Guru
Joined: 13/10/2014
Location: AustraliaPosts: 1858
| Posted: 02:08am 29 Jul 2024 |
Just to give you an idea of why and how I use these settings in my Nano Controller.
A Large LiFePO4 setup with 4 x 53v battery banks.
I have them set for Low Charge rate with a Max charge setting of 25A per Bank.
I usually charge to 90% SoC, evening + over night + early morning, before Solar consumption, typically results in the batteries at around 83% SoC, occasionally down to 72%.
During the mornings, this will often drop to 50% SoC when the Workshop is powered up and used, Solar HWS is sometimes switched across as well, and sometimes in the evening in cold winter cloudy days.
The lower max SoC, and higher SoC from overnight results in an average charge rate of around 3A to 10A per bank [ 12A to 40A ] this results in 90% SoC being reached at around 3pm, while still running OFF grid + charging + household + workshop loads, and running mostly on 4 or 5 Solar chargers and arrays - except with heavy workshop usage.
The only time the Inverter would switch off and cause the ATS to transfer all loads to the Mains supply would be if SoC went below 40%, it would normally happen at night, so the "restart timer" is set at two hours.
In the morning, Two hours after initial charging starts, there would normally be enough Solar to start the Inverter, and usually enough battery charge to even handle cloudy weather intermittent low solar periods by then.
In either case the Inverter can never be in a state of continually being switched between Inverter and Mains supplies by the ATS, because even 10 minutes of controller restart timing will not allow that to happen.
The same sort of conditions would apply when our Mains AC finally gets disconnected.
In winter and poor solar conditions, charge rate and SoC is increased, having the settings in the Controller makes it so simple to adjust the inverter for these changing charge conditions.
The charge rate and SoC are adjusted to get the maximum life from the LiFePO4 banks. They like charge + discharge cycling, and not sitting at a high SoC for hours, and especially when close to 100% SoC, even with a small tail current.
I also have true charge-discharge tracking and SoC monitoring, it can be used to override the restart timer if the need ever arises.
What must be kept in mind with full off grid systems, some of us build these ourselves because we don't want to rely on commercial equipment that we can't get parts for, or circuits or can't repair.
Finally it's not an exercise in right or wrong way to do something.
We make our own Solar chargers and inverters to be self sufficient, and like others, I have a lot of spare parts for any, and all repairs, and pre-built modules.
I will not build a system that requires an interconnect network of ANY kind unless I designed and built it - even then I would likely not use it because of the increasing critical parts shortage, transportation, supply chain, infrastructure and economic situations that are full of read flags and increase with each passing week.
If I'm not around, my Wife, family and friend must at least be able to operate the system, and someone with a bit of intelligence should be able to swap out a complete spare Power board or controller, or low voltage solar charger if needed, I make step by step videos and manuals for them.
Your outlook, location, situation and views my be completely different to mine, your Inverter, solar designs, installation and needs will also be completely different to mine.
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Edited 2024-07-30 08:16 by KeepIS