Title: Combining 7-10 KVA UPS, Bacterial Modules & Photovoltaic Panels: Is it Efficient?

Hello,

I am thinking about connecting a 7-10 KVA UPS with additional bacterial modules to the electrical installation at home. At the moment I have photovoltaic panels with microinverters connected before the differential and the question is how should I connect the UPS and does it make sense at all, or is it better to choose some other solution to maintain the power supply than the UPS? When connecting, I take the UPS power from the differential and then go directly to Sy? Does it give the second differential and only Sy?

Doom wrote:

At the moment I have photovoltaic panels with microinverters connected before the differential

Can your friend explain what he means? because it sounds sinister.
Is it off-grid or on-grid?

Of course, I'm in a hurry to explain, the installation is on-grid on microinverters from which ~ 230V comes out directly, world-class specialists, as they connected it, from what I remember they plugged in the same way as the power supply from the meter, i.e. in the input of the RCD protection, while the panels themselves they are on the ground and have their own protections, both under the panels themselves and at home, I don't know what kind because I haven't checked. They also moaned something that the N wire was badly secured because someone screwed it upside down in the protection, but in the end they did nothing about it, they just plugged in, fired, did not explode, so they said it would be ok. Is everything ok, only that it's a house in the countryside and only brothers-in-law who used to build a nest around it. In general, what I would like to achieve - if possible, is for the system to work hybrid, if the electricity from the supplier fails, some relay will switch to the UPS and the panels will continue to produce/charge the UPS and it will power the house. When the electricity comes back from the supplier, the whole thing will switch back. Unfortunately, even though we live in the 21st century, there are still power outages, sometimes for half a day. As I wrote, it's a house in the country and generally I don't live there permanently, but it would be nice if the fridge didn't defrost, the heating worked in the winter, etc.

If it is an on-grid installation, you should not interfere with its 230V part under any circumstances - because it is against the law and dangerous, and even more so, hooking on a UPS guerrilla.
If so, the inverter itself should have the option of connecting batteries - this is the only official option (there are such).

And I thought this would be an easy and quick question ;-)

1. I'm not going to change anything myself, but before I throw 12-15 thousand for a 10 kVA UPS, I'd like to know if it makes sense. Is it better to do it differently, I also have 2 generators that I can use, but the cost of their work will be higher than charging batteries from photovoltaics and using them in the event of a power outage.
2. It is impossible to connect an ordinary inverter here, microinverters are under each group of 4 panels, there is not one device that manages it.
3. IMO, power generators are somehow connected to the network so as not to kill anyone in the event of a power failure, the current does not go back because the external line is cut off - at least it seems to me and it can be done on a relay that will switch to the UPS in when the coil loses power and returns to power from the city when the coil is powered again.

Doom wrote:

3. IMO power generators are somehow connected to the grid so that they do not kill anyone in the event of a power outage

And here's the thing, there is no cosmic possibility that reverse voltage will appear in the network when the main power fails.
So. we have either a physical manual switch (1-0-1) or a certified automatic switch.

Well, no problem, there are a few such automatic switches, but if you connect the UPS to the PV so that the inverters continue to work, then the same voltage will power the UPS later, is it not a problem? Can a UPS power itself?

Can you draw what you want to achieve? Because I still don't quite understand.
Do you just want to have "electricity from the battery?"

Instead of a UPS, it is better to use an off-grid inverter/inverters.
Then we have a lot of room for optimal use.
E.g
1. We connect AC to the inverter, from the inverter to power the house, the batteries are used only in the event of an AC failure, which is basically a UPS function, because the switching will be automatic.

2. The above, only in the absence of AC, we connect the panels and then the installation is powered from the panels or the battery, or together, if the power of the panels is sufficient, the battery is charged.

3. We can connect panels in addition to AC permanently. The downside is that if the load is small and the batteries are charged, the PV energy will not be used.

4. In the absence of AC, PV energy and battery discharge, you can connect a power generator that, in addition to current consumption, can charge the battery.

5. In addition to emergency power, batteries can be used as energy storage. That is, discharge to a certain level, increasing the level of self-consumption.

And you can probably come up with some other arrangement.

How does the energy storage work? When there is no electricity from the panels, the electricity from the storage is used first and then from the grid? Can this be achieved with your own batteries and some device? Ready-made kits are, to put it mildly, expensive.
In general, the whole thing boils down to the fact that a device that will manage all these energy sources would be useful. We have 230v from panels, 230v from batteries, 230v from the supplier. During normal operation, the electricity from the panels should power the house and charge the battery, the surplus goes to the grid, at night the power goes from the battery. When the batteries run out, electricity is drawn from the grid. In the event of a power failure, the power supply from the network is disconnected and electricity is generated from the batteries, which allows the panels to continue working, charging the batteries and powering the house. That's the goal :-)

It seems to me that the network failure problem can be solved with 2 sets of automatic switches. One disconnects the network when there is no power supply from the network, the other switches the panels to battery power (behind the inverter/converter increasing 12v/24v/48v to 230v). After the power supply is restored, the relays switch to mains operation.

