Help wanted-Growatt/MPPT users.

[apctjb]

Only way to get it to start charging again, seems to be to turn it off and back on

Cycling on/off does start charging cycle. Having observed mine for going on a year I can say with some confidence that left alone they do resume charging. On some days it seems like they are not harvesting every electron they could, but on the grand scheme of things they charge sufficiently to power the loads and keep the battery charged.

 

[cotrailhead]

I agree. My mppt does not harvest every electron available unless it i shut it down and restart it. Then it will enter a bulk cycle. I was really concerned when I was just watching voltages and didn’t have a shunt. After getting the shunt I realized the high voltage was not necessary for a high state of charge. The mppt seems designed to only occasionally use a high voltage to reach a high state of charge. This can be concerning when there is a storm coming or days of clouds where you know you are entering with less than a full state of charge because the mppt is being lazy with its duty. However, with enough battery capacity you should be able to last a few days until the sun comes back out or worst case you have to rely on your grid or generator. My theory was that it was designed this way to avoid holding lifepo4 at a high state level f charge for prolonged periods. I have phones that when left plugged in for days maintain the battery at 65%. It’s not ideal but it may prolong battery life. Ive seen multiple threads describing this problem in slightly different ways. This may or may not be OP’s case, but I’ve never heard of any solutions other than manually restarting the inverter every day. It’s not a setting solution.

 

[SPockets14]

Cycling on/off does start charging cycle. Having observed mine for going on a year I can say with some confidence that left alone they do resume charging. On some days it seems like they are not harvesting every electron they could, but on the grand scheme of things they charge sufficiently to power the loads and keep the battery charged.

So today, one array carried the load...the other charged 0% for a total of around 600 watts today. That should have been 2kW, with some power going into the battery. Was a bad solar day...but my brother wasn't home so the load wasn't much. The batteries were not full. Stinks to lose that much solar...just seems like something isn't right

 

[derekisastro]

Not sure if what I am adding will help as my issue appears different but I do wonder if they may be some related factor with my issue.

I am running a single unit, Growatt 24V SPF 3000TL LVM, and I am also not running enough panels at the moment that I have the issue of losing solar energy, my issue still relates to the charging of the unit though. My settings are as follows ...

Whenever the unit begins charging with the utility, it never reaches the bulk charge before it stops charging. Charging usually stops at around the 27V mark and I have yet to understand why it does. During the day I get about 1-2kw of solar but my bank is almost 11kw so I do use the utility to charge the remainder of the battery. My current load will use the 11kw in a day or 2.

My experience might be completely unrelated to the topic of this post but I am at a loss to understand how or why the Growatt behaves how it does for my system and my settings.

 

[Zwy]

Not sure if what I am adding will help as my issue appears different but I do wonder if they may be some related factor with my issue.

I am running a single unit, Growatt 24V SPF 3000TL LVM, and I am also not running enough panels at the moment that I have the issue of losing solar energy, my issue still relates to the charging of the unit though. My settings are as follows ...
View attachment 83134
Whenever the unit begins charging with the utility, it never reaches the bulk charge before it stops charging. Charging usually stops at around the 27V mark and I have yet to understand why it does. During the day I get about 1-2kw of solar but my bank is almost 11kw so I do use the utility to charge the remainder of the battery. My current load will use the 11kw in a day or 2.

My experience might be completely unrelated to the topic of this post but I am at a loss to understand how or why the Growatt behaves how it does for my system and my settings.

What are you using for BMS and batteries?

 

[derekisastro]

What are you using for BMS and batteries?

Daly Smart BMS 100amp 24v.

DIY LiFePO4 battery bank, 8s, just under 11kwh.

 

[Zwy]

Look at your settings in the BMS and what each cell reads during charging. You can have one cell that is a runner and hits the high voltage limit set in the BMS. This will stop any charging.

For my truck camper I run a Daly 250A Smart BMS and a Growatt SPF3000TL and it has worked flawlessly. This most likely is a settings problem.

List the settings and cell voltages from the BMS. Was the bank top balanced?

 

[derekisastro]

Look at your settings in the BMS and what each cell reads during charging. You can have one cell that is a runner and hits the high voltage limit set in the BMS. This will stop any charging.

For my truck camper I run a Daly 250A Smart BMS and a Growatt SPF3000TL and it has worked flawlessly. This most likely is a settings problem.

List the settings and cell voltages from the BMS. Was the bank top balanced?

Hi Zwy,

The pack was top-balanced. Unless it is some setting I have not seen, then I don't think it's a settings issue. I am monitoring the high cell voltage and the low cell voltage over time. It does not appear to be a runner cell but I will continue to monitor it. I'll let you know when I get home to check the data.

