Looking for a big 3 phase hybrid inverter ≥50 kW

[solarbauer]

Hello!

I've been planning a PV install on the roof of my house. (big farm building)

I have space for around 50 kW worth of panels on my south facing roof. I'm not fixed on that number but that's what would fit there.

I also want to get a battery for the whole system and be as self sufficient as possible. My plan is a bank of 64x EVE LF280k cells for a 48V system with around 57 kWh of capacity. I would also not be opposed to building a higher voltage system if there are suitable inverters for that range.

With the bigger loads on my farm my highest sustained power draw is in the range of 15-20kW for 30min-1h a day. My daily energy use on average is 35kWh.

Up until this point I couldn't find any suitable hybrid inverters that would suit my needs. Maybe I'm just looking in the wrong spots.

Do any of you run a similarly sized system? What inverters did you use?
I hope someone here can help me.

 

[Browse]

You can parallel more than one inverter. Get as many as you need to handle your power requirements. If money was no issue, I'd recommend the Sol-Ark 15k. Start with 2 and see if they can handle the loads.

Sol-Ark 15K All-In-One

Sol-Ark® 15K-2P solar hybrid inverter is powerful and military-grade that is scalable, battery-agnostic, and a true whole home backup. Learn more.

www.sol-ark.com

Here are two 12k inverters installed in parallel:

 

[MaximusAnonus]

Don't need 3 phase either.

If he has any motors and is from Europe then he absolutely needs 3-phase.

 

[solarbauer]

Thanks for the answers so far. I absolutely do need 3 phase as those machines use big motors and I want to get most of it from my batteries. Also I'm in Europe, Austria to be exact.

The system should be grid tied so I can sell the rest of the energy and can use the grid should I ever be down on power. 50 kWp of panels is probably a bit overkill but I always read when it comes to solar power you can't have enough.

I read about inverters in parallel, that is an option but I would much prefer some all in one kind of deal if such things exist.

Edit: That Sol-Ark system looks nice but man is that expensive. I would need at least 2 of them to support all the panels and my power draw. For roughly the same price I could get 3x Victron Multiplus II 15000. But that's 15k just for inverters and I was hoping for something more economical.

 

[Hedges]

SMA Sunny Island is one solution, 6 kW per single-phase inverter. Three of them for 3-phase, 18kW continuous, 33kW starting surge (maximum available for your motors.) You could connect up to 36kW of AC coupled single-phase or 3-phase GT PV inverters. Multiple systems can be interconnected, up to about 100 kW of battery inverter, but don't think it can be grid-interactive like a single system. Battery is 48V, lead-acid or lithium.

https://files.sma.de/downloads/SI44M-80H-13-DS-en-30.pdf

Sunny TriPower storage is a 75kW 3-phase battery inverter. It uses a 400V battery.

https://files.sma.de/downloads/STPS60-DS-en-31.pdf

 

[Phil.g00]

The Victron 15kVA's (12kW) can be configured as 3 phase and can be paralleled up to 4/phase.
It has a decent transformer for motor starting current.

These are expensive, but you get what you pay for.

It depends on how much starting current you need. A Victron hybrid can also be ac coupled at a 1:1 ratio with PV inverters.
Transformerless, PV inverters don't handle starting current as well, but they are (can be) less expensive.

A combination may give you what you need depending on your motor sizes.

For such a big system your proposed battery is probably a bit light.

 

[MaximusAnonus]

The system should be grid tied so I can sell the rest of the energy

Research the legal aspects first. The inverter will need special EU licences in order to sell electricity back. At that power you will probably need A LOT of papers, electrical project etc. There is a lot of red tape in EU when you aren't off grid.

BTW the Multiplus II is not yet licenced for electricity resale in Europe AFAIK. So better buy the first one.

 

[solarbauer]

These are expensive, but you get what you pay for.

It depends on how much starting current you need. A Victron hybrid can also be ac coupled at a 1:1 ratio with PV inverters.
Transformerless, PV inverters don't handle starting current as well, but they are (can be) less expensive.

I guess I could use some soft starters (if that's what they're called in english) on the motors to limit the current draw on startup. But I heard about the robust transformers in the Victron inverters and that they can handle a lot.

Also looks like I've got some reading up to do on what AC coupling means..

A combination may give you what you need depending on your motor sizes.

Like a Victron system for the battery related stuff and a pure AC inverter that only feeds e.g a water heater and into the grid?

For such a big system your proposed battery is probably a bit light.

I'm flexible on the size and could always expand later I guess.

 

[solarbauer]

Research the legal aspects first. The inverter will need special EU licences in order to sell electricity back. At that power you will probably need A LOT of papers, electrical project etc. There is a lot of red tape in EU when you aren't off grid.

I'm pretty sure the are some special rules in place for farmers here in Austria that should make larger sized projects a bit more streamlined.

BTW the Multiplus II is not yet licenced for electricity resale in Europe AFAIK. So better buy the first one.

I didn't even think of that, thanks! One more thing to look out for.

I'm always reading up on all the info I can get and watch tons of videos but I guess I'm still very naive in my planning stage.

 

[MaximusAnonus]

If you go for Victron then call your local sales rep and ask how's the licencing process going for the Multiplus II. Might be better to buy the new one and wait a few months in off-grid then once they are licenced you can start selling to the grid.

