Growatt STP3000TL LVM-48P...Panels cranking out joules...battery reaches set point...solar charger stops charging...but

[JLBinTN]

the inverter starts pulling from the battery to power loads vs using ample solar power. I waited an hour to see if this situation would rectify itself, but it never did. Any suggestions? Which Growatt settings control this behavior?

 

[Solargrow]

I am having this same issue. I haven't solved it yet and it's super frustrating. I don't think it's a settings issue. It might be a firmware issue. You can contact Growatt America and they'll send you the info to do a firmware update. I haven't done my update yet. I'm scared...

 

[DThames]

the inverter starts pulling from the battery to power loads vs using ample solar power. I waited an hour to see if this situation would rectify itself, but it never did. Any suggestions? Which Growatt settings control this behavior?

If this inverter is the type that requires a battery, then all of the power will come from the battery. The battery should be charging at the same time, if the settings are correct.

 

[Solargrow]

If this inverter is the type that requires a battery, then all of the power will come from the battery. The battery should be charging at the same time, if the settings are correct.

These inverters are supposed to be able to use solar to power loads as first priority, while charging the battery with secondary solar, then saving the fully charged battery until solar runs down. The whole point in having batteries is to power loads without the sun, but we can't do that if the batteries get drained during the day

 

[SignatureSolarAdam]

Have you tried to turn the inverter off, then back on when the batteries get charged? This can help in sorting out a potential fix.

 

[DThames]

These inverters are supposed to be able to use solar to power loads as first priority, while charging the battery with secondary solar, then saving the fully charged battery until solar runs down. The whole point in having batteries is to power loads without the sun, but we can't do that if the batteries get drained during the day

I have a couple of the 3000w Growatts in split phase configuration. The chargers will try to hold the batteries at Float, after holding them at the boost voltage for the selected period. Does it drain the battery below the float voltage even though solar is available? Not saying this is ideal, just what I have been seeing.

 

[DThames]

I am having this same issue. I haven't solved it yet and it's super frustrating. I don't think it's a settings issue. It might be a firmware issue. You can contact Growatt America and they'll send you the info to do a firmware update. I haven't done my update yet. I'm scared...

What was your conversation with Growatt regarding the firmware? Did they say, "Oh yes version xyz has an issue"?

 

[Solargrow]

What was your conversation with Growatt regarding the firmware? Did they say, "Oh yes version xyz has an issue"?

I have a couple of the 3000w Growatts in split phase configuration. The chargers will try to hold the batteries at Float, after holding them at the boost voltage for the selected period. Does it drain the battery below the float voltage even though solar is available? Not saying this is ideal, just what I have been seeing.

I have the same setup as you describe with the two 3000s in split but they both have to be reset every morning to get them to detect the panels and then one of them starts using the battery once it's charged. It's extremely annoying. I decided to try going single phase thinking maybe the change in the way they communicate would help but it just does the same thing.
When I spoke to Signature Solar they were stumped but Alex told me they had been hearing about this issue. He said I could try the firmware update but most people he's spoken to hadn't had much luck with the 3000 models.
When I emailed Growatt they responded saying simply "Please use the link below to update the inverter firmware to fix the issue."
I was hoping I could fiddle out the problem with the settings but it's looking like I might have to bite the bullet and try the update pretty soon.

 

[DThames]

Just sharing an observation.....My split phase setup, when the battery is at Float one of the chargers will back off to zero or near zero watts. In this example say that leg1 is not charging and leg2 is charging at 400w to maintain the load and the battery at float. If I add load to leg1, leg1 charger does nothing but leg2 charger picks up the load and charges more to maintain float. So leg1 is running off the battery and not charging and leg2 is using solar to maintain float voltage.

 

[stienman]

This is known feature of Growatt inverters, and in fact many inverters, when you choose the lithium battery setting without battery communications.

The ideal charging profile of lithium without feedback does not permit float charging. So it's common in these profiles to stop charging completely, and start discharging until it goes below the trigger voltage to start bulk charging again.

Most users frustrated with this decision choose the user lead acid battery profile instead, and set the voltages to conservative values to prevent overcharging. The user lead acid profile does permit float charging, so rather than turning off charging, it reduces charging current to maintain the float voltage.

The ideal solution is to use batteries that communicate with the inverter, and tell it how many amps they can accept for charging - the inverter MPPT will then operate to provide current to the batteries and the AC inverter, and you'll have the desired outcome.