Will the use of a hybrid solar inverter solve my problem? 2 automatic switches can be used to isolate the panels from mains power. Below is a paint drawing The panels must be connected to 230v to produce.

Doom wrote:

Will the use of a hybrid solar inverter solve my problem?

Exactly. Excess energy can be stored in batteries instead of "sold". In the long run, it will probably be the cheapest, UPS with decent power in inches are not cheap + alpine combinations to plug it into the network and not kill yourself or anyone else.

Using this type of inverter you do not need to use any switches. The inverter controls everything. What is to be a priority is set in the inverter.

kosmos99 wrote:

Using this type of inverter you do not need to use any switches. The inverter controls everything. What is to be a priority is set in the inverter.

In what is better, you can even set balances/plans (loading during the day and at night with low consumption, you can draw from the battery instead of the network), depending on what pays off more in a given situation.

But the inverter needs 230v power from the grid and DC voltage from the panels and I want to give it 230v AC from the grid and 230v AC from the panels.

Doom wrote:

But the inverter needs 230v mains power and DC voltage

It doesn't have to be both, just one is enough.

Doom wrote:

230v AC from panels.

The panels give DC not AC.

Doom wrote:

But the inverter needs 230v power from the grid and DC voltage from the panels and I want to give it 230v AC from the grid and 230v AC from the panels.

You messed up a bit with these microinverters and now you're doing wonders... :/
Can't give DC?

Unfortunately, I will not replace them and I am more satisfied with them than I would be with a single inverter, my friend has 10kWp with an inverter and has less production than me with 6.3kWp with microinverters, they start much earlier and in the event of a restart due to too much voltage, they produce again after a few minutes , my friend's production starts 20-30 minutes after the restart and in the morning they start production much later. I need lower DC voltage for production. That's why I want to keep them.

Due to the fact that the panels come with 230v AC, I think that these two automatic switches will solve the problem.

Doom wrote:

buddy has 10kwp with inverter and has less production than me on 6.3kwp

Such a big difference is certainly not related only to the type of inverter. Other considerations are responsible for this.


So I understand that direct connection of panels to offgrid is not an option?
Now the question is what will be cheaper traditional UPS or off-grid with batteries.
In the case of off-grid, it can also be used as an energy storage.

They'll do it, but it won't be cheap either.
https://tiny.pl/9rdsh
You know, these are certified items...

Doom wrote:

Due to the fact that the panels come with 230v AC, I think that these two automatic switches will solve the problem.

What are these switches for? Is it not enough to power the whole thing via a UPS or an inverter?
That is, the UPS when AC is present, works in buffer mode, when it is absent, it switches to battery?

kosmos99 wrote:

What are these switches for? Is it not enough to power the whole thing via a UPS or an inverter?
That is, the UPS works buffer when AC is present, switches to battery when not present?

Without switches, in the event of a power outage from the mains, it could kill someone. When the electricity from the grid fails, neither the panels nor the UPS have the right to operate and let the electricity flow into the grid. The power to the operator must be cut off. Otherwise, someone who will repair it "on the pole" or in the MV or LV switchgear may die.

Added after 3 [minutes]:

kosmos99 wrote:

In the case of off-grid, it can also be used as an energy storage.

Unfortunately, connecting the panels directly to the inverter is out of the question. I don't know what exactly is the reason, but more production is mainly on bad days. He on 3kwh, I have about 7kwh - these are the worst days this month. When the weather is nice, of course, he has better production, but this is due to the number of panels, etc.

What are the advantages of an energy storage?

Doom wrote:

Without switches, in the event of a power outage from the mains, it could kill someone. When the electricity from the grid fails, neither the panels nor the UPS have the right to operate and let the electricity flow into the grid. The power to the operator must be cut off. Otherwise, someone who will repair it "on the pole" or in the MV or LV switchgear may die.

Yes, you need to cut power to the operator, and one of the reasons is that you have little chance of your installation getting up and running power to all your neighbors who are on the same network with you.

Generally, you put in an automatic contactor that will cut off the mains in the absence of power.
How the UPS behaves with an inverter needs to be tested, there is a good chance that the 230AC voltage will quickly exceed 250AC and the inverters will turn off if there is no large "load" at home or by charging the UPS. The second issue, how the inverters will behave when switching from the grid to the UPS, is about synchronization with the grid.

wilk125 wrote:

Doom wrote:

Without switches, in the event of a power outage from the mains, it could kill someone. When the electricity from the grid fails, neither the panels nor the UPS have the right to operate and let the electricity flow into the grid. The power to the operator must be cut off. Otherwise, someone who will repair it "on the pole" or in the MV or LV switchgear may die.

Yes, you need to cut power to the operator, and one of the reasons is that you have little chance of your installation getting up and running power to all your neighbors who are on the same network with you.

