Confused about Grid support battery charge priority

[srcorrecto]

My DC coupled system have about 7.9 kw pv for two schneider mppt 60-150 that generates about 6.5 kw ( 120 amps x 54.4 volts). I have a xw6848pro at fw 1.11 and a Gateway at fw 1.17. When i was in grid support-zero sell mode the system charges the battery to full 54.4 volts, no matter the GSV setting so at dark it started to supply my loads from the battery until hitting GSV. That was perfect operation.

My problem began when i started net-metering and modify selling to grid setting. I set it to 25 amps at 240 volts (5.76 kw) max sell. Since i am open loop i set GSV to 0.5 volts below mppt's float setting. It started selling right away. But, if i change the GSV for example to 52.8 volt from 54.2 v it just charge the battery until getting to GSV, not fully charging it. The mppts were in bulk mode all of this time. The system keeps on selling to grid almost everything produced but does not charge to full the battery. Is that the correct way for the system to respond. Thanks for any insight. !!!

 

[400bird]

It sounds like you want to sell excess solar after the battery is charged?
Pick the voltage that means your batteries are "fully charged" set your grid support voltage to exactly that voltage.

Then as the sun comes up, first the battery will be charged. Once the battery voltage raises to your "fully charged" and grid support voltage, the remaining solar production will be sold to the grid.

 

[srcorrecto]

Thanks for replying. Your first paragraph describes exactly how my system is working. Because of the current heat wave here the utility bill went up a little and my plan was to try to use battery power after the sun comes down and cannot do that by lowering the GSV as i could before with sell amps=0.

If i set for example GSV to 52.8 volts, as the sun comes up it starts to charge the battery but only until getting to the GSV and not to full, even if the mppts were in bulk mode al sun day. So i cannot use battery after dark because it is already at GSV whe the sun comes down

 

[DVD]

I agree with @400bird. What voltage means “fully charged” for you?
Set GSV to something just below that.

 

[srcorrecto]

Thanks for all replies. To clear things a little lets use SOC for a minute ok? If i set GSV to 99-100% SOC when the sun comes down there is no use of the battery to supply loads as it is already at GSV. That is how i have it now.

Second case: i set GSV to 60% SOC. when the sun comes up it starts to charge the battery but it stops at 60% SOC and does not charge to 100% even with the mppts in bulk mode, so i cannot use the battery when the sun comes down either. That is my dilemma. is it how it is suppose to work?

 

[DVD]

Sorry I’m uncertain now what you’re trying to do, so I’ll humbly bow out. Please keep updating.