If you don't have batteries with a compatible communications protocol, then many users have chosen to use the lead acid charging profile. The downside is that it will continue to charge the batteries once they've reached their "float" voltage, and that's not the best way to handle lithium batteries. If you set the float voltage to a conservative value and turn off equalization, though, there are few other downsides, and the main downside isn't as harmful to the batteries as it might otherwise be.

Growatt and their suppliers will not support this usage, however, and if you intend to maintain your warranty then you will have to live with the consequences of that charging profile.

Another option is to buy a separate MPPT charger and charge your batteries through that, allowing the growatt to pull as needed for AC, and the external MPPT to charge as needed according to the power input and the battery voltage. This effectively bypasses the inverter's MPPT charger and its safe, but inefficient, user lithium charging profile.

 

[DThames]

This is known feature of Growatt inverters, and in fact many inverters, when you choose the lithium battery setting without battery communications.

The ideal charging profile of lithium without feedback does not permit float charging. So it's common in these profiles to stop charging completely, and start discharging until it goes below the trigger voltage to start bulk charging again.

Most users frustrated with this decision choose the user lead acid battery profile instead, and set the voltages to conservative values to prevent overcharging. The user lead acid profile does permit float charging, so rather than turning off charging, it reduces charging current to maintain the float voltage.

The ideal solution is to use batteries that communicate with the inverter, and tell it how many amps they can accept for charging - the inverter MPPT will then operate to provide current to the batteries and the AC inverter, and you'll have the desired outcome.

If you don't have batteries with a compatible communications protocol, then many users have chosen to use the lead acid charging profile. The downside is that it will continue to charge the batteries once they've reached their "float" voltage, and that's not the best way to handle lithium batteries. If you set the float voltage to a conservative value and turn off equalization, though, there are few other downsides, and the main downside isn't as harmful to the batteries as it might otherwise be.

Growatt and their suppliers will not support this usage, however, and if you intend to maintain your warranty then you will have to live with the consequences of that charging profile.

Another option is to buy a separate MPPT charger and charge your batteries through that, allowing the growatt to pull as needed for AC, and the external MPPT to charge as needed according to the power input and the battery voltage. This effectively bypasses the inverter's MPPT charger and its safe, but inefficient, user lithium charging profile.

 

[stienman]

View attachment 94269

Exactly. If you choose US2 you will have this issue. If you choose USE then you will find that the MPPT stays on even once the battery reaches its set point. But it is the incorrect profile for lithium. If you aren't expert at understanding the charging chemistry then you might have a bad day at some point in the future.

 

[DThames]

Exactly. If you choose US2 you will have this issue. If you choose USE then you will find that the MPPT stays on even once the battery reaches its set point. But it is the incorrect profile for lithium. If you aren't expert at understanding the charging chemistry then you might have a bad day at some point in the future.

I have mine set on US2 and it will maintain a float voltage. However, with two chargers connected to the same battery, it is common that one will back off to zero watts (after boost duration is reached) because it takes zero watts to maintain float voltage, when the other charger is holding the float voltage. That is not really a problem but the leg that is off is pulling from the battery while the other leg is charging the battery to make up for that load.

 

[Solargrow]

This is known feature of Growatt inverters, and in fact many inverters, when you choose the lithium battery setting without battery communications.

The ideal charging profile of lithium without feedback does not permit float charging. So it's common in these profiles to stop charging completely, and start discharging until it goes below the trigger voltage to start bulk charging again.

Most users frustrated with this decision choose the user lead acid battery profile instead, and set the voltages to conservative values to prevent overcharging. The user lead acid profile does permit float charging, so rather than turning off charging, it reduces charging current to maintain the float voltage.

The ideal solution is to use batteries that communicate with the inverter, and tell it how many amps they can accept for charging - the inverter MPPT will then operate to provide current to the batteries and the AC inverter, and you'll have the desired outcome.

If you don't have batteries with a compatible communications protocol, then many users have chosen to use the lead acid charging profile. The downside is that it will continue to charge the batteries once they've reached their "float" voltage, and that's not the best way to handle lithium batteries. If you set the float voltage to a conservative value and turn off equalization, though, there are few other downsides, and the main downside isn't as harmful to the batteries as it might otherwise be.

Growatt and their suppliers will not support this usage, however, and if you intend to maintain your warranty then you will have to live with the consequences of that charging profile.

Another option is to buy a separate MPPT charger and charge your batteries through that, allowing the growatt to pull as needed for AC, and the external MPPT to charge as needed according to the power input and the battery voltage. This effectively bypasses the inverter's MPPT charger and its safe, but inefficient, user lithium charging profile.

Yes, I've seen people discuss this as a possible resolution for the issue. I saw someone mentioned in another thread that switching to USE allowed them to set #19 & 20 at different levels and they set #20 at .5v less than #19, which seemed to work for them.
I tried it once before but it got worse. I probably did something wrong so I'm going to try again today. If I did that, what would my settings look like with a 48v battery? Specifically settings 12, 13, 19, 20 & 21?
Thanks again.

 

[JLBinTN]

I am having this same issue. I haven't solved it yet and it's super frustrating. I don't think it's a settings issue. It might be a firmware issue. You can contact Growatt America and they'll send you the info to do a firmware update. I haven't done my update yet. I'm scared...

Using USE vs US2 helps in that it stops the inverter from switching off solar for loads once the battery hits its set point and pulling solely from the battery. I still haven't found the correct voltage settings for 19 and 20 yet however. If they're too low, the solar charger starts backing off on the current to the battery too soon. Too high, and the battery charges all the way up to 100%. My goal here is to maximize solar output as well as maximize battery longevity (i.e. minimal use, charge within optimal parameters).

 

[stienman]

what would my settings look like with a 48v battery? Specifically settings 12, 13, 19, 20 & 21?

I don't feel comfortable making recommendations as each setup is different enough that there's no single answer.

My settings are very, very conservative because 1/3 of my battery capacity is from used cells nearly 15 years old, and they are poorly matched (capacity tested individually, then each paired with another so the combined capacity is +/- 1AH of every other pair - not taking into account internal resistance or other characteristics), and the other 2/3 doesn't have a BMS installed yet.

Still, while I can't recommend any specific settings, if you'd like to see what I'm running with let me know and I'll pull the current values off tonight and copy them here.

 

[Sunshine22]

I've been reading this forum regarding the Growatt issue of stopping solar after the battery has reached full charge. I have a couple questions. Below is what I'm using:
SPF 3000TL LVM-ES 3KW
USE2
Bulk 57.5V #19
Float 55V #20
DC Cutoff 46V #21
Batteries - 4 x Zoom 12.8v 200ah LiFePO4 in series
No Utility
4000 watts solar
Priority is set to SOL

I have not connected the inverter to a computer, so my questions and observations are based on the Growatt's display. What program do you guys recommend to monitor the details?

Scenario: The "Charge" light is solid (no charging) and the battery is at 54.8 volts or so with no load. During daylight hours I can run a 300 watt load all day. The display will show the "solar" icon with slightly more watts coming in than going out.
1) Does this mean the load is purely carried by solar?
2) If I hit the inverter with a large load such as a shop vac 1200 - 1500 watts. The inverter "charge" light begins blinking and the fans ramp up. The "solar" will show around 2300 watts with 1200 - 1500 watts going out. Even if the vac is only on a minute or 2 the charging will continue at around 1200 watts for 1/2 hour until it tops up the battery. At that point the "charge" light will stop blinking, and the fans ramp down. Since the solar appears to be pulling in more than enough to power the load, why does the Growatt go into bulk charge? Shouldn't the load have been purely on solar?
3) With no load - after the "charge" light quits blinking the display will still show the solar icon with anywhere from 50 - 100 watts coming in. Is that just to maintain the unit, or is it actually still powering the battery - even though the "charge" light is solid?
4) If the inverter display is showing the "solar" icon with current coming in does that mean that it is indeed using solar, or do I need a computer program to see the details?

If the Growatt's "solar" icon showing connection and current means it is still using solar to power the load, it would appear my unit is not having the problem of cutting off solar after the battery is fully charged. I purchased the unit from Ian in February 2022, so did something change (for the better) recently?

Thank you for your help!

 

[JLBinTN]

Suddenly, for no discernable reason, my Growatt has decided to power loads using solar input even though the battery is full, rather than shutting solar off, running the battery down a few percent, and then cycling back an forth. Anybody else experiencing this?

 

[Sunshine22]

Suddenly, for no discernable reason, my Growatt has decided to power loads using solar input even though the battery is full, rather than shutting solar off, running the battery down a few percent, and then cycling back an forth. Anybody else experiencing this?

I can't say that I've seen it recently, but yes - sporadically. I don't have AC in, so solar is the only source. It still charges up to ~57V and stops charging. It will show the Solar icon even if it is using a bit of battery (less coming in than going out) even during full sun. But, sometimes it will show significantly more solar coming in than going out. I have no idea why this is. I figure it's to condition the batteriy? I don't have BMS or anything, so I doubt it's actually float charging?