What Happens When a Growatt SPF 3000TL LVM-ES Hits Low Battery Cutoff?

[maximus57]

My experience with the Growatt SPF 3000TL LVM-ES is that it draws about 40-50 watts from the batteries even when it is in bypass mode. This adds up to about 1kwh a day drain. So what happens when there is lack of solar and the batteries get down to the low voltage cutoff? Does it shut completely down and even disable the bypass? My experience so far is that if the unit is shut off it will not even do the bypass. I can't have my power go out because the stupid inverter drained the batteries so low that it kills the bypass mode.

 

[timselectric]

Set grid charging for 3a. Or the lowest setting. To make up for it.

 

[maximus57]

I am actually working on figuring out grid charge settings for my situation. I just really wondered if that is what I need to do, but your response indicates that I do need to do that. I don't want to give up too much loss for grid charging, but also can't afford to have it go offline.

 

[timselectric]

I am actually working on figuring out grid charge settings for my situation. I just really wondered if that is what I need to do, but your response indicates that I do need to do that. I don't want to give up too much loss for grid charging, but also can't afford to have it go offline.

I'm not 100% sure. But I don't think that unit can operate without the battery.
I would just limit the grid charging to just cover the consumption.
In the beginning, this is what I did. To keep the battery from going too low.
I wanted to keep some reserve , in case the grid went down.

 

[maximus57]

I am working on setting up limited grid charging, but it isn't strait forward as I would like, although I am sure I will get it figured out. It kind of sucks having to do that too. The whole point of going solar is to be able to be less off the grid, but yet there is still this tether.

 

[timselectric]

I am working on setting up limited grid charging, but it isn't strait forward as I would like, although I am sure I will get it figured out. It kind of sucks having to do that too. The whole point of going solar is to be able to be less off the grid, but yet there is still this tether.

I thought that this was going to be while in bypass mode. (Loads being fed by the grid)
Maybe I misunderstood?

 

[maximus57]

Yes, it is while in bypass mode, but as far as I can tell my options are limited. I am trying to figure out the cryptic way to set up timed utility charging. From what I can tell I can set it as low as a 2 hour charge at 10 amps (which is about what is needed to cover the daily draw without any sun). I would set this for late night to get the lower rate. It looks like there is a way to set it to only charge off grid if solar isn't available, but that would put the charge into the higher utility electricity rate time.

 

[timselectric]

When I was doing it. I just set it to charge at like 3a from the grid.
I didn't set any TOU stuff. I was already powering everything from the grid. So another 150w didn't matter to me.

 

[maximus57]

You must not have the inverter that I do. My minimum is 10 amps, and I have 3 inverters synced together so I end up with 30 amps. I am still trying to confirm the time setting, I was hoping for a minimum of 1 hour, but I think it might be 2 hours minimum. The only good thing is that 2 hours at 30 amps is about the kWh the inverters will draw in a day will no solar.

Also, when I say bypass mode, I mean it went into bypass mode because the battery voltage went below the threshold. My system is set to run on battery when there has been enough solar. The idea is to use as much solar as possible and as little grid as possible. Having to charge the batteries from the grid to keep from losing power was not part of the plan, but I guess I will have to deal with it. It will just be a bit of a loss in efficiency.

 

[timselectric]

It might be easier to just raise the setting for switching to bypass mode.
Enough to cover it.

 

[maximus57]

The highest I can go is 51.2v. Under ideal conditions that leaves about 2 days with very little solar (very overcast). Some of my setting option limitations suck, but that is what I get for going cheap Chinese.

I did just get a crazy idea thinking of your 3 amp charge. If I could get a 3 amp charger, I could run that off an outlet full time. When running off battery it would be a small loss from charging itself. But when on bypass it would be charging from the grid. Hmmm... wheels turning, have to think more about that and price a 3 amp charger. Could possibly run it through a battery monitor/cutoff to only charge if voltage was below a certain set point. More work and more up front money, but something to think about.

 

[timselectric]

I did just get a crazy idea thinking of your 3 amp charge. If I could get a 3 amp charger, I could run that off an outlet full time. When running off battery it would be a small loss from charging itself. But when on bypass it would be charging from the grid. Hmmm... wheels turning, have to think more about that and price a 3 amp charger. Could possibly run it through a battery monitor/cutoff to only charge if voltage was below a certain set point. More work and more up front money, but something to think about.

I like it.

 

[maximus57]

So I have an update on this. I have not yet implemented my crazy idea of using a small charger, and I am glad. I have my utility charge set to 0001, which charges from 12am-2am. However, in my observation I found that if it is still running on battery during that time it does not charge from utility! That is perfect! That is not documented anywhere, but my observations are conclusive.