Hybrid Inverter Output Priority

[JWLV]

I just watched Will's video about the Growatt inverter: No Battery Solar Power System: Growatt SPF 3000TL LVM-ES

So I started to read up on this particular inverter. It's a hybrid inverter, which includes a MPPT charge controller and inverter with three output modes.

I have a question about the output modes in one specific scenario.

The Growatt has 3 output modes.

• Utility first: Utility power your load as first priority, battery power and solar on when Utility not available.
• Solar first: Solar energy power your load, battery energy active when solar power doesn't work.
• SBU priority: Solar power first, then battery power, then Utility.

My hypothetical scenario:
Let's say my solar panels are providing a total of 500 watts at 150VDC and the Growatt is set to SBU Priority (3rd mode). It's a bright sunny day and the panels are producing exactly 500 watts. Let's also assume that my battery is completely drained and the Growatt just started the process of charging it from the panels. If I connect a load that's 750 watts, it's obvious that the solar panels can't provide all that power on its own (it'll be short by at least 250 watts). Since the battery will not be able to provide any power, the output mode will switch to utility.

My question is, will the Growatt cut off the solar panels completely from the output and draw the entire 750 watts from the utility or will it draw as much as it can (up to 500 watts) from the solar panels and the rest from utility?

I've also looked at several other similar hybrid inverters that have 3 output modes. Prices range from $400 to $900. A couple of them even look identical to the Growatt, just with a different name on the front.

 

[mrzed001]

Hi !
Please do not call them hybrid inverters. They are NOT.
They are Off-grid (with grid support) inverters.
A hybrid inverter can function as Grid-tie and produce power to utility. An off-grid inverter can not.

As for your question:
There are 3 different scenarios depending on the inverter's type:

1. Separated: can only give power from Utility, or Solar (+Battery)
2. Inner limiter: can combine Utility and Solar (+Battery) power like 3kW from solar and the rest 1kW from utility (like a grid-tie work into the output line)
3. Double conversion: Utility power is converter to DC. Combines Utility and Solar (+Battery) power like 3kW from solar and the rest 1kW from utility (own noise free sine wave).
   

Off-grid inverters most used are MPP Solar, EASun, Growatt. Not sure but maybe MPP is the original. Also I think they are all made by Voltronic.

 

[Cidpineda]

I just watched Will's video about the Growatt inverter: No Battery Solar Power System: Growatt SPF 3000TL LVM-ES

So I started to read up on this particular inverter. It's a hybrid inverter, which includes a MPPT charge controller and inverter with three output modes.

I have a question about the output modes in one specific scenario.

The Growatt has 3 output modes.

• Utility first: Utility power your load as first priority, battery power and solar on when Utility not available.
• Solar first: Solar energy power your load, battery energy active when solar power doesn't work.
• SBU priority: Solar power first, then battery power, then Utility.

My hypothetical scenario:
Let's say my solar panels are providing a total of 500 watts at 150VDC and the Growatt is set to SBU Priority (3rd mode). It's a bright sunny day and the panels are producing exactly 500 watts. Let's also assume that my battery is completely drained and the Growatt just started the process of charging it from the panels. If I connect a load that's 750 watts, it's obvious that the solar panels can't provide all that power on its own (it'll be short by at least 250 watts). Since the battery will not be able to provide any power, the output mode will switch to utility.

My question is, will the Growatt cut off the solar panels completely from the output and draw the entire 750 watts from the utility or will it draw as much as it can (up to 500 watts) from the solar panels and the rest from utility?

I've also looked at several other similar hybrid inverters that have 3 output modes. Prices range from $400 to $900. A couple of them even look identical to the Growatt, just with a different name on the front.

yes it will pull on solar first all 500 watt

 

[rsi77]

I had the exact same question. Thanks for beating me to it, and thanks for the answer.
I just purchased the unit. This will be my first solar system. I have yet to buy the panels. I will be posting some questions about the minimum voltage required from the panels.

 

[Cidpineda]

3kw of panels is sufficient for a 300AH 48volt battery for me but in the back i have another 2kw panel powered by MAKESKYBLUE V119 60AH facing the sunset window AC starts at 10AM to 2PM then 2 kids playing PC till midnight then morning i still have 49volts in my battery to cut of at 48.6

I had the exact same question. Thanks for beating me to it, and thanks for the answer.
I just purchased the unit. This will be my first solar system. I have yet to buy the panels. I will be posting some questions about the minimum voltage required from the panels.

