Current charging and discharging amp value setting

[max99]

I have Solis 3kW inverter with
Battery Phylontech 4.8kWh
Phylon US5000
4.8kWh Li-ion solar battery 48v
With I think 100A discharge capability.

The current charge and discharge current setting for both are 80A.

Charge SOC 20%
Force discharge 15%
What is ideal charge/discharge current setting?

As this has impact on battery longevity.

Also, as I only have one battery would 2 be better for running the house mainly from battery?

Any thoughts, as I am a rookie!

 

[MisterSandals]

You need to base these decisions on what YOUR loads are.
What loads will be "running the house"?

 

[max99]

You need to base these decisions on what YOUR loads are.
What loads will be "running the house"?

Thanks MisterSandals for your quick response.
OK, so I need to work out how much kw usage I use over a week or more to come up with an average.
Is this right? I'm a total rookie.

 

[MisterSandals]

OK, so I need to work out how much kw usage I use over a week

Determine kWh (kilowatt hours) on a daily basis is most important for sizing arrays and battery banks. The max load is important to your questions in your OP.

 

[BryceFreeman]

Hi, the best way to keep a Li-ion battery healthy is charging and discharging at 0.1C, which means the current should be 0.1*100AH=10A. How many batteries are needed bases on how many power you will need.

 

[max99]

Hi, the best way to keep a Li-ion battery healthy is charging and discharging at 0.1C, which means the current should be 0.1*100AH=10A. How many batteries are needed bases on how many power you will need.

Interesting, BryceFreeman, the charging/discharging current is set to 80A. So, this would seem quite high.
I understand charge SOC and force charge percentages and what they are for but really don't get this charge/discharge Amp thing.
Should I change the 80A to 10A and see what happens?
Don't want to damage battery.
Being a rookie to all this.

 

[max99]

Determine kWh (kilowatt hours) on a daily basis is most important for sizing arrays and battery banks. The max load is important to your questions in your OP.

Right, I will monitor daily usage over a period of weeks and then that will give me an idea of the peak usages.
I should ensure the battery capacity is big enough to cater for the majority of the high peaks.
At the moment, I notice that the 4.8kWh battery does export to the grid which can mean the battery is fully charged. My aim is to keep more of the PV power in the battery such that it covers the night time hours.

 

[MisterSandals]

Right, I will monitor daily usage over a period of weeks and then that will give me an idea of the peak usages.

When you gather a day or 2 of daily data we can probably get started and adjust if necessary as more data comes in.

Should I change the 80A to 10A and see what happens?

What does YOUR battery maker recommend? That should be your starting point for making this decision.

Battery Phylontech 4.8kWh
Phylon US5000

Are you sure this isn't Pylon Technologies?

US5000-Pylon Technologies Co., Ltd.

en.pylontech.com.cn

 

[MisterSandals]

 

[max99]

Yes, this is the battery from Phylontech and battery is US5000.

So, setup from BMS is
At 23:28 on 13th Nov 2023

Hoping this setup is correct!

 

[MisterSandals]

So, setup from BMS is

Hoping this setup is correct!

The BMS is to protect the battery so the settings are to keep the voltage within safe range and current within safe range.

By setting the charge current limit at the recommended charging amps, it looks like you are trying to use the BMS to control charging. The charge controller (Solis 3kW inverter) settings should control the charging.

 

[max99]

The above was showing the BMS set up.
I have inserted the Inverter tab below:


The amps etc were set via the Solis menus.
The inverter and BMS tabs are from the app.

Do I need admin access to the inverter to change inverter settings from the Soliscloud site?

 

[SeaGal]

I have Solis 3kW inverter with
Battery Phylontech 4.8kWh
Phylon US5000
4.8kWh Li-ion solar battery 48v
With I think 100A discharge capability.

The current charge and discharge current setting for both are 80A.

Charge SOC 20%
Force discharge 15%
What is ideal charge/discharge current setting?

As this has impact on battery longevity.

Also, as I only have one battery would 2 be better for running the house mainly from battery?

Any thoughts, as I am a rookie!

I'll try and give my 2p, having a Solis, but with DIY battery. As @MisterSandals noted, it should be Pylontech, not Phylon...

