Greetings - I have an Axpert 5kw MKS with a 3.5kw USB 3000 pylontech battery and Solar array of 3kw. Problem is that during the day (sunshine galore) the system cuts the solar PV out and draws from the battery. I am of the opinion that if there is ample sunshine then the PV should support the battery and load. 01 is on SOL setting. In the morning it starts off with solar PV supporting the load and charging the battery........around 11:00 the solar PV graphic is there but idle. Please help.

Edited March 6, 20205 yr by Indres
A mistake on my part.

17 hours ago, Indres said:

around 11:00 the solar PV graphic is there but idle.

This sounds like a PV "freeze"; others have experienced PV "dips". There is a long discussion on it here and elsewhere.

But first: is it possible that you have too high a PV voltage, perhaps from 3S of 72-cell panels? PV power will derate above 130 V, and is down to zero power at 145 W.

And second: is your float voltage setting (setting 27) lower than your bulk/absorb voltage (setting 26)? If so, when the battery is declared fully charged (it may not be, due to the premature float issue), then the charge current will be zero for a few minutes (up to about 10 minutes with light loads). But then it should keep charging to maintain the battery at the float voltage setting.

So third: what is the middle ("charge") LED doing when this happens? Is it off, solid on, or flashing?

My apologies for barging in like this.

I had a similar problem with a Mecer Axpert MKS 5K 5000VA inverter last year, but managed to overcome it by playing around with the different settings to finally keep the PV panels engaged.

On Saturday, after using the electric lawnmower for about half an hour during the morning and a tumble dryer during the afternoon for about half an hour, the PV graphic on the LCD screen was no longer visible late Saturday afternoon.

The SOL mode and Utl mode now seems to be similar. Sbu mode still draws power from the battery. SOL and Utl modes both charge the battery. Utility power carries the load. No power from the PV panels.

Thanks in advance for any suggestions on what the problem could be?

On 2020/03/07 at 11:09 AM, Coulomb said:

This sounds like a PV "freeze"; others have experienced PV "dips". There is a long discussion on it here and elsewhere.

But first: is it possible that you have too high a PV voltage, perhaps from 3S of 72-cell panels? PV power will derate above 130 V, and is down to zero power at 145 W.

And second: is your float voltage setting (setting 27) lower than your bulk/absorb voltage (setting 26)? If so, when the battery is declared fully charged (it may not be, due to the premature float issue), then the charge current will be zero for a few minutes (up to about 10 minutes with light loads). But then it should keep charging to maintain the battery at the float voltage setting.

So third: what is the middle ("charge") LED doing when this happens? Is it off, solid on, or flashing?

Thanks Coulomb for the response......This is a PV max open voltage of 115V system. The panels deliver max 90V so there is no concern there. But having read similar complaints on local forums....it seems like we have a bad batch of MKS 5kw in South Africa. All points to a firmware problem. Just to answer .... the LED is solid and SOL is the prefered source. I will follow up on setting 27. But the  biggest concern is that even if it switches from Solar .... it shoud go to mains and not battery thus draining the battery until the sun goes down and then go onto mains.

1 hour ago, Indres said:

SOL is the prefered source.

I assume you mean that the OUTPUT source priority is SOL (as opposed to the CHARGE source priority being OSO).

1 hour ago, Indres said:

But the  biggest concern is that even if it switches from Solar .... it shoud go to mains and not battery thus draining the battery until the sun goes down and then go onto mains.

It doesn't "switch from solar"; solar and battery power are always blended.

But when it switches to line mode (AC-in powers loads) depends on settings 12 and 29. From the manual for Setting 01 (output source priority) = SOL:

"Utility provides power to the loads only when any one condition applies:

– Solar energy is not available

– Battery voltage drops to either low-level warning voltage or the setting point in program 12."

The low-level warning voltage referred to is undocumented, but in unpatched firmware is 2.0 V above setting 29 (low DC cutoff voltage).

To keep the battery from being discharged significantly during the day, you would want setting 12 to be relatively high.

So my supplemental question is: what are the values of settings 12 and 13 (back to grid, and back to battery voltages respectively)?

Edited March 9, 20205 yr by Coulomb

On ‎2020‎/‎03‎/‎09 at 9:53 AM, Gerswan said:

My apologies for barging in like this.

I had a similar problem with a Mecer Axpert MKS 5K 5000VA inverter last year, but managed to overcome it by playing around with the different settings to finally keep the PV panels engaged.

On Saturday, after using the electric lawnmower for about half an hour during the morning and a tumble dryer during the afternoon for about half an hour, the PV graphic on the LCD screen was no longer visible late Saturday afternoon.

The SOL mode and Utl mode now seems to be similar. Sbu mode still draws power from the battery. SOL and Utl modes both charge the battery. Utility power carries the load. No power from the PV panels.

Thanks in advance for any suggestions on what the problem could be?

Please allow me to report that my problem was solved by a most descent human being, Theo form Just Solar in Vereeniging.

He stopped by today, replaced two blown fuses, rewired the DB installed by the original “installers” and supplied a correct fuse for this DB. Charging me only for the parts.

If only I had been aware of Just Solar a year ago when I allowed the original “installers” to do the job . . .