Very happy 1st October to all. Oktober, die mooiste, mooiste maand. (CJ Langenhoven)

Setup:

2 x 100AH Li-PO batteries (48v)

6 x 550W panels

I want to use as little as possible utility.

Current Settings on my menu:

1: SUB & 14: SNU

I initially has #1 on Solar. So, the inverter changed over to solar as soon as it detects sunlight and changes back to utility when it is dark. The problem here is that it then uses utility to charge the battery to 95%. It then uses more electricity to get it full again than what I saved during the day by using solar & batteries. I also tried setting #49 where I set the time that utility must charge the batteries. I never could this to work.

Is there someone out here who can help me with optimal settings for this inverter and setyp. This inverter does not have the BMS that other inverters have where I can set it to be fully charged by 17:00 or something like that.

Thanks so long.

22 minutes ago, deonholt said:

Very happy 1st October to all. Oktober, die mooiste, mooiste maand. (CJ Langenhoven)

Setup:

2 x 100AH Li-PO batteries (48v)

6 x 550W panels

I want to use as little as possible utility.

Current Settings on my menu:

1: SUB & 14: SNU

I initially has #1 on Solar. So, the inverter changed over to solar as soon as it detects sunlight and changes back to utility when it is dark. The problem here is that it then uses utility to charge the battery to 95%. It then uses more electricity to get it full again than what I saved during the day by using solar & batteries. I also tried setting #49 where I set the time that utility must charge the batteries. I never could this to work.

Is there someone out here who can help me with optimal settings for this inverter and setyp. This inverter does not have the BMS that other inverters have where I can set it to be fully charged by 17:00 or something like that.

Thanks so long.

If don't want to use grid to charge the battery, change setting 14 to OSO (only solar)

@deonholt ,

I must admit, it's been 5 years since I last used a Voltronics based inverter, but from memory, the "priority" setting for what you want your system to do is "SBU" Solar, then Battery, and Utility lastly.

Then look at the "Switch to Utility/Grid"(when battery goes flat), as well as "Switch to Battery"(when battery is charged again) voltage setting for the battery. This may depend on the chemistry (NMC/LiPoFe)/composition(13-16cells)

Try and setup your inverter for SBU.

Maybe tell the forum your exact model of inverter, (photo of the label on the side of the inverter) so that those with more/better knowledge/experience can advise.

I have a MUST which i think is a clone of yours.

Set the cut off for the battery lower. Say 20% and it wont switch over to the grid. Whether you have it as SBU or SNU it does not matter really from my experience. But this assumes you have enough battery to last the night.

Otherwise do OSO as suggested. When it hits the cut off, it wont charge the batteries and just supply the load from grid. When the sun is out, it will switch back to solar when the battery has reached the soc setting to switch back to battery/solar that you have set.

Edited October 1, 2025Oct 1 by Denns

12 minutes ago, Denns said:

I have a MUST which i think is a clone of yours.

Set the cut off for the battery lower. Say 20% and it wont switch over to the grid. Whether you have it as SBU or SNU it does not matter really from my experience. But this assumes you have enough battery to last the night.

Otherwise do OSO as suggested. When it hits the cut off, it wont charge the batteries and just supply the load from grid. When the sun is out, it will switch back to solar when the battery has reached the soc setting to switch back to battery/solar that you have set.

Thanks for the reply. No, unfortunately not enough to last through the night. Thanks for confirming OSO. Makes sence. Didn't think about it like this.

28 minutes ago, deonholt said:

Thanks for the reply. No, unfortunately not enough to last through the night. Thanks for confirming OSO. Makes sence. Didn't think about it like this.

In my case I run my system on SBU, also my battery does not last through the night, I have my voltage setting (12) set to switch over to grid once SOC gets to 20%. so, I make sure that every day I at least use about 80% of my battery.

6 minutes ago, Antonio de Sa said:

In my case I run my system on SBU, also my battery does not last through the night, I have my voltage setting (12) set to switch over to grid once SOC gets to 20%. so, I make sure that every day I at least use about 80% of my battery.

Would you not save by having it on OSO? Because on SBU it will just drain to 20% and then switch over to the grid to supply the load and charge the battery again so your net gain is zero. Whereas on OSO it would just switch over to grid and leave the battery at 20% till day break. In which your grid only supplies from the time the battery went dead to sunrise.

Edited October 1, 2025Oct 1 by Denns

@Denns That is exactly how I run my system, setting 14 is on OSO, setting 12 (switch over to Grid) set at 51 V that is +_ 25% of my battery SOC. One has to cater for the inverter "no load loss" in my case two inverters is +_ 1,8 Amps from the battery. I'm at home, depending on Wheater conditions, I will change settings when need. Also, I have a custom-made monitoring system where I can see basically everything on my system. as an example, the last two days.

