Efficiency issue or...????

[SHTF Power Anyway]

Our system includes 2 Sol-Ark 12kw's wired in parallel supported by 10 Fortress Eflex 5.4 kwh batteries in parallel for a total energy storage of 54 kwh. We've been working on this system over several months which included an upgrade of adding that 2nd Sol-Ark and 6 more batteries (a huge investment for us). We live in the PNW where the uptake has been HORRENDOUS for weeks now. We've returned the shop which was intended to be powered by this solar system back to the grid for the time being while we allow the system to recharge to a workable level. In that process, we decided to see just how much power we were losing to the equipment itself because we felt like there was no way we were going through the battery bank so quickly with the loads we had on it. My first day numbers were disturbing:

We started the day with 69% battery capacity (69% * 54kwh = 37kwh)
We had a relative decent day of uptake bringing in 18 kwh
The Sol-Ark efficiency is supposed to be 97.5% so my bankable kwh should have been 17.5 which would have filled my battery bank
There are losses within the batteries themselves as they show an efficiency of 98%. But at 98% efficiency, do I lose 2% for every battery I have in place? I'm not sure how to calculate this loss. Overall, I'm missing another 7kwh of my uptake from yesterday after accounting for the Sol-Ark's losses. To me, that number is HUGE when my uptake can be that or less in a single day. It's pretty frustrating.

Am I analyzing this correctly?

I'm not including info on my PV because I'm analyzing at the point of inverter/battery bank which tell me what my PV generation for the day was. Also, I don't think temperatures played any role as we had mid 40's or more all day. We haven't had any freezing lately and when we did, we had the system heated and the batteries well insulated and the thermometers showed no drops below 35F in the space.

 

[Lt.Dan]

I don't have enough time to read your whole post so forgive me if im not answering your question correctly, but don't forget the 97.5% efficiency is PEAK efficiency. During low loads or any load outside of that perfect efficiency range, the efficiency will change drastically.

 

[John Frum]

Our system includes 2 Sol-Ark 12kw's wired in parallel supported by 10 Fortress Eflex 5.4 kwh batteries in parallel for a total energy storage of 54 kwh. We've been working on this system over several months which included an upgrade of adding that 2nd Sol-Ark and 6 more batteries (a huge investment for us). We live in the PNW where the uptake has been HORRENDOUS for weeks now. We've returned the shop which was intended to be powered by this solar system back to the grid for the time being while we allow the system to recharge to a workable level. In that process, we decided to see just how much power we were losing to the equipment itself because we felt like there was no way we were going through the battery bank so quickly with the loads we had on it. My first day numbers were disturbing:

We started the day with 69% battery capacity (69% * 54kwh = 37kwh)
We had a relative decent day of uptake bringing in 18 kwh
The Sol-Ark efficiency is supposed to be 97.5% so my bankable kwh should have been 17.5 which would have filled my battery bank
There are losses within the batteries themselves as they show an efficiency of 98%. But at 98% efficiency, do I lose 2% for every battery I have in place? I'm not sure how to calculate this loss. Overall, I'm missing another 7kwh of my uptake from yesterday after accounting for the Sol-Ark's losses. To me, that number is HUGE when my uptake can be that or less in a single day. It's pretty frustrating.

Am I analyzing this correctly?

I'm not including info on my PV because I'm analyzing at the point of inverter/battery bank which tell me what my PV generation for the day was. Also, I don't think temperatures played any role as we had mid 40's or more all day. We haven't had any freezing lately and when we did, we had the system heated and the batteries well insulated and the thermometers showed no drops below 35F in the space.

Are you saying that 7 kwh out of 18 kwh went missing?

 

[SHTF Power Anyway]

Are you saying that you 7 kwh out of 18 kwh went missing?

Yep

 

[SHTF Power Anyway]

Are you saying that 7 kwh out of 18 kwh went missing?

I should clarify that I know some of this was battery losses but it doesn't seem reasonable to me at all.

 

[John Frum]

Yep

Please post pictures of your setup.
With that kind of loss I suspect something is bypassing a shunt or similar.

 

[John Frum]

I should clarify that I know some of this was battery losses but it doesn't seem reasonable to me at all.

