C rate us based off the amp hour size of the pack.
65kWh would be 1300 Ah and 35kW of panels can output 800A so, it would be a max rate of .625 C I think...
Still quite fast...
Limit current to each battery string in a system with multiple parallel batteries.
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65kWh would be 1300 Ah and 35kW of panels can output 800A so, it would be a max rate of .625 C I think...
Still quite fast...
SupraSPL
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Looking at your diagram, 7kW solar with 1 or 2 28kWh batteries, that works well. And if you scale up those panels x 4 but also scale up the batteries x 4 you maintain a good ratio.
I looked up that REC BMS and from what I can tell it's 120 amp maximum for charging but 250A discharging? I wonder if it's adjustable to allow up to 250A coming in? Either way, if you used let's say a 200A BMS, that is 11kW that you could take in, per battery. 4 batteries capable of 44kW. And if your cells were good quality and all from the same batch, they would share the current very well and you could go really big on the panels.
I looked up that REC BMS and from what I can tell it's 120 amp maximum for charging but 250A discharging? I wonder if it's adjustable to allow up to 250A coming in? Either way, if you used let's say a 200A BMS, that is 11kW that you could take in, per battery. 4 batteries capable of 44kW. And if your cells were good quality and all from the same batch, they would share the current very well and you could go really big on the panels.
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Do plan to use different BMS to match the needed Amps. Now i just need to decide if really going with this (good that it should work) or the hybrid inverter should be less headache.
SupraSPL
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Ah gotcha, considering selling the excess to the grid? 80-90% of systems are grid tie only but fwiw I figure having a sizeable battery on hand could come in extremely handy in the event the grid goes down short term, long term or becomes unstable.
timselectric
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Not in this forum.
People come here to fix that mistake. lol
PreppenWolf
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If you really wanted over amp protection beyond the BMS, you could put individual T class fuses or DC breakers on each bank.
If it were me and I had such a large array with that small of a battery bank, I'd just raise the min voltage cutoff to 51V. This prevents draining the battery and somewhat limits inrush without sacrificing too much storage space.
A 36kWh array should really have a 200-300kwH battery.
I have a 15kW array on a 105kWh bank. I currently have only 93 battery cycle equivalents in 16 months of operation.
If it were me and I had such a large array with that small of a battery bank, I'd just raise the min voltage cutoff to 51V. This prevents draining the battery and somewhat limits inrush without sacrificing too much storage space.
A 36kWh array should really have a 200-300kwH battery.
I have a 15kW array on a 105kWh bank. I currently have only 93 battery cycle equivalents in 16 months of operation.
No, it's fully off grid and there is some sizable load. Mentioned hybrid just because I saw some with multiple PV inputs, quite high battery output... anyway, still to investigate.
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The premise of my question is that the imbalance is in the category "normal operation", not the "faults" category. For the faults I mentioned BMS is ok.
As others suggested, I can assume that any large imbalance, that could run 300+Amps into one battery, is in the "faults" category.
I also see my battery might be a bit smaller based on all the replies. Likely to add the 5th string to begin with and test how it works.
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