 

[rsi77]

I currently have only 100 Ah of 48V battery power (2x24V 100Ah in series). As I understand it I can Max out my panels per the rating of the Growatt and the only downside to not adding batteries will be that I will run out of power relatively quickly at night, or when solar input is decreased.
So in theory if I want to use 340W panels with Voc = 40.66, I could connect an array of 6s2P which would give me an array voltage of 244, with an array power of 4.1kW. Is my math good?
Thanks,
Ron

 

[Cidpineda]

I currently have only 100 Ah of 48V battery power (2x24V 100Ah in series). As I understand it I can Max out my panels per the rating of the Growatt and the only downside to not adding batteries will be that I will run out of power relatively quickly at night, or when solar input is decreased.
So in theory if I want to use 340W panels with Voc = 40.66, I could connect an array of 6s2P which would give me an array voltage of 244, with an array power of 4.1kW. Is my math good?
Thanks,
Ron

244? max is 250 i would not do that if its me...and 12pcs of 340 watt is 4080 so yea 4.1 but max is 4000watt so nonononono 3S3P? anyways you have alot of panels so 1 hour your bat will be full. or just use 5s1p for now

 

[rsi77]

Well I didn't get the panels yet, I'm just trying to best understand my options. I hadn't realized that we wanted to always stay away from the max voltage--I thought there was some "wiggle room" to go a little above, and that this would help overall performance by giving more push so the current can get through even during times of lower solar input. But 5s1p for now sounds like a good idea, and will be cheaper. It will give me a chance to see how the whole thing works. I can try to "max it out" later, when I better understand how things work.

 

[wattmatters]

I hadn't realized that we wanted to always stay away from the max voltage--I thought there was some "wiggle room" to go a little above, and that this would help overall performance by giving more push so the current can get through even during times of lower solar input.

It's very important not to exceed the Voc limit of your solar controller. It should be a decent amount higher than the preferred operating voltage range of the MPPT in any case.

It's also important to know that the Voc rating of your panels is when they are at standard temperature and conditions (STC) while the actual open circuit voltage is temperature dependent.

Voc goes up as temperature falls, so if your panels are likely to experience cold temperatures then the Voc will be quite a bit higher. At freezing it might be nearly ~10% higher, and if your area gets well below freezing then you may want to allow for the chance of 20% higher than the rated Voc. Panels will typically state what their Voc temperature coefficient is and list it as voltage per degree Kelvin (or Celcius).

This is why when designing arrays you need to allow some Voc headroom.

 

[sege]

With SBD priority set can you configure how much battery to use or will it drain it before using utility? How do you configure it? Voltage?

 

[wattmatters]

With SBD priority set can you configure how much battery to use or will it drain it before using utility? How do you configure it? Voltage?

The battery voltage for cut over to utility is user definable. You can also set the voltage when it cuts back to the battery.

 

[rhinehart22]

I am looking at building a similar system: grid tie with battery backup or off grid with grid support, not sure which yet. One thing I haven't been able to find an answer on is what happens if your load exceeds the maximum output of 3kW for this inverter for example? Are you completely limited by the inverter, does it which all to grid, does the inverter provide the max of 3kW and the grid makes up the rest and bypasses the inverter?

 

[wattmatters]

One thing I haven't been able to find an answer on is what happens if your load exceeds the maximum output of 3kW for this inverter for example?

Which inverter?

A grid tied inverter operates in parallel with the grid supply and both can provide power to the home if required. The power limit then is the inverter's output capacity + the grid supply capacity.

An off grid inverter with an AC input from the grid puts the inverter in series between the grid supply and your (off-grid) household loads. IOW the inverter now sets the upper limit of supply. The grid pass through power limit may be higher than what the inverter can produce from its solar/battery sources but that's something you'd have to check from the inverter's specifications.

 

[400bird]

Hi !
Please do not call them hybrid inverters. They are NOT.
They are Off-grid (with grid support) inverters.
A hybrid inverter can function as Grid-tie and produce power to utility. An off-grid inverter can not.

I just want to say for everyone that the definition of a hybrid inverter isn't set in stone.

Hybrid implies the combination of two things.

In this case, I would say, and so do others, that a hybrid inverter is a charger controller plus battery inverter in one unit.

Could be grid tied or not.