LFP batteries are typically over 99% efficient.
Do you have an IR thermometer or camera to check for hot spots?

 

[John Frum]

Yep

61% efficiency end to end.
Something should be very very hot.

 

[John Frum]

I have a ceramic heater that draws ~1000 watts on the low setting.
Your daily losses are equivalent to 7 hours of running that heater.
It warms up my workspace nicely.

 

[SHTF Power Anyway]

My husband just looked through everything for any heat issues. The highest reading he got was 65F

 

[John Frum]

Your pictures show your harvest as 9.2 kwh and 1.9 kwh which is ~11.8 aggregate.
Where did you get the 18kwh figure from?

 

[SHTF Power Anyway]

Those numbers are from today. The 18kwh was yesterday's total uptake.

 

[John Frum]

From the AIO displays

solar in = 1520 watts
to battery = 1420 watts
93.421052632% efficiency

solar in = 620 watts
to battery = 590 watts
95.161290323% efficiency

These values are bang on what I would expect.

 

[John Frum]

Overall, I'm missing another 7kwh of my uptake from yesterday after accounting for the Sol-Ark's losses.

How are you determining that 7000 watt hours is missing?

 

[SenileOldGit]

Have you tested all of the battery cables with a clamp meter when the inverters are charging them, to check that the amps shown on the meter is as much as the inverters say they are sending to the batteries?

 

[niktak11]

You'll have around 3kWh of self consumption from those inverters per day too

 

[Nobodybusiness]

Our system includes 2 Sol-Ark 12kw's wired in parallel supported by 10 Fortress Eflex 5.4 kwh batteries in parallel for a total energy storage of 54 kwh. We've been working on this system over several months which included an upgrade of adding that 2nd Sol-Ark and 6 more batteries (a huge investment for us). We live in the PNW where the uptake has been HORRENDOUS for weeks now. We've returned the shop which was intended to be powered by this solar system back to the grid for the time being while we allow the system to recharge to a workable level. In that process, we decided to see just how much power we were losing to the equipment itself because we felt like there was no way we were going through the battery bank so quickly with the loads we had on it. My first day numbers were disturbing:

We started the day with 69% battery capacity (69% * 54kwh = 37kwh)
We had a relative decent day of uptake bringing in 18 kwh
The Sol-Ark efficiency is supposed to be 97.5% so my bankable kwh should have been 17.5 which would have filled my battery bank
There are losses within the batteries themselves as they show an efficiency of 98%. But at 98% efficiency, do I lose 2% for every battery I have in place? I'm not sure how to calculate this loss. Overall, I'm missing another 7kwh of my uptake from yesterday after accounting for the Sol-Ark's losses. To me, that number is HUGE when my uptake can be that or less in a single day. It's pretty frustrating.

Am I analyzing this correctly?

I'm not including info on my PV because I'm analyzing at the point of inverter/battery bank which tell me what my PV generation for the day was. Also, I don't think temperatures played any role as we had mid 40's or more all day. We haven't had any freezing lately and when we did, we had the system heated and the batteries well insulated and the thermometers showed no drops below 35F in the space.

I have same system but different batteries and I am getting 98.6% charge efficiency.

I’m sure some of the EEs on here can help you out.

You sure it’s not getting ate up by loads?

 

[John Frum]

OFF TOPIC:
@Nobodybusiness I just noticed the triple pole single throw breaker for the sol-ark to main dc busbar circuit.
How is it connected, is it one pole for negative and one pole for positive or something else?

 

[Nobodybusiness]

OFF TOPIC:
@Nobodybusiness I just noticed the triple pole single throw breaker for the sol-ark to main dc busbar circuit.
How is it connected, is it one pole for negative and one pole for positive or something else?

It’s a Triple ganged breaker for only the positive side.
The negative Busbar run directly to a board.

That’s the 12k. Not sure about the 15k.

I just had to replace mine recently.
Sol-Ak sent me one since under warranty still.

 

[John Frum]

It’s a Triple ganged breaker for only the positive side.

Interesting.
That is 750 amps aggregate.
I had wondered if they had used just 2 of the 3 poles which would be 500 amps aggregate.
Either way its out of spec high for 4/0 awg pure copper wire with insulation rated to 90C.

Thanks.