Inverter confusion

[Pocster]

My setup is non standard . 
There are mis understandings on the installers part and mine .

It works - but I’m confused by the inverter …

Suppose you have a 10kw pv array and it is generating 10kw 

Inverter output is limited to 3.68 .

My belief was in this scenario ( assume house load zero ) that 3.68 would go to the grid and rest “ lost “

 

If 10kw pv generated and a Tesla battery ( charge rate 3.66kw ) .

Then shouldn’t 3.66 go to grid and 3.66 go to battery ?

 

Is the inverter limit of 3.68 for *everytjing* I.e that’s the most it can deal with regardless of where it is going ?

 

Hope that question makes sense !

[SteamyTea]

3 minutes ago, pocster said:

My setup is non standard . 

So is your mind.

 

Draw up a circuit diagram.

A lot of it will depend where the generation(s) load(s) and inverter/charge controllers are.

[Pocster]

1 minute ago, SteamyTea said:

So is your mind.

 

Draw up a circuit diagram.

A lot of it will depend where the generation(s) load(s) and inverter/charge controllers are.

Ok . Don’t worry about my non standard setup .

 

pv array 10kw . Pv generation 10kw

inverter export limit 3.66

Should 6.33kw go to house ? ( assuming there’s a load )

 

[Pocster]

Installer says …

My SE DC battery can charge at the highest rate my pv can generate . ( it’s effectively a solar buffer )

So in theory an empty SE battery . Sunny day , pv generation at 7kw . Battery charges - great !

Then battery full .

pv generation still 7kw . Yet only 3.66 will either go to house load and/or grid …

Why ?

Inverter limit of 3.66 applies to current “ going through it “ I.e not just exported but house load ????

Edited May 4, 2023 by pocster

[SteamyTea]

3 minutes ago, pocster said:

Should 6.33kw go to house ? ( assuming there’s a load )

I would have thought so, but as you have multiple inverters/charge controllers, is it a case of your voltage rising too much and that limiting the inverter.

 

and it is kW you (expletive deleted)ing (expletive deleted).

[Pocster]

Just now, SteamyTea said:

I would have thought so, but as you have multiple inverters/charge controllers, is it a case of your voltage rising too much and that limiting the inverter.

 

and it is kW you (expletive deleted)ing (expletive deleted).

Only 1 inverter ( ignore Tesla ) 

Need someone else’s input ! . Yes kwH whatever 

[SteamyTea]

2 minutes ago, pocster said:

Only 1 inverter ( ignore Tesla ) 

I am not sure you can.

One way to test this is is isolate the T and SA storage and plug a couple of heavy loads on.

Then turn on the T and see what happens, then try the same with the SE, then a combo of the two.

Doubt you are currently getting full generation, and if you are, the rain is on its way.

Edited May 4, 2023 by SteamyTea

[Rob99]

22 minutes ago, pocster said:

but I’m confused by the inverter

I'm pondering this exact same question at the moment in planning for a PV and battery system.

The information out there on inverters is quite detailed in the technical specs but the simple questions like "can I use all my PV generation as AC power for house loads or grid export" aren't very obvious.

 

[Pocster]

9 minutes ago, SteamyTea said:

I am not sure you can.

One way to test this is is isolate the T and SA storage and plug a couple of heavy loads on.

Then turn on the T and see what happens, then try the same with the SE, then a combo of the two.

Doubt you are currently getting full generation, and if you are, the rain is on its way.

I’m not touching anything ! 
Someone will chime in 

[Carrerahill]

Reading the conversation between you both was both entertaining and slightly perplexing.

 

Typically you have your PV generation, that comes down into an inverter, or lets just call it a device, because it might be a charge controller, but anyway, that "setup" you would expect would charge the batteries, and or run the house and or export. You are clearly limited on the export limit 16A rule, but that should only impact export, you should still be able to pull more and if that load dropped off it would then clip the excess to keep your export down (in truth it will spike for a fraction of a second when the load comes off, but it works it all out rather fast.

 

So, perhaps your limiting factor is your inverter section of your setup. Maybe it is only a 3.6kW or something? I wonder if the PV installer went under the G98 rules which limit inverter size not thinking about G99 with export limitation and that is now a bottleneck?

[Pocster]

1 minute ago, Rob99 said:

I'm pondering this exact same question at the moment in planning for a PV and battery system.

The information out there on inverters is quite detailed in the technical specs but the simple questions like "can I use all my PV generation as AC power for house loads or grid export" aren't very obvious.

 

Exactly . I assumed I was being dumb ( yeah yeah ) . 
In my scenario as it stands if I didn’t have the SE battery but have a 7kw pv array I’d only ever get 3.66 generated .

Where’s smarty bullocks @Nickfromwales when you need him !

[Carrerahill]

We need a system schematic with model numbers of devices and we will have this sorted by sundown.

 

 

[Pocster]

Just now, Carrerahill said:

Reading the conversation between you both was both entertaining and slightly perplexing.

 

Typically you have your PV generation, that comes down into an inverter, or lets just call it a device, because it might be a charge controller, but anyway, that "setup" you would expect would charge the batteries, and or run the house and or export. You are clearly limited on the export limit 16A rule, but that should only impact export, you should still be able to pull more and if that load dropped off it would then clip the excess to keep your export down (in truth it will spike for a fraction of a second when the load comes off, but it works it all out rather fast.

 

So, perhaps your limiting factor is your inverter section of your setup. Maybe it is only a 3.6kW or something? I wonder if the PV installer went under the G98 rules which limit inverter size not thinking about G99 with export limitation and that is now a bottleneck?

