High voltage DC inverters?

[realpinochet]

I found a few guys on youtube using High voltage / Low frequency inverters and after reviewing their motives I agree it seems like a much better option in efficiency and durability. Seems like it's less wiring in general and smaller wires due to less current. It would reduce heat in the batteries and the inverter which in theory would be good, as mentioned, for efficiency and durability. I found a guy using a Aims inverter for his shop and a gentlemen on youtube using a sandi inverter for his rural property. The sandi is a high voltage / Low frequency inverter that has the ability to have the PV connected to the inverter and run without a battery and additionally connected to the grid for grid assist when batteries are too low. It appears the newer modules have a built in charger to. It's a isolation transformer so you have full isolation from the grid, this should eliminate the G/N bound issues, and no backfeed. I believe he said he's using the 30KW version and it cost him like 5 grand or so..could be wrong on that. I'm looking at the 40KW version. The two issues I see are:

1. There's not much option for HV batteries unless you build your own.
2. The inverters don't appear to be stackable so you can run two for redundancy. (I was thinking of using 2x20KW)

As for the batteries, can you take standard rack mount batteries like the EG4 and connect them in series to say 250-400 VDC? Per this article maybe..but maybe not on the ones that have built in circuit breakers that are not rated for such high voltage. I haven't got into researching batteries much yet. Seems like most people are using those blue bricks that come out of EV/s. Personally I'd rather buy ones that just needed to be connected in series and not build the whole battery.

If this theory has any validity ..then why haven't the big guys like outback,schneider,solark got into high voltage solutions for residential installs?

Summery, seems like you can get a heavy duty inverter capable of high output for a decent price. Reliability and durability should be better over time due to less heat. The ability to use less and smaller wire. A quick search here seemed to have people mention this but I haven't seen a in length technical discussion on it for pros / cons. Has anybody here used a inverter like this.

https://www.bsl-battery.com/series-connection-and-parallel-connection-of-lithium-solar-batteries.html

Sandi:

Off Grid Inverter-Zhejiang Sandi Electric Co.,Ltd

www.sandi.cc

3phase:

30KW 30,000 PURE SINE POWER INVERTER CHARGER 300 VDC 208 VAC THREE PHASE

That’s right! You read it correctly. We offer HUGE DC to AC pure sine inverter chargers 30KW up to 200KW. Introducing the NEW AIMS extra large power inverter charger product line in 240 split phase or 208 three phase. This off-grid, back up power inverter is perfect for businesses, large homes...

www.aimscorp.net

Youtube:

https://www.youtube.com/@mikeg2321/videos

 

[Rednecktek]

It's something I've been wondering about too. So much on the lower end says to keep fuses below 200a, but on the high end your 10k, 12k, 15k are still running 48v which puts the fusing and wiring in the 300a+ range. You would think that at those sizes we'd have 96v systems by now.

 

[RSahan]

Deye released the HV inverters including a 50kw few months ago. I guess Solark will release those in the US market in near future

If this theory has any validity ..then why haven't the big guys like outback,schneider,solark got into high voltage solutions for residential installs?

 

[robby]

There are a lot of upsides to using a HV system.
Fortress Power is another company that is also branching off in that direction. There are two downsides to HV system that I think are giving most companies a bit hesitation.
To get to let’s say 360Vdc you’re going to need 100 cells in series. While these will be smaller and lower in amparage you are still dealing with a lot of cells that can be seriously effected by even a few cells underperforming .
The second is field servicing of the batteries. There is very little room for errors when servicing or wiring these systems

 

[Off Grid Solar UK]

It's something I've been wondering about too. So much on the lower end says to keep fuses below 200a, but on the high end your 10k, 12k, 15k are still running 48v which puts the fusing and wiring in the 300a+ range. You would think that at those sizes we'd have 96v systems by now.

Indeed Sigineer do a 96v LF inverter that cab have Tesla module parameters already built in thanks to Jack Ricard.

 

[timselectric]

Safety is the main concern for high voltage batteries.
Those voltages will easily take a life. And produce arcs like in Frankenstein's lab.