Generally, you put in an automatic contactor that will cut off the mains in the absence of power.
How the UPS behaves with an inverter needs to be tested, there is a good chance that the 230AC voltage will quickly exceed 250AC and the inverters will turn off if there is no large "load" at home or by charging the UPS. The second issue, how the inverters will behave when switching from the grid to the UPS, is about synchronization with the grid.

I agree, there are a lot of problems.
I especially wanted to open my friend's eyes to the costs.
https://tiny.pl/9rdsh
It won't be cheap and even so ciul one knows how it will all behave.

Apart from the costs, playing is dangerous to health and life.
A big (industrial) UPS is too damn expensive.
It's time to rethink the line of reasoning if it makes sense to go for it.

Doom wrote:

Without switches, in the event of a power outage from the mains, it could kill someone. When the electricity from the grid fails, neither the panels nor the UPS have the right to operate and let the electricity flow into the grid. The power to the operator must be cut off. Otherwise, someone who will repair it "on the pole" or in the MV or LV switchgear may die.

I don't think we understand each other. Since the UPS has a power of 10 kVA, why not use it to power all circuits, except for the microwaves, which will be connected before the UPS. Alternatively, before the UPS, plug in those that do not need to have an emergency power supply. So in the event of a grid failure, nothing will go to the line, because the PV will turn off due to the lack of AC, and the UPS will only supply the load circuits.

Doom wrote:

What are the advantages of an energy storage?

Such that you have better self-consumption and you give less to the network, and you use more on an ongoing basis from the panels.

kosmos99 wrote:

Such that you have better self-consumption and you give less to the network, and you use more on an ongoing basis from the panels.

A colleague will add battery depreciation, Pb / AGM are expensive to buy and not necessarily long-lived. Slightly counting on a good morning, you need 1000Ah (to run the laundry at night) and still have a supply for "fridge and TV".
Assuming 100% efficiency of the 200Ah battery, it will give about 2kWh (which is utopian) because loaded with maximum current it will die like a jackdaw after 15 minutes;p (that's why you need a much larger capacity).
Generally, it is better to have a UPS with a 48-110V (DC) input, i.e. a battery in series (lower current), but this is only a minor remark to the whole. So the costs are going up astronomically all the time

Dude, but we're not considering profitability per se, just the situation:

UPS vs Off-Grid Inverter

UPS only emergency power function.
Off - Grid can also (but does not have to) be a warehouse. Of course, the warehouse does not have to suffice for the entire demand, we configure to what level the batteries are to be discharged so as not to significantly reduce their capacity.
The inverter input for the battery is 48V, so 4 in series, but I think 8 pieces of 100Ah will be the most optimal. Then we have 9.6kWh, 5kWh to be used in an emergency (discharging to 50% capacity). A power generator can be connected to this offa, which, in addition to powering the receivers, will charge the batteries.

In addition, you can set the time range in the inverter in which the battery can be charged, i.e. an hour a day. Then the panels behind the ongrid actually charge the batteries.

Therefore, it would be necessary to consider both options in terms of price. The biggest cost is the batteries, but they are needed in both cases.

kosmos99 wrote:

Dude, but we're not considering profitability per se, just the situation:

UPS vs Off-Grid Inverter

Of course.

But we have On-grid and it's hard to marry it reasonably.

It is best to insert a heat accumulator and simply heat the hut/DHW , heaters do not care from where and how they are supplied.

The author is talking about emergency power. The heat accumulator will not provide electricity
With this warehouse, I gave only such a plus to the off-grid installation above the UPS, it does not have to be used.

bestboy21 wrote:

But we have On-grid and it's hard to marry it reasonably.

If the offgrid can be programmed when the batteries are to be charged, it can be done indirectly by setting the daytime hours. Then there is self-consumption and avoidance of the discount. The fact that the energy will be transformed twice (from the panels to the on-grid and from the on-grid to the battery) but since there is no way out, it's always something.
At home, I want to do something like this only with directly connected 2kW PV panels. Starting the unit, especially in winter, is not very convenient.

Wait a minute, aren't on-grid installations sometimes protected against reverse voltage? (It's logical that they should be).

So I would solve it with an AZR automatic unit with an auxiliary contactor that will cut off the "outputs" of the inverters just in case.

The three-phase ongrid inverter will not be excited by the voltage from a single-phase UPS or Offgrid

Added after 6 [minutes]:

Anyway, if anything, the AC cable from Ongrid can be put before the UPS or Offgrid, then these systems will not give voltage to the ongrid at all.
I don't think we fully understand this SR.
UPS and Off work differently than ongrid. The former have an AC input and output, so in buffer operation they cannot provide AC to the network. Ongrid has a common AC circuit for the input and output, hence the difference and if it woke up it could power the network.
Unless you want to connect it in parallel like the generator, then ATS is needed. But does it make sense to do that?