Hi
i am new to this and need advise if possible
i have installed 1 x 280ah x16s battery bank and 2 x 304ah x 16s battery banks
10 PV panels at 405w each feeding through a growatt inverter
i have installed an ME3000sp and am after some thoughts on the best settings for this unit
i am charging in auto mode
these are my settings at the moment
DEFAULT BATTERY
BATT CAPACITY 888AH
DISCHARGE DEPTH 80%
MAX CHARGE 52A
OVER PROTECTION VOLTAGE 58.5
MAX CHARGE VOLTAGE 58.4
MAX DISCHARGE 52A
LOW VOLTAGE PROTECTION 42.5
MIN DISCHARGE VOLTAGE 46
EMPTY DISCHARGE VOLTAGE 44
FULLY CHARGED 55V
any advise would be helpful
Your settings seem OK.
Iād say that youāre going to hammer the battery with charging to 100% and discharging down to sub 7%. But itās your battery, so your choice.
Discussions on the best strategy have been running for years with the āget the max use and then replace itā or the āmake it last as long as possibleā camps arguing over which is best.
The only other question Iād ask is if your BMS is connected to your Sofar, and does the comms link work? Or have you set this in basically dumb battery mode?
I ask, as my batteries a LiFePO4 too, but ready made by Pylon, which has its own section in various version of the ME3000SP manual -
You need to tell the Sofar that itās got a Pylon connected, and still feed it these parameters, which are more conservative than the default for LiFEPO4.
Hi Lee
Thanks for the reply again
Could you please tell me what setting is making me charge to 7% as i definitely do not want to do this
I thought I would only go to 20%
Now you have said this I watched it go to 16 % the other day and honestly thought it would cut out at 20%
Please advise me if poss
Because I donāt want to go to 7%
I do not have the bms linked to the sofar
They are just balancing at the moment
I think itās the MIN DIS VOLTAGE where there inverter tries to stop the discharge.
46V is about 7% by my maths.
However, I may have been getting ahead of myself.
My settings have 47V (nearer 9%), but there is an 80% DOD setting, which is pulled from the Pylons BMS over an RS485 comms link, so the 47V is not so relevant.
Technically the chart says it should be 51.6V for 20% SOC.
However (isnāt there always!), it depends on the current being pulled at the time. A high current can make the voltage sag (drop) a long way, and when the current draw goes away, the voltage can bounce back. For example my batteries can be as low as 47.5V or as high as 48.3V when the BMS says the SOC is 20% and cuts off the power. A few minutes later the voltage recovers to nearly 50V.
So, I think, in summary, itās not clear cut. Running the Sofar with Lead Acid batteries and no BMS is a function of the Sofar. Running huge LiFePO4ās without a BMS connected to the Sofar may run your battery better/worse than with. I think setting the cutoff voltage a bit higher, say 48V assuming itās under a medium load may be your best bet. If youāre going to be monitoring the battery voltages into EmonCMS, youāll get a handle on how itās working and you can alway tweak the settings later.
Hi Lee
Thanks for the info
I did have the cut of set at 48v and should have left it there
as since a friend said thatās to high put it at 46v thatās when I noticed soc dropping lower
I also had the empty discharge voltage set at 46 and he advised 44
I think I will put these back to what they were
I am having economy 7 fitted soon so will be charging from the grid in winter and using the batteries during the day for power
Is this something you know about Lee
Thanks for your help again
Kind regards
Gary
Oh, yes. Iām on the Octopus Intelligent tariff (have been on Go Faster for 3 years before).
So I charge the battery during the winter, but during the summer the PV system mostly charges the battery.
You can get the Sofar itself to charge the battery overnight, but itās a little clunky. And uses the wifi adapter and the phone app. Iām not keen on my kit talking to random servers and getting random firmware updates. So my wifi adapter never got connected.
Instead, Iāve got a RPi1 connected to the Sofarās RS485 comms connector. The Pi runs some python that reads data out of the Sofar every minute (then posts them to EmonCMS) and can send commands to the Sofar. Back on my EmonCMS Pi2, I also run NodeRed (I know!), which watches the status of the inverter (the SOC mostly) and depending on the SOC/spare power, time etc, sends commands to the Sofar to switch to Auto mode, force charge or standby.
Depending on the time of year, say winter, it may force charge to 95% overnight (off-peak), then standby for a bit, then go back into auto when the on-peak starts. Over the summer, it checks for under 50% and force charges to 50% when off-peak (to make sure there is some power in case of a bad weather day). Iāve also tried using SolCast (for predicting next days solar) but itās not great. Also during summer it only PV charges the battery to 85% and puts it into standby. It then watches the solar input and house use to decide when to put the battery back into auto mode.
Iāve been meaning to migrate all this code to Home Assistant, but not had the time.
Thanks Lee for getting back
I like the sound of that
I was hoping as you say to charge off peak and run of the batteries during peak hours
When it gets nearer the time I might need a bit of pointing in the right direction if thatās ok
I am expecting to get another lot of batteries before winter so should have 60kw storage by then
I do not know a lot about the jk bms but was advised to put one on each set of batteries
Thanks for your help
Kind regards
Gary
We use a lot of electric during the day
Especially in the winter
So i bought more batteries to spread the load over 4 sets of batteries instead of major charging and discharging the hell out of 2 sets
Does that make sense
Kind regards
Gary
Hi Lee
I have economy 7 being fitted this week
I have an extra me3000sp sitting next to my usual me3000sp as a back up
My idea was to force charge the batteries during off peak hours if they need it
And use the batteries during the day in peak times
Is this the right way of thinking
If so please advise
Kind regards
Gary
Both connected to same battery pack? Or to two separate packs?
Going into the same pack may cause serious issues.
With two packs, you may get other issues like race conditions, of who discharges first, and one inverter trying to charge while the other is discharging. Try it by all means, but expect to be disappointed.
I know that setups like the Tesla Powerwalls can do this, but they have comms between them to decide whoās going first/etc.
With the huge batteries, I donāt see much point of doing it during the summer while thereās plenty of solar.
During the winter (less solar) definitely, I like I mentioned above.
Hi Lee
Thanks for replying
I was hoping to use them as two inverters on one busbar
Then getting 6kw of power from them
But I was told there might be issues
So I wanted the second unit just as an extra force charger in winter
Both charging on the same busbar as if 1 battery
Any ideas
I think your best bet would be to split the battery pack in two then to give each Sofar a pack.
Using the scheme above that may well work, as youāre managing what each inverter sees as the ātrueā state of things.
There is also this page I bookmarked a while ago - https://www.setfirelabs.com/green-energy/multiple-sofar-me3000sp-inverters-for-3-phase-setup
which may give more clues.
Hi Lee
Have wired this all up now
I have split the batteries into two packs as you suggested and a sofar unit on each pack
They are linked with an extra ct clamp so one unit is doing the main work and the other unit cuts in when i use over 3kw
They are on time of use now and are charging at night on economy 7
And discharging during the day
Its all working great now
Why so much storage?