 

[ArkCabinMan]

You said you wanted to "be as self sufficient as possible."

I dare say, self-sufficiency doesn't include being tied to a grid which requires tons of legal applications, qualifications, inspections and licensing requirements, not to mention how unstable Europe's grid is becoming due to (at least) Russia v. Ukraine.
Protect your home, your farm and your family by building an off-grid power system, and nevermind attempting to sell power back to the grid.

 

[Phil.g00]

I guess I could use some soft starters

The AC wave chopping mechanism is no good for inverters. A VFD is better but only with the extra filters otherwise, the THD may be too high.

 

[Browse]

The AC wave chopping mechanism is no good for inverters. A VFD is better but only with the extra filters otherwise, the THD may be too high.

I don't understand this comment. I have never heard of a soft starter being bad for an inverter. What happens to a waveform after an inverter creates it should have no impact on the inverter operation at all. Large inductive surges would likely have a greater impact on an inverter than anything a quality soft starter would introduce to an AC circuit.

 

[solarbauer]

What happens to a waveform after an inverter creates it should have no impact on the inverter operation at all. Large inductive surges would likely have a greater impact on an inverter than anything a quality soft starter would introduce to an AC circuit.

That would also seems logical to me

 

[solarbauer]

A Victron hybrid can also be ac coupled at a 1:1 ratio with PV inverters.

I did some reading on the Victron website. If I were to use 3x Multiplus-II 15kVA models to get 3 phase power the maximum power going into it from a PV inverter can be 45kVA.

I'm not sure now if I could connect a single big PV inverter to all 3 Victron inverters or each one would need a single 15kVA PV inverter to feed it.

 

[solarbauer]

I did some more reading and found a pretty compelling inverter:

https://sofarsolar.eu/products/hyd-5k20ktl-3ph/

It's for a high voltage battery system. I've seen an install with a DIY 96S LFP battery that works well. Although that was for the 15kW version.

Have any of you got experience with the sofar solar inverters? The 20kW version is ~€3100. It supports up to 30kWp PV input.

I'm thinking 2 of them would do the job for my planned system. They are also certified for grid install where I live.

 

[Hedges]

I guess I could use some soft starters (if that's what they're called in english) on the motors to limit the current draw on startup. But I heard about the robust transformers in the Victron inverters and that they can handle a lot.

Also looks like I've got some reading up to do on what AC coupling means..

I don't understand this comment. I have never heard of a soft starter being bad for an inverter. What happens to a waveform after an inverter creates it should have no impact on the inverter operation at all.

"AC Coupling" means connecting a grid-tied photovoltaic inverter to your battery inverter, and operating the system while disconnected from utility grid. The ones I'm familiar with use increasing frequency to signal for power reduction. My grid is 60 Hz, and between 61 Hz and 62 Hz, PV inverter power output ramps down from 100% to 0%. Many inverters now do that, with a frequency range closer to nominal.

We see soft-starters (and hard-start kits) for single phase motors. Typically so a generator on an RV can start the rooftop AC.
For 3-phase motors, VFD can ramp up speed very gently, no surge current at all.

I put in a Hitachi VFD an 2 HP pool pump, powered by 120/240V split phase (single phase.) I found the power line harmonics from VFD upset my GT PV Sunny Boy inverters. Possibly only if VFD is running at the moment Sunny Boy wakes up and checks the grid.

What you would like is power-factor corrected VFD. Maybe VFD won't cause you problems, if you don't have AC coupling. You could start up your motor with VFD, then throw a transfer switch and run motor directly from your inverters.

I've set up a 3-phase SMA system, haven't loaded it very heavily yet. Only ran a 2 HP 3-phase motor (no VFD) on my air compressor. At 6A that was only 15% of inverter rating, and even 35A starting surge didn't exceed continuous rating.

 

[Phil.g00]

I'm not sure now if I could connect a single big PV inverter to all 3 Victron inverters or each one would need a single 15kVA PV inverter to feed it.

Either is an option or even multiple smaller single-phase PV inverters on each phase.

 

[Phil.g00]

I don't understand this comment. I have never heard of a soft starter being bad for an inverter. What happens to a waveform after an inverter creates it should have no impact on the inverter operation at all. Large inductive surges would likely have a greater impact on an inverter than anything a quality soft starter would introduce to an AC circuit.

The inverter doesn't create the current waveform the load does. Any waveform even a square wave can be broken down into a combination of sine waves at different frequencies and phase relationships. (That is the basis of the Fourier series).
So a none sine wave is full of harmonics, which if they were a percentage of the mighty grid power system would still make up a small % and be of no real consequence. However, as a % of a far smaller inverter output, they do make a significant portion of the total.

 

[Browse]

The inverter doesn't create the current waveform the load does. Any waveform even a square wave can be broken down into a combination of sine waves at different frequencies and phase relationships. (That is the basis of the Fourier series).
So a none sine wave is full of harmonics, which if they were a percentage of the mighty grid power system would still make up a small % and be of no real consequence. However, as a % of a far smaller inverter output, they do make a significant portion of the total.

Maybe you're using the wrong kind of soft starter. Watch this video...Matteo designed the EasyStart and goes into great detail as to how it functions, along with the many safeguards built into the circuitry: