New Here - Audacious Plans Afoot - 8000kWh System Coming Soon

[AutoMater]

In my original post I asked for thoughts or advice about connecting multiple batteries together with bus bars and sharing them with ALL inverters. Has anyone done that? Any thoughts or advice? I will have 3 inverters, one for each 200amp electrical panel, and possibly 2 per panel. Then I will have that 3 times (1-2 inverters for each of 3 200amp panels). So I am trying to figure out how to share all the batteries across all the inverters to avoid effectively having 3 separate systems.

Also, another option might be to master/slave all the inverters needed and dump all the power into some sort of trough that then feeds all 3 of the 200amp panels. Is that maybe a better way to do it?? (For what it's worth, the power now comes from the meter, goes into a trough, and breaks into the lines that go to the three 200 amp panels)

 

[Hedges]

I think that should work fine, and PV harvested by any is available in batteries for all.
So long as multiple A/C or other big motors don't try to start at the same time, the larger battery will help with that. Try to sequence such motors in some way.

Several of the big hybrids support a number of inverters in parallel, which means they would agree on how to charge battery. You could parallel all inverters and feed all panels (as your second paragraph indicates), or you could keep AC outputs separate; I don't think they care either way.

My system has 4x SI 6048US (120V each) wired 2p2s. I could have two separate 2s systems sharing battery and communication bus, and I think that would work fine except for one situation: If each has AC coupled PV (my system does, it has Sunny Boys), and if the AC coupled wattage exceeded what the SI 6048US could convert to DC, I think that would be a problem.

That's not likely if you use AIO, with mostly DC coupled PV and maybe a small amount of AC coupled.

 

[wpns]

In my original post I asked for thoughts or advice about connecting multiple batteries together with bus bars and sharing them with ALL inverters. Has anyone done that? Any thoughts or advice? I will have 3 inverters, one for each 200amp electrical panel, and possibly 2 per panel. Then I will have that 3 times (1-2 inverters for each of 3 200amp panels). So I am trying to figure out how to share all the batteries across all the inverters to avoid effectively having 3 separate systems.

In fact, that’s how EG4 ESS (18Kpv plus PowePro) is supposed to be wired. The internal bus bars are good for 600A so you may not need external ones.

Please note (again) that 18Kpv is essentially a 50 amp (AC) inverter, and needs two PowerPro batteries per inverter to provide the DC power peaks. I don’t think one 18Kpv inverter per 200A AC panel is going to work very well for you.

You really need to do an energy audit to know what your peak (KW) load is, and your daily(?) KWHR requirements are before throwing hardware in.

 

[AutoMater]

I am getting conflicting info from the local solar guy, and signature solar.

You guys seem to be saying that I should be able to do it more like the following, yes?

Or should we master / slave all inverters together?

I’m struggling to figure out how to go about this “the right way”.

 

[wpns]

Are all three inverters co-located? If so, parallel the inverters and tie the battery banks together. If not, treat them as separate houses.

And one 18Kpv may be too small for a 200A panel. Sorry I forgot to mention that before

 

[AutoMater]

Are all three inverters co-located? If so, parallel the inverters and tie the battery banks together. If not, treat them as separate houses.

And one 18Kpv may be too small for a 200A panel. Sorry I forgot to mention that before

Yes, all three of the 200amp panels are together 2 feet from each other.

Assume there will be 2 inverters for each 200amp panel if that is what is needed.

Could you be more verbose about "parallel the inverters and tie the battery banks together". If I parallel the inverters wouldn't that mean I need to dump it all into a bus bar and feed the three panels from there? How can I "tie the battery banks together"? According to the manual only 3 batteries should be paralleled per inverter. I need like 10-12 (final number TBD)

 

[wpns]

Could you be more verbose about "parallel the inverters and tie the battery banks together". If I parallel the inverters wouldn't that mean I need to dump it all into a bus bar and feed the three panels from there? How can I "tie the battery banks together"? According to the manual only 3 batteries should be paralleled per inverter. I need like 10-12 (final number TBD)

Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

 

[AutoMater]

Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

To be clear, the way it works now is the grid power goes into a trough where there are bus bars that connect the meter to the lines that run to each of the 3 disconnects (that then go to the panels inside the house).

So I suppose this would stay the same except from those bus bars I would run to the inverters, then out of the inverters and to another set of bus bars, then back into the disconnects. Or, how do the

Put the Grid inputs of all the inverters together into an AC combiner box fed from your 600(?) amp main feed.

Put the Load outputs of all the inverters together into a different AC combiner box. It should be rated for at least 50 amps times the number of inverters you have.

Connect a minimum of two PowerPro batteries to each inverter.

Use the busbars on the batteries to connect the batteries together.

Use parallel RJ45 cables between the inverters (see the manual for details).

Set one inverter to Master and the others to Slave as per the manual.

Thanks a lot for this. I didn't even see your reply till after I called Signature Solar and talked to their techs today and they basically said the same thing you just said.

What I am thinking about right now and trying to figure out how to deal with is what all pieces should be where. Here is something I drew just now. I took a look on ebay (just to gauge what a 600 amp panel costs) and holy cow! I am hoping you guys or one of the electricians has some sort of idea about how to go about this cheaper.

I am also including an image of my current electrical setup. The trough in the bottom right is where the grid power comes in from the meter (left). In the trough there are bus bars where they just connect together those wires with the wires that are going into the 3 disconnects you see above it.

I am imagining coming from the meter, through the trough, out the bottom of it, in conduit over to where the solar stuff will be, into the 600 amp panel I have drawn (or possibly 6 disconnects if that is possible / easier / cheaper), then you can see the rest on the drawing. The wires from the "combiner box" exiting the inverters would go in conduit, back into the trough, and back into the disconnects going into the house.

Thoughts?

 

[wpns]

Sorry I forgot to mention: Your first step should be an energy audit.

600 amp service split to 3 300A panels is an insane amount of power (144KW), but it’s unlikely you actually need all that. You paid a fortune for your current setup, you either need to do it again with 12(!) inverters in the middle or figure out what you actually need.

I fell into this trap myself, I’ve got a 200A service with a 25KVA (100A) transformer, so I was able to significantly downsize my wiring requirements (and saved thousands in wire costs) when I moved my transformer. I’ve got a neighbor with a 400A feed who shares a 25 KVA transformer with two other houses. Know what you need _first_.

 

[jpwhit]

These are likely a good part of your high energy usage. And whoever installed them grossly violated the minimum distance between units. Amana calls for a minimum of 20" between units for residential and 24" for light commercial. You should be going by light commercial recommendations with 4 units. The poor airflow around the units is going to really cut down on efficiency. They also look like they're old enough that replacement wouldn't be a bad idea in general.

 

[jpwhit]

I think you should be connecting in at the 600amp panel level because power usage across the 200amp panels will vary a lot from panel to panel and power will end up feeding back between panels through the 600amp panel anyway. And as @wpns said, you need to figure out what your max average usage is, because the panel and service max ratings have little to do with your max power needed.

With the design you've sketched out, I would be concerned with reliability of having so many individual parts. I think you should be looking at light commercial inverters with much higher KW ratings if you really need that much power.

If it were my house, I'd also look at the new Tesla Powerwall 3. Each one can surge up to 15kw and you can install as many as 10, maybe more. Each one also has 6 MPPT solar inputs so you'd have 24 MPPT inputs if you did 4 powerwalls for example. You can go on the Tesla website and do a system design in seconds to get ideal of the options.

Also, any Solar installer that certified with Tesla can also install different layouts. But I've generally found it's hard to beat the price and quality of install of the Tesla installers.