Pass Through Current Limitations in SolArk 12k

[mcorner]

I am in MA and am looking to install whole house battery backup and 25kW of solar. I have an installer doing the actual install, but he is pretty close to DIY and the design is a collaborative process.

background: In MA the law recently changed (and the DPU is catching up) to allow up to 25kW of inverter capacity on single phase service with full net metering. Previous to this the limit was 10kW and after that you have to apply to the capacity cap and only get 60% net metering.

I have 200amp service and have a lot of loads and am planning on an all electric house (two large heat pumps etc). So my goal is to get to as close as possible to 200amps of current into my load panel. Since this is whole house backup...no load panel. Also, no generator, probably two Fortress evalult max batteries.

Also in MA only certain inverters can participate in demand response for the batteries, so I pretty much have to use SolArk.

- Two SolArk 15ks won't fly because that is 30kW of "nameplate capacity". Software export limits are not acceptable for the electric company.

- Three SolArk 8ks would work since they can pass 3*63Amps = 189Amps. Not bad.

- But is there a way to use two Solark 12ks? I ask because it would save $4500 over three SolArk 12ks and some wiring. Can you use an external transfer switch to somehow feed the inverters and the panel? Seems like this would create a problem. Is there something I am missing?

 

[Nobodybusiness]

I’m trying to figure out why you need 200 amps?

The panel is rated at 200 amp but you really don’t use that.
I have a 400 amp service and peak draw is 60 amps.

I run 2 Sol-ark 12ks and it works great.

Just trying to understand what you want or need..

 

[Bkord]

2 12ks is 18k export. Plus 6k to batteries. 2 12ks can communicate. I don’t know if a 15 and 12k can communicate. That would get yo u closer to 25k. I have an all electric house and have never pulled more than 100a

 

[RV10flyer]

I am in MA and am looking to install whole house battery backup and 25kW of solar. I have an installer doing the actual install, but he is pretty close to DIY and the design is a collaborative process.

background: In MA the law recently changed (and the DPU is catching up) to allow up to 25kW of inverter capacity on single phase service with full net metering. Previous to this the limit was 10kW and after that you have to apply to the capacity cap and only get 60% net metering.

I have 200amp service and have a lot of loads and am planning on an all electric house (two large heat pumps etc). So my goal is to get to as close as possible to 200amps of current into my load panel. Since this is whole house backup...no load panel. Also, no generator, probably two Fortress evalult max batteries.

Also in MA only certain inverters can participate in demand response for the batteries, so I pretty much have to use SolArk.

- Two SolArk 15ks won't fly because that is 30kW of "nameplate capacity". Software export limits are not acceptable for the electric company.

- Three SolArk 8ks would work since they can pass 3*63Amps = 189Amps. Not bad.

- But is there a way to use two Solark 12ks? I ask because it would save $4500 over three SolArk 12ks and some wiring. Can you use an external transfer switch to somehow feed the inverters and the panel? Seems like this would create a problem. Is there something I am missing?

Max ac passthrough per 12K 63A L-L 240V.

I'm totally off-grid. I ask the power co to turn off our meter. So no grid input on my system.

Make sure you have either variable speed heat pump systems 20 Seer and above or install micro air soft start on your heat pumps. While your HVAC guy is there, have him install toggle switches that will allow you to open the "W" low voltage circuit to your electric heat kits.

Back when I was on the grid, I would have to turn on our heat pumps, electric heat and everything else in the house to reach the max 200 A on my service. What are you doing that you would need even close to 200A? I am now running off of two 12K's and have got up to 16,000 W. Pretty close to the 37.5A output on each one.

 

[Danke]

The discussion on the 15k seem to have confusion on AC coupling.

I’d call Sol-Ark, but you may be able to exceed 15 kW with a mix of DC to MPPTs and micro inverters to GEN input.

 

[RV10flyer]

2 12ks is 18k export. Plus 6k to batteries. 2 12ks can communicate. I don’t know if a 15 and 12k can communicate. That would get yo u closer to 25k. I have an all electric house and have never pulled more than 100a

No mixing 12K and 15K.

 

[Nobodybusiness]

D

 

[mcorner]

Hey, thanks for the help!

I have two EVs, so that can be 80Amps right there. It is a large house (5k+sqft) and I am going to end up with two 5ton heat pumps, so that maybe 60-80 amps for that. Then everything else. I am not too worried about exceeding 200 amps, but 126 seems like cutting it close. I don't want to think about manual load shedding except during an outage. An alternative to whole house backup is to make my normal load panel the critical load panel and move the EV chargers (and maybe one heatpump) outside of that. Then the Solark has to supply way less to the load panel.

I am unclear on what MA/DPU defines as the "nameplate capacity". The 12k can invert 12kW of solar. But it can only export 9kW to grid. My guess is that they would say that is 12kW. Based on my previous two installs (no storage so it was easy), they don't care about the DC side, just AC, so you can go over 25kW DC panels, which I am considering.

That 9kW limitation to the grid on the 12k isn't great. So on good production days, I can only send 18kW to the grid, not 24kW. Not sure how much clipping that will be, but that only might be worth it to use three 8ks which can each do 8kW to the grid.

Bottom line is that 3 8ks is much more capable than 2 12ks. After the 30% federal tax credit it is only a $3200 difference so that is where I am leaning ATM.

-Mark

 

[Bkord]

My power company based my inverter on the ac output. Witch is 9k they did not care about the dc input. So I dump my batteries to the grid early in the morning and start charging them up around 10am. So I can use All 12k of my pv. 9 for grid and 3 to batteries. In a round about way I can send all 12k to the grid. Just not at the same time of day. I never send 9k to the power company. Because my house is always using something. My array is 12.4 and I have only seen 12k 3 times this year.
Can the 8k sol ark be stacked. I thought only the 12 and 15 could do that. I could be wrong. The name plate on my sol ark says 9k

 

[Danke]

Install just one 15k now, and another…

 

[robby]

You cannot stack the 8Ks.
2x12K would be a better option with a total pass through power of 30.24KW between the both of them.
Two eFLex maxes are a good match for this system.

 

[mcorner]

Argh, you are right, no stacking 8ks. So the only solution is to use two 12ks and either hope for the best or split the loads between critical and non critical. Without two ev chargers it probably will work fine.

A good first step might be to measure my total current with a sense or something.

 

[RV10flyer]

My 2 12k only maxed out once back in April at 125 kWh in one day with 20,640W array bringing in 21,000W. I doubt you'll get full output at any time north of 38 deg Lat. You need 4 12K's and 250kWh LFP. ?. About $200K.

 

[mcorner]

Yep, if I have a 25kw dc array and 18kw of inverter then it is a 1.4 ratio. That should only be around 2% loss overall (looked at a few graphs i found) and probably less in MA and even less if I have the battery discharge before peak. All great advice, thanks!

 

[Bkord]

Yep, if I have a 25kw dc array and 18kw of inverter then it is a 1.4 ratio. That should only be around 2% loss overall (looked at a few graphs i found) and probably less in MA and even less if I have the battery discharge before peak. All great advice, thanks!

I think sol ark recommends 13k pv for each 12k inverter. So 25 would get you close.