energy from this inverter into the grid if there is no RfC and therefore no notification to the DSO. You can only use it as off-grid on dedicated electrical circuits.
Tell us what kind of inverter it is and everything will be known.

Regards

this is the inverter
https://easunpower.com/products/easun-power-h...50vdc-grid-tied-touch-screen-inverter-with-ct -sensor

Regards

Added after 3 [minutes]:

I guess it has the RCF because it says it has CT -Control Techniques. Advanced RFC control algorithm.
I guess that’s it.

@waltergraham72 Here is a list of inverters approved for the Polish standard.
http://ptpiree.pl/opracowania/kodeksy-sieci/w...Ws653H-SEchs9kZxxw1cC7W9-hvN_9fwsw7Yx2hXOSNKg

waltergraham72 wrote:

this is the inverter
https://easunpower.com/products/easun-power-h...50vdc-grid-tied-touch-screen-inverter-with-ct -sensor

Regards

Added after 3 [minutes]:

I think it has the RCF because it says it has CT -Control Techniques. Advanced RFC control algorithm.
I guess that`s it.

Unfortunately, you cannot use it as on-grid, only off-grid.

Regards

thanks for the answers. then I already know that I will only use it as off-grid.

Regards
Luke

Gentlemen, I have a question.
As a friend wrote, I have 3 phases connected to phase 1 with a network-generator switch on offgrid.
In addition, "from the meter" I have a 3-phase induction circuit, could I connect an ongrid to this circuit?
The consumption would not be too high because everything would go to the on-grid network anyway and the next question would be whether it would disable the inverter.
Regards.

Hi
By the way, I`m at the stage of making a 4KW installation with EMS management and heat storage - I`ve got the theory right here.
After installing this installation, I would like to connect an off-grid inverter, e.g. Powland 5kW, connect about ~ 9 KW in batteries to it and then run a separate electrical installation.
The question is whether such an inverter is connected in parallel with the on-grid inverter? - I mean the side of PV panels

I know, I know, I could use EMS to charge the battery, but that`s not the point

waltergraham72 wrote:

CT-Control Techniques

This is a limitation of energy transfer to the grid, not sending it to the grid. You install the CT sensor on the mains power supply to the inverter.

You need to have separate panels for the off grid inverter if you want to connect them.

Hello.

I wanted to dig up the topic because I am in the process of combining two systems... on and off grid.

However, I encountered a problem with the power consumption of the Easun SMG ii 5.6kw hybrid inverter. After connecting, the inverter always draws electricity from the grid (import), even though at the same time the on-grid (Sun2000-8ktl) produces and sends the excess to the grid.

Is this maybe a manufacturing defect of SMG??? Maybe connection or settings?

Thanks for your suggestions

How do you think the inverter will work without power? After all, it also needs energy for its own needs.

Of course it needs power.
Only that it takes power from the network, while at the same time other devices draw energy from their own production and the excess is exported.

From the DTS counter, for example, it shows about 7kW of production, home consumption of about 100W and 6.9kW of exports... At the same time, the Eastron counter connected to AC In EASUN shows about 300W of consumption (several devices)

rob160 wrote:

From the DTS counter, for example, it shows about 7kW of production, home consumption of about 100W and 6.9kW of exports... At the same time, the Eastron counter connected to AC In EASUN shows about 300W of consumption (several devices)

These devices need to be switched to the on_grid production phase.