I get overload warnings all the time on L1.
I know i can switch them off but i like to know where they are coming from.
System:
MP II
DESS
Solar connected to ups out.
On grid
The load on the system is minimal and no big machines starting.
Max input for L1 is set to 20 ampere.
I have been looking for an answer but can not find anything wrong. Batteries are full, and the connections are stable.
Anyone advice?
Hi, what inverter and battery do you have?
A bit more detail always helps.
There can be various causes.
Multiplus 48/5000/70
Cerbo
Batteries are 2x180 Ah in parallel with jk bmses
The load on the system is never more then 500 watt during the day.
Max PV is ~3000 watts
What else would you like to know?
Causes can be a number of things.
They are often a result of a battery/BMS, sometimes related to load/grid fluctuations.
DIY batteries are more prone to this.
It can also be a result of a weak grid. ESS/LOM detection can play a part.
I see them myself, not all that often but it happens, and it is grid related in my case.
It was more common on old firmware, but the current versions address the spurious occurrences.
I disabled warnings in the end, it was a minor event and the system was otherwise healthy and a weak grid wasnât about to change.
Ah, ok.
I have had all kind of grid problems lately.
Sometimes the MP makes a very loud humming sound for a second and changes its leds. When this happens, lights flicker in my house.
I think it has something to do with frequency because thatâs how it sounded in my working days in transformers and stuf.
The weird thing is that it does not seem to happen when i unload the ess client.
ESS forces a sync with the grid, and uses LOM detection which relies on trying to shift the frequency to work, so it makes sense.
You can try disable LOM as a test, but this is required for safety and regulatory compliance.
It is helpful to help confirm the source though.
1 Like
Thank you for your clear answer.
I have no problems not being completely compliand. I had to raise the maximum acceptable grid voltages from 253 to 267 volt to keep the multi running on grid. I have sometimes even higher voltages here, but in order to protect my devices, i have chosen to let multi disconnect from the grid if it goes even higher.
One question: is there a chance that i damage my mp when i disable lom?
And, even more important: will mp still be able to signal grid loss and stop sending power to grid?
I have a lot of power failures lately and donât want to electrocute a technician 
With LOM off there is a chance that is remains energised on the input for a period longer than normal.
It is considered âless safeâ
I am sure you have read a bit on it.
Alex has given you some good reading material.
No, it wonât damage your multi.
But always, safety first.
If you donât need all the benefits of ESS, rather run without it if stability is better.
Thank you both.
You have realy pointed me in the right direction.
Testing this will take a while. Especially because this system is in âproductionâ providing the house eith power and can not be switches off snd on as i like.
But thanks realy apriciate it.
I have now set the LOM to disabled.
Lets wait and see.
Maybe related problem:
I have also the problem that some times (mostly at night) my multiplus makes the sound as you can hear in this link: Multiplus II - Inconsistent sound and energy | DIY Solar Power Forum
Sounds very unhealthy.
My problem seems to be exactly what his problem is as far as i can tell.
When this happens lights flicker bigtime and the multi make a hell of a noise. I have the feeling it has something to do with grid herz, because if i switch off the grid then all returns to normal immediatly. Could this LOM change help with this to maybe?
Not likely.
If it is grid load and instabilty because of that, that makes sense.
Are the tree branches tickling the power lines at all near you?
Using ESS will change the behaviour as grid impededance (and harmonic noise particularly if you have alot of inverters your area, i know certian brands of inverters inject alot of noise ) becomes a larger factor in how it runs.
Are the tree branches tickling the power lines at all near you?
No, we donât have these any more in the Netherlands.
I am however at the end of a long grid line. In the middle of nowhere. Every big farm around me has a lot of PV. Voltage often goos up to 263 volt (at witch point i have set the MP to disconnect from grid to protect my electronics) and sometimes as low as low as 186. We do have 1 fase (the one i am on obviously) that has given problems at multiple times.
Could you think of any other reason why my MP is behaving as shown in the picture in the link? If it cannot be solved i will have no other choice than to start thinking of changing to another system. But i am not at that point yet. Or maybe forget about ESS completely, witch would realy suck because i have set up the system to do this. That would be an enourmous waste of money. Thats way i need to solve this so badly.
It will most likely be fluctuations and impedance in the grid.
My home install used to be on the end of a long line with (quite a few) joins in it. We had a hard time for a while.
since we donât have a grid code per say we could close up voltage tolerances and that helped alot.
Also disconnected from grid during the times of day when we knew there would more likely be problems. Other thing to have checked by the power company is the neutral connection on the lines. We have seen corrosion issues causing weirdness as well.
The other way we deal with bad grid is actually have one inverter inverting and another that conditional connects when needed to charge.
(There are a few videos out there like your link.)
we could close up voltage tolerances and that helped alot.
What do you mean by this?
I could disconnect from the grid at night. It seems to happen mostly at night. But how to automate that.
I have been thinking about a second MP for charging, but disconnecting the âmainâ mp from the grid permanently would effectively disable ess.
Do you feedback to grid?
Yes, i plan on using dynamic ess. Iâve been testing with it, and I know it was ok. Had set the batterys to âkeep chargedâ until my new grid dynamic contract starts in May. Then this sh*t started happening. It started after i had a gridfail. After that nothing but troubles with the weird sounds like in the clip.
A fault?
It is possible the repair has affected you negatively.
Are you able to ask for a phase switch?
Yes, one fase had a short to ground they said to me. They installed a MSN.
Google says: âA medium-voltage network switching device or an automatic recloser. These devices are used in the electricity grid to: Automatically restore the power connection after a temporary fault (for example due to a lightning strike or a short circuit caused by branches on the lines). Locate faults better by recording where and when the interruption occurs.â.
ChatGpt says that this device can also intruduce a temporary shift in fase. Somehow it helps them to find the exact location of the fault.
I had to keep the MP disconnected from the grid for 2 days and run on pv and battey.
Then they removed the device and it was ok again i thought, only to find out that it now it happens a lot less, but still it happens.
Am not shure that this is the reason of my problems but there seems to be a logic in this.
Asking to switch me to another fase is good advice. I think they will not do it, but there is no harm in asking. Very good idea.