 

[pollenface]

XIJIA do a 110v Inverter

 

[littleharbor2]

Safety is the main concern for high voltage batteries.
Those voltages will easily take a life. And produce arcs like in Frankenstein's lab.

Probably the main reason 48 Vdc is the upper end of availability to John Q. Public.

 

[realpinochet]

Deye released the HV inverters including a 50kw few months ago. I guess Solark will release those in the US market in near future

That's 50Kw out ..what's the DC input side?

 

[RSahan]

That's 50Kw out ..what's the DC input side?

65Kw. https://www.deyeinverter.com/produc...-50ksg01hp3eubm2-3-4-25-50kw-three-phase.html

 

[realpinochet]

There are a lot of upsides to using a HV system.
Fortress Power is another company that is also branching off in that direction. There are two downsides to HV system that I think are giving most companies a bit hesitation.
To get to let’s say 360Vdc you’re going to need 100 cells in series. While these will be smaller and lower in amparage you are still dealing with a lot of cells that can be seriously effected by even a few cells underperforming .
The second is field servicing of the batteries. There is very little room for errors when servicing or wiring these systems

Good point. One video I was watching where the guy had a HV setup....his bms, custom bms, monitored each cell for issues so it could be replaced before it became a big issue..hopefully. A neat thing about his bms was you could tell the bms to identify the cell. So for example cell 102 was showing to be a issue, you could tell the bms to turn on the led light for that cell and it would flash a red led that was on that cell. I'll post the video if I can find it again.

 

[Ampster]

That's 50Kw out ..what's the DC input side?

Apparently 160 to 800 DC battery volts.

 

[CoolWill]

As code goes, in the US, once you get above 48 volts, things change drastically. With a 48 volt battery, you don't have to worry about grounding or protecting the conductors in conduit. Above 48 volts, all that screwing fuse blocks to plywood goes out the window.

 

[realpinochet]

Safety is the main concern for high voltage batteries.
Those voltages will easily take a life. And produce arcs like in Frankenstein's lab.

There's was to mitigate some of this right? I believe you're an electrician. There's protective gear I see them wearing on youtube for arc flash...like face shields and gloves. But, to your point is exactly why I wanted a battery professionally made where It's plug and play not a diy one. Just plug the battery in via a Anderson pole or something. But also, we're playing with 500-600 VDC from the solar panels into the charge controllers right? Isn't this similar.

 

[realpinochet]

As code goes, in the US, once you get above 48 volts, things change drastically. With a 48 volt battery, you don't have to worry about grounding or protecting the conductors in conduit. Above 48 volts, all that screwing fuse blocks to plywood goes out the window.

Should be the case at any voltage.

 

[realpinochet]

Can you connect in series the server rack batteries like eg4? That way you could leave the circuit breakers off until you get them all connected.

 

[timselectric]

There's was to mitigate some of this right? I believe you're an electrician. There's protective gear I see them wearing on youtube for arc flash...like face shields and gloves. But, to your point is exactly why I wanted a battery professionally made where It's plug and play not a diy one. Just plug the battery in via a Anderson pole or something. But also, we're playing with 500-600 VDC from the solar panels into the charge controllers right? Isn't this similar.

Not the same as solar. Because of the available short circuit current.
Also once you get above 600v, you're into the next level of conductors, enclosures, and OCP equipment.
Can it be done, yes.
Should it be done in a residential setting, not in my opinion.

 

[timselectric]

Should be the case at any voltage.

Low voltage (less than 80v) is touch safe. (It won't kill you)
Above that extra precautions must be taken.

 

[timselectric]

Can you connect in series the server rack batteries like eg4? That way you could leave the circuit breakers off until you get them all connected.

The BMS's aren't rated for the voltage. And the breakers probably aren't either.

 

[realpinochet]

Here's the video where the gentlemen designs his own bms to identify individual cells via a led light, it also controls a relay or something in the power panel to cut off power if there's a issue. I'd like to learn more about that.