2x Sol-Ark 15K's + HomeGrid Stacks

[Tpilgeram]

After 1-1/2 years of planning I'm roughly a week and half into my new setup. 2x15Ks - 57.6 kWh of HomeGrid Stacks - 20.4 kW of REC's w/ Tigo TS4-A-O Optimizers and Cloud Connect Advanced (CCA) - Bypass/Transfer Switch - MicroAir Easystarts on my 3.5 & 4-ton AC units. Big house draws are pretty much all gas (other than the oven and my daughter's Nissan Leaf) so I have quite a bit of power to spare right now, but July & August should be close if my math holds out. So far this has handled everything I've thrown at it with zero compromises. There's actually a screen shot from this morning with me charging the batteries, the car, and exporting all at once. ? The only disappointment so far has been the lack of 600A charge limit from the Homegrids when they prominently advertise 300A for each stack. Most of the time the BMS is calling for 200-240A (total). Super conservative at <= 0.2C. That said, I've barely ever run into the charge limit and started exporting on PV. I was at 100% yesterday at 17:15, 79% at dawn this morning, and was topped back off and exporting by 10:40. ? Now, before anyone mentions it...yes this was an expensive endeavor that doesn't make a whole lot of sense if all you're after is ROI. That's not my focus. Feel free to ask any questions about the system/performance/behavior.

I have the exact same issue with my HomeGrid Stack’d. BMS limits to 20 amps per module nearly all the time. Your 2 sets of 6 gives you 240. I only have 4 modules and am limited to 80 amps charge by the BMS vs the 300 they promise. HomeGrid service has been absolutely useless at solving the issue. Very frustrating to be lied to about the battery capability. I can overage and use voltage manual mode to charge at the limits. I am also using a Sol-Ark 15k.

 

[2TrevorJ]

I have the exact same issue with my HomeGrid Stack’d. BMS limits to 20 amps per module nearly all the time. Your 2 sets of 6 gives you 240. I only have 4 modules and am limited to 80 amps charge by the BMS vs the 300 they promise. HomeGrid service has been absolutely useless at solving the issue. Very frustrating to be lied to about the battery capability. I can overage and use voltage manual mode to charge at the limits. I am also using a Sol-Ark 15k.

Are you running the latest firmware? I would also recommend you cycle them for a bit if you haven't already. Just run the house off them at night. I noticed mine became less conservative with cycles. The attached is yesterday's charge curve. Poor production day so I spent all day under 82% SOC but you can see it was calling for 600A charge all day.

Also keep in mind that below 17C, above 89% and below 41% you'll likely never see the BMS call for 300A per stack. I'm guessing that low battery temperature might be your issue there in Michigan.

 

[Tpilgeram]

Are you running the latest firmware? I would also recommend you cycle them for a bit if you haven't already. Just run the house off them at night. I noticed mine became less conservative with cycles. The attached is yesterday's charge curve. Poor production day so I spent all day under 82% SOC but you can see it was calling for 600A charge all day.

Also keep in mind that below 17C, above 89% and below 41% you'll likely never see the BMS call for 300A per stack. I'm guessing that low battery temperature might be your issue there in Michigan.

Thanks! Yes. I’ve let them cycle every night for the last 2 months. The HomeGrid service techs on the phone claim that the temps I was running (10C ish at the time) should not be causing the limit. I don’t believe them and asked for the curves, but they have not provided them yet.

 

[2TrevorJ]

Thanks! Yes. I’ve let them cycle every night for the last 2 months. The HomeGrid service techs on the phone claim that the temps I was running (10C ish at the time) should not be causing the limit. I don’t believe them and asked for the curves, but they have not provided them yet.

They provided the attached mid-Feb last year. SOC wise it doesn't jive with what I've recorded. Temp-wise it's close (although I've never been over 44C).

Not like I would ever see 1C. Hell, their highest stressed stacks (2 or 3 slabs) don't exceed 0.9C charging so I don't get why the documentation shows 1.0C.

 

[Tpilgeram]

They provided the attached mid-Feb last year. SOC wise it doesn't jive with what I've recorded. Temp-wise it's close (although I've never been over 44C).

Not like I would ever see 1C. Hell, their highest stressed stacks (2 or 3 slabs) don't exceed 0.9C charging so I don't get why the documentation shows 1.0C.

Good graph. Battery in the garage and not seeing 17 C batt temp here in Michigan until the end of a sunny day charge event when the SOC is too high for a faster charge anyway. You can see the charge current limit is always 80A which matches the .2C. Thanks.

 

[2TrevorJ]

Just hit 30 MWh!


The last 8 days have been bonkers. 765.1 kWh produced and 344.2 exported! 95.6 kWh on average per day.

 

[1201]

Just hit 30 MWh!

View attachment 198454
The last 8 days have been bonkers. 765.1 kWh produced and 344.2 exported! 95.6 kWh on average per day.

thats fantastic. congrats. what do you figure your payback time to be, on this system?

 

[2TrevorJ]

thats fantastic. congrats. what do you figure your payback time to be, on this system?

~14 years I'm betting at normal annual power cost inflation. By then it will likely be time for a replacement/upgrade and i probably won't get much of any "free" power out of it. As I said though...money was not my primary concern. Very happy with my setup!