Edited October 1, 2025Oct 1 by Antonio de Sa

18 hours ago, Denns said:

Would you not save by having it on OSO? Because on SBU it will just drain to 20% and then switch over to the grid to supply the load and charge the battery again so your net gain is zero. Whereas on OSO it would just switch over to grid and leave the battery at 20% till day break. In which your grid only supplies from the time the battery went dead to sunrise.

Good morning. Based on my question and all the replies, this is what I currently have:

#1 : SOL
#12 : 25%
#13 : 95%
#14 : OSO

Battery currently (08:53) at 78% and also uses UTIL to charge.

Is there something else or are these settings wrong? I don't want to use AC during the day. I can change settings remotely should I need to.

Thanks for your help & advice.

3 hours ago, deonholt said:

Good morning. Based on my question and all the replies, this is what I currently have:

#1 : SOL
#12 : 25%
#13 : 95%
#14 : OSO

Battery currently (08:53) at 78% and also uses UTIL to charge.

Is there something else or are these settings wrong? I don't want to use AC during the day. I can change settings remotely should I need to.

Thanks for your help & advice.

Those are basically it. My question is it charging the batteries still from utility or is it supplying load with utility but still only charging from solar?

That will happen because the inverter will wait for the battery SOC to reach 95% before it switches back to supplying your load with solar and battery. Because I have GEL batteries the inverter uses voltage to determine SOC. So what it would do is if it hit the battery cut off and switch to grid voltage, it would supply load from grid.

If the battery voltage reached the second setting as the solar was on for enough time to charge them, then it would switch back to supplying my load from solar and battery. The grid is completely left out.

If you lower the 95 to say 35 as a test tomorrow, it should switch back to battery and solar once the batteries reach that SOC. You can decide at what SOC you want it to be, but at the moment, it will wait for 95 before the inverter completely supplies from solar and battery alone.

Edited October 2, 2025Oct 2 by Denns

2 minutes ago, Denns said:

I had a look and the following were related to the charging behavior:

01: Output priority - SBU or SOL

05: Solar supply priority - BLU or LBU

10: Charger source priority - OSO

Those are basically it. My question is it charging the batteries still from utility or is it supplying load with utility but still only charging from solar?

That will happen because the inverter will wait for the battery SOC to reach 95% before it switches back to supplying your load with solar and battery. Because I have GEL batteries the inverter uses voltage to determine SOC. So what it would do is if it hit the battery cut off and switch to grid voltage, it would supply load from grid.

If the battery voltage reached the second setting as the solar was on for enough time to charge them, then it would switch back to supplying my load from solar and battery. The grid is completely left out.

If you lower the 95 to say 35 as a test tomorrow, it should switch back to battery and solar once the batteries reach that SOC. You can decide at what SOC you want it to be, but at the moment, it will wait for 95 before the inverter completely supplies from solar and battery alone.

Strange to see that it charges from UTIL in the morning if OSO is selected. As indicated may be the UTIL is just powering the load.

3 hours ago, Denns said:

Those are basically it. My question is it charging the batteries still from utility or is it supplying load with utility but still only charging from solar?

That will happen because the inverter will wait for the battery SOC to reach 95% before it switches back to supplying your load with solar and battery. Because I have GEL batteries the inverter uses voltage to determine SOC. So what it would do is if it hit the battery cut off and switch to grid voltage, it would supply load from grid.

If the battery voltage reached the second setting as the solar was on for enough time to charge them, then it would switch back to supplying my load from solar and battery. The grid is completely left out.

If you lower the 95 to say 35 as a test tomorrow, it should switch back to battery and solar once the batteries reach that SOC. You can decide at what SOC you want it to be, but at the moment, it will wait for 95 before the inverter completely supplies from solar and battery alone.

Ahh, ok, thanks. I will change accordingly and get back to you.

17 hours ago, Denns said:

Those are basically it. My question is it charging the batteries still from utility or is it supplying load with utility but still only charging from solar?

That will happen because the inverter will wait for the battery SOC to reach 95% before it switches back to supplying your load with solar and battery. Because I have GEL batteries the inverter uses voltage to determine SOC. So what it would do is if it hit the battery cut off and switch to grid voltage, it would supply load from grid.

If the battery voltage reached the second setting as the solar was on for enough time to charge them, then it would switch back to supplying my load from solar and battery. The grid is completely left out.

If you lower the 95 to say 35 as a test tomorrow, it should switch back to battery and solar once the batteries reach that SOC. You can decide at what SOC you want it to be, but at the moment, it will wait for 95 before the inverter completely supplies from solar and battery alone.

Thank you. Your suggestion to lower the 95 worked perfect. Thanks.