Glad you enjoyed our rubbish .

So as you say what I ask is possible ? ( not interested in increasing export ) .

I *suppose* having a DC battery mitigates the inverter limitations to some extent I.e it could charge at pv maximum generation .

Would the DNO object in principle to g99 ( from g98 ) with a limiter imposed ? . After all I’m interested in my internal bottleneck only …

[Pocster]

3 minutes ago, Carrerahill said:

We need a system schematic with model numbers of devices and we will have this sorted by sundown.

 

 

Ermmmmm . You are an optimist yeah ?

Schematic produced by whom ? 🫤

[Temp]

12 minutes ago, pocster said:

Inverter limit of 3.66 applies to current “ going through it “ I.e not just exported but house load ????

 

Need to see a block diagram of your system.

 

If it looks like this..

 

Then how does the inverter know how much of its output is being used by the house (AC Devices) or exported to the AC Power Grid?  If it can't tell where its going then it will have to limit total output to 3.66kW.

 

One way it could know is if the AC Energy meter block or something in that position on the diagram tells the inverter how much is being exported.

 

Another way would be for the grid connection to go through the inverter on its way into the house.

 

Need that block diagram.

 

 

[Pocster]

4 minutes ago, Temp said:

 

Need to see a block diagram of your system.

 

If it looks like this..

 

Then how does the inverter know how much of its output is being used by the house (AC Devices) or exported to the AC Power Grid?  If it can't tell where its going then it will have to limit total output to 3.66kW.

 

One way it could know is if the AC Energy meter block or something in that position on the diagram tells the inverter how much is being exported.

 

Another way would be for the grid connection to go through the inverter on its way into the house.

 

Need that block diagram.

 

 

Your diagram makes sense . I have no idea of my configuration. I will ask the installer - though at the moment they won’t speak to me . I only sent them 15 emails a few days ago …

[S2D2]

Hybrid inverters have an extra CT clamp close to the meter so they know how much is being exported and can adjust the battery charge accordingly. 

 

As you say, anything DC side of the inverter can soak up excess PV up to its max charge rate even if the inverter is going full pelt pushing to AC.

 

AC side is more complicated, my Solax inverter is set to G98 and will only generate up to 3.68kW AC, regardless of how much the house steals before it hits the meter. Someone in a similar thread stated their inverter could go over 3.68kW if the house was using the difference, so I can only assume that's a g99 setting with export limitation.

[S2D2]

An extra caveat to the above is the inverter will have a max DC rating which will limit the DC side (inverter + battery). For my G98 inverter this is 5.5kW so no point sticking a 10kWp array on it.

[Pocster]

23 minutes ago, S2D2 said:

An extra caveat to the above is the inverter will have a max DC rating which will limit the DC side (inverter + battery). For my G98 inverter this is 5.5kW so no point sticking a 10kWp array on it.

Right ! Helpful thanks .

I guess if I grab my inverter model number would help ?

[S2D2]

Just now, pocster said:

Right ! Helpful thanks .

I guess if I grab my inverter model number would help ?

Yes, it should be stated on the data sheet for the inverter.

[Carrerahill]

1 hour ago, pocster said:

Ermmmmm . You are an optimist yeah ?

Schematic produced by whom ? 🫤

You! Get your crayons out and do a wee scribble for us, where the bits of string go into boxes and things...

 

[Carrerahill]

1 hour ago, pocster said:

Installer says …

My SE DC battery can charge at the highest rate my pv can generate . ( it’s effectively a solar buffer )

So in theory an empty SE battery . Sunny day , pv generation at 7kw . Battery charges - great !

Then battery full .

pv generation still 7kw . Yet only 3.66 will either go to house load and/or grid …

Why ?

Inverter limit of 3.66 applies to current “ going through it “ I.e not just exported but house load ????

Essentially this may be your bottleneck, you see the DNO doesn't even want the inverter to be capable of anything over 16A on a G98 - however, G99 with export limitation would permit this but you then need to fill out the export limitation details to prove you won't blast more than 16A into the system. 

 

Once we see the mfr. & model no. of the inverter you have things will start to slow into place.

 

Even a photo of your PV system showing the units would be good - a clear photo will maybe show what is connected to what and how. 

Edited May 4, 2023 by Carrerahill

[Pocster]

5 minutes ago, Carrerahill said:

Essentially this may be your bottleneck, you see the DNO doesn't even want the inverter to be capable of anything over 16A on a G98 - however, G99 with export limitation would permit this but you then need to fill out the export limitation details to prove you won't blast more than 16A into the system. 

 

Once we see the mfr. & model no. of the inverter you have things will start to slow into place.

 

Even a photo of your PV system showing the units would be good - a clear photo will maybe show what is connected to what and how. 

I’m away on a beach at the moment ( lying in the sun thinking about these things  ) . Will sort photos Saturday ( of inverter etc. not beach 😎 )

[Carrerahill]

52 minutes ago, S2D2 said:

Someone in a similar thread stated their inverter could go over 3.68kW if the house was using the difference, so I can only assume that's a g99 setting with export limitation.

Agreed. A plausible reason for what is happening here is that they went down the G99 with export limitation route, got lazy and just shoved in a G98 which frankly anyone can do with their eyes shut and it is not onerous. 

Edited May 4, 2023 by Carrerahill

[Carrerahill]

6 minutes ago, pocster said:

I’m away on a beach at the moment ( lying in the sun thinking about these things  ) . Will sort photos Saturday ( of inverter etc. not beach 😎 )

Lazy (expletive deleted).