 

[Bossrox]

Very interesting thought. I had posted previously asking about the issue of having PV negatives tied and all the responses were it would not be an issue. I only have 1 charging relay with my BMS so that poses a new problem with lots of rewiring.

Do you know why having PV negatives common is a problem for Growatt?

I have 2 growatt mppt chargers tied to a common panel ground with no issues however I believe it causes them to take on a master/slave profile I would expect from being comm connected which they aren't. When my load is below what 1 charger can handle, the other goes idle til it's called for. Just kinda odd, I would've expected them both share the load but that's not a big issue.

 

[Bossrox]

I'm trying to get some tech help from signature solar on my growatt mppt chargers. The manual is far from being comprehensive & signature doesn't know enough about them to answer my ?'s nor can I get growatt to reply.
What I can't figure out is there appears to be a voltage input limit depending on the output voltage, 150v for 48v, 100v for 24v & 50v for 12v but the charger says it can do 250v so that doesn't make sense. Then I can't find out if you can can do remote monitoring & settings adjustments in house without connecting to their servers. Then no mention if 2 or more chargers are suppose to be comm connected. If I can ever get that info, I do a youtube for others with the same ?'s

 

[derekisastro]

Look at your settings in the BMS and what each cell reads during charging. You can have one cell that is a runner and hits the high voltage limit set in the BMS. This will stop any charging.

For my truck camper I run a Daly 250A Smart BMS and a Growatt SPF3000TL and it has worked flawlessly. This most likely is a settings problem.

List the settings and cell voltages from the BMS. Was the bank top balanced?

I can confirm that no cell has gone over the BMS set limits, no cell is even getting over 3.45V

On another post on this forum, I found reference to possible issues with 'charge profile' in the "USE" settings on the Growatt inverter such that the inverter stops charging the battery, not at the Bulk setting (28.0V for me) as it should but instead it is stopping AC charging at either the Float setting (27.2V for me) or possibly even the Back to Battery Voltage (26.8V for me).

I will continue to monitor this over a few charge cycles to see if I can see a pattern.

 

[Zwy]

I have my Float set 0.5V below the Bulk charge setting. Yours is 0.8V, I can't see that being the cause. You could set Float 0.1V below Bulk.

Will recently stated he runs LFP to 100% charge anymore due to low C rate charge and discharge with a solar system and calendar aging will kill capacity faster than running full charge/discharge. I agree with that assessment even though I run around 95% for charge. I have one runner in the knee area and as such my settings have that cell run to 3.55V to 3.60V in Bulk.

 

[derekisastro]

I have my Float set 0.5V below the Bulk charge setting. Yours is 0.8V, I can't see that being the cause. You could set Float 0.1V below Bulk.

Will recently stated he runs LFP to 100% charge anymore due to low C rate charge and discharge with a solar system and calendar aging will kill capacity faster than running full charge/discharge. I agree with that assessment even though I run around 95% for charge. I have one runner in the knee area and as such my settings have that cell run to 3.55V to 3.60V in Bulk.

Thanks for your repeated input.

I can say that the last few charges cycles, of AC charging of the battery, have all ended within 0.1 volts of the "Back to Battery Voltage (26.8V for me)". It seems to me to be of too much coincidence to not be a factor, if not the cause of my issues. I don't understand why it's doing it.

It is very possible, I've yet to delve in deep into the data but initial inspection seems to suggest the following, once the battery gets low enough to go to the grid (at 24.4 V) the grid kicks in, to BOTH carry the load and charge the battery, and then when it hits the "Back to Grid" setting for the battery, it also stops charging. I guess on some level it makes sense but I was not aware that this was meant to function this way.

I am going to test by putting the back to grid charge level at a higher, 27.2 or 27.6 V rather than 26.8.

I'll update when I have more data.

 

[derekisastro]

Yep, changed the "Back to battery" setting, and now whenever AC charging kicks in, it goes to the "Back to Battery" setting (currently using 27.6). Again, in hindsight, I guess this kind of makes sense.

 

[coolbz]

What triggers resumption is still a mystery but it appears to be when voltage falls below a certain value which is not directly (perhaps indirectly) user setable.

Thanks for sharing your experience! I have the exact same issue and question with my Growatt 3000 48v ES single inverter recently.

So basically, after the system reach CV, it may stop solar charging into the next day, unless battery voltage drops to some level, which does not appear to be settable anywhere. With CV 55.4, FV 53.5 and my battery sit at 52.5 while not charging under full sun. I am able to trigger solar charge by starting a 1500watt heat gun for a few seconds. From battery BMS, I can tell volt dropped to 51.63 at one point.

