Wynand

[Wynand Solar]

My solar system consists of 24 X 330w panels, 2X 5kw Mecer inverters, 2 X MD Lithium 7.4 kwh batteries and MD Logger.

System operate very well except when batteries are fully charged during day the inverters shut off for about 30 seconds a few times.

That happens when i do not use much power.  I am in Cradock which get very hot.  It must be some setting.  I think the solar panels

still produce a lot of power and overloading happens.  Can someone  help me.  Already lost my camera monitor because of the resetting.

During the morning i use a lot of power and do not get the problem.  Always in the afternoon.  

[pilotfish]

Try lowering your bulk and float voltages on the batteries (speak to your supplier!).

So what is probably happening is the following;

• Your float bulk/float voltage is at max, triggering the BMS to block any further charge current,
• You have a high inverter load being carried by the PV panels,
• The load then drops (eg kettle shuts off),
• The MPPT takes a moment to respond to the lower load requirement and would normally dump this excess power into the battery bank - but cant
• P=VI, so with nowhere to send the amps, the voltage must climb
• Your inverter senses this dangerously high voltage and so shuts down rather than blowing up
• Then restarts because it is set to do so.

If you lower Bulk to about 52V and float to about 51.5V (speak to your supplier!!) you will find that your batteries are still reaching 100% SOC, but are still able to accept the momentary excess power referred to above.

Disclaimer - The above works with the batteries I use which is NOT the same as the batteries that you are using - so speak to your supplier!!! 

[pilotfish]

To simplify the above - ask your supplier what your 95% SOC voltage is (or check your battery literature), set bulk and float both to this voltage.

[Jaco De Jongh]

3 hours ago, Wynand Solar said:

2X 5kw Mecer inverters

Do you maybe have Solar power or software that came with these inverters, Those has a Log, just go to the Log and it should tell you if there is any alarms or specific reason that causes the shut down/reset.

3 hours ago, Wynand Solar said:

I think the solar panels

still produce a lot of power and overloading happens. 

The solar panels can only produce what is asked of it, so lets say your load is 100 watt, your solar panels will only produce 100 watt, and if you switch  on the kettle, the panels will produce more power and try to match the load. 

Does it show an alarm during this time?

[Wynand Solar]

Thank you.  I have adjust the bulk and float levels as suggested.  Will monitor and give you feedback.

By the way they were much higher than the suggestion.

[Dex_]

4 hours ago, Wynand Solar said:

Thank you.  I have adjust the bulk and float levels as suggested.  Will monitor and give you feedback.

By the way they were much higher than the suggestion.

as per @pilotfish i would check the manufacturer recommendations, I don't know your unit but I would expect your bulk charge to be higher like 53V+ so it is very possible yours was higher

[Wynand Solar]

It was higher.  I adjust the settings at the moment.  Would take a day or two to get the right settings.