 

[coolbz]

Thanks for sharing your experience! I have the exact same issue and question with my Growatt 3000 48v ES single inverter recently.

So basically, after the system reach CV, it may stop solar charging into the next day, unless battery voltage drops to some level, which does not appear to be settable anywhere. With CV 55.4, FV 53.5 and my battery sit at 52.5 while not charging under full sun. I am able to trigger solar charge by starting a 1500watt heat gun for a few seconds. From battery BMS, I can tell volt dropped to 51.63 at one point.

A related question to Growatt and battery charging control. If using a Growatt compatible battery (with BMS communication), is there any additional setting that controls charging more precisely, for example start charging when SOC drop below a value? I don't see that type of setting in Growatt menu. So what's the point of using Growatt compatible battery?

 

[Zwy]

Thanks for sharing your experience! I have the exact same issue and question with my Growatt 3000 48v ES single inverter recently.

So basically, after the system reach CV, it may stop solar charging into the next day, unless battery voltage drops to some level, which does not appear to be settable anywhere. With CV 55.4, FV 53.5 and my battery sit at 52.5 while not charging under full sun. I am able to trigger solar charge by starting a 1500watt heat gun for a few seconds. From battery BMS, I can tell volt dropped to 51.63 at one point.

Your Bulk setting is too low, you should be looking for something in the 3.5V to 3.6V per cell. Set Float 0.5V below that.

Bulk 56V to 57.5V, Float 55.5V to 57V

There are other settings, read the manual 10 times if needed. If you really want answers, list all of your settings in order.

 

[coolbz]

Your Bulk setting is too low, you should be looking for something in the 3.5V to 3.6V per cell. Set Float 0.5V below that.

Bulk 56V to 57.5V, Float 55.5V to 57V

There are other settings, read the manual 10 times if needed. If you really want answers, list all of your settings in order.

I don’t agree my bulk is too low. Someone may need higher setting because there battery internal resistance is higher. But with 55.5v bulk, my battery SOC reach 100% BEFORE the whole battery pack reach 55.5v to stop charge so it already overcharge a little bit by the time it stops at 55.5. And it will over charge too much if I set even higher.

By the way my settings were recommended by Ian at Growatt.

I think the key issue is Growatt does not provide this resume charge setting/condition to end user as original poster reported. Or there is software bug in their firmware.

 

[Zwy]

I don’t agree my bulk is too low. Someone may need higher setting because there battery internal resistance is higher. But with 55.5v bulk, my battery SOC reach 100% BEFORE the whole battery pack reach 55.5v to stop charge so it already overcharge a little bit by the time it stops at 55.5. And it will over charge too much if I set even higher.

Battery chemistry? You didn't state whether it is LFP, LiIon, FLA, etc.

If LFP, 16S configuration, then yes, it's too low.

If your BMS is cutting off charging on LFP at voltages higher than what you posted, then you need a top balance if it is a DIY pack. If it's a LFP manufactured battery, well, you should return it.

By the way my settings were recommended by Ian at Growatt.

That would depend on battery chemistry. Ian should have been able to advise you on your charging problem, that is, if you purchased it from him. If purchased elsewhere, it wasn't worth it and could be the problem.

I think the key issue is Growatt does not provide this resume charge setting/condition to end user as original poster reported. Or there is software bug in their firmware.

No, it's your settings. I have found responding to these threads (which I should quit helping those who don't read and understand the manual) that is always a settings problem.

 

[coolbz]

Battery chemistry? You didn't state whether it is LFP, LiIon, FLA, etc.

If LFP, 16S configuration, then yes, it's too low.

If your BMS is cutting off charging on LFP at voltages higher than what you posted, then you need a top balance if it is a DIY pack. If it's a LFP manufactured battery, well, you should return it.


That would depend on battery chemistry. Ian should have been able to advise you on your charging problem, that is, if you purchased it from him. If purchased elsewhere, it wasn't worth it and could be the problem.


No, it's your settings. I have found responding to these threads (which I should quit helping those who don't read and understand the manual) that is always a settings problem.

It is LFP. As I said, there is no absolute correct voltage like you insisted, because a number of reasons.

A bit of lower bulk voltage should NOT be the reason that it does NOT charge in the next day when battery voltage is below both bulk and float.

The manual clearly doesn't explain every user scenarios.

So the question is (as original poster asked): What parameter controls the starting of solar bulk charge process?

The answer of this question shouldn't be dependent on your battery chemistry, balanced or not, etc. No one so far is able to answer this question.

If you are Growatt employee, I suggest you to check your software source code to find out. Otherwise, you won't know for sure.

It is a software matter (issue).