According to the spec sheet I saw, the US5000 battery has a recommended max discharge of 50A (*). That equates to 0.5C discharge rate, which is a perfectly safe rate for LiFePO4 cells to discharge at. That battery has a 'peak' = temporary rating of 100A, which you noted, however the Solis will only support 62.5A discharge rate as well as a max of 3000W at 55V. In practice, with the lower voltage of the Pylontech batteries (being 15 cell, rather than 16 cell architecture) you will probably only get a maximum draw from battery alone of around 2700 - 2800W from the Solis, which will be around 55A, irrespective of the number of batteries you deploy.

So personally, I would set the max charge and discharge rate to 50A.

(*) this is different to the value of 80 in the screen shot above, but as they don't know their A's from their Ah's I'd take that with a pinch of salt.

Talking of pinches of salt... regarding this comment...

Hi, the best way to keep a Li-ion battery healthy is charging and discharging at 0.1C, which means the current should be 0.1*100AH=10A.

this suggestion is not helpful or practical at all. Sure, a BMW or VW may be kept more healthy if you never drive it more at 10mph, but you can safely drive it at 50mph without undue wear and tear.

Do I need admin access to the inverter to change inverter settings from the Soliscloud site?

I don't use the SolisCloud, but you can access advanced settings via the inverter's front screen using passcode 0 0 1 0.

HTH.

 

[max99]

I'll try and give my 2p, having a Solis, but with DIY battery. As @MisterSandals noted, it should be Pylontech, not Phylon...

According to the spec sheet I saw, the US5000 battery has a recommended max discharge of 50A (*). That equates to 0.5C discharge rate, which is a perfectly safe rate for LiFePO4 cells to discharge at. That battery has a 'peak' = temporary rating of 100A, which you noted, however the Solis will only support 62.5A discharge rate as well as a max of 3000W at 55V. In practice, with the lower voltage of the Pylontech batteries (being 15 cell, rather than 16 cell architecture) you will probably only get a maximum draw from battery alone of around 2700 - 2800W from the Solis, which will be around 55A, irrespective of the number of batteries you deploy.

So personally, I would set the max charge and discharge rate to 50A.

(*) this is different to the value of 80 in the screen shot above, but as they don't know their A's from their Ah's I'd take that with a pinch of salt.

Talking of pinches of salt... regarding this comment...

this suggestion is not helpful or practical at all. Sure, a BMW or VW may be kept more healthy if you never drive it more at 10mph, but you can safely drive it at 50mph without undue wear and tear.


I don't use the SolisCloud, but you can access advanced settings via the inverter's front screen using passcode 0 0 1 0.

HTH.

Thx SeaGal for your comments. I will try 50A rather than 80A and see if that makes any difference.

I have one more question related to what you wrote:
"will probably only get a maximum draw from battery alone of around 2700 - 2800W from the Solis, which will be around 55A, irrespective of the number of batteries you deploy"

I have one Pylontech 4.8KWh battery does that mean it can store upto 4800w. So, if I had 2 batteries then it would store upto 9600w or does the inverter restrict the storage capacity anyway?

In other words adding another battery will not make me self sufficient with respect to drawing power from the grid?

 

[SeaGal]

I have one Pylontech 4.8KWh battery does that mean it can store upto 4800w. So, if I had 2 batteries then it would store upto 9600w or does the inverter restrict the storage capacity anyway?

In other words adding another battery will not make me self sufficient with respect to drawing power from the grid?

You are confusing power, measured in watts (symbol = capital W) with energy (or capacity) of your battery which is measure in kWh (that's a small k there; FYI capital K is Kelvin, a measure of temperature)).

A 4.8kWh battery will hold a maximum 4.8kWh of energy. That is 4800Wh which could be used by drawing a power of (say) 2400W over a 2 hour period. If you were to double your battery capacity to 9600Wh you could then draw power of 2400W over 4 hours. (for simplicity I am ignoring 'usable capacity' which will typically be 90% of your battery's headline figure).

But with your 4800Wh battery capacity you cannot draw 4800W for 1 hour, due the the power limit of your Solis.

With regard to being self-sufficient from the grid, that is another whole level of complexity - you will need to calculate your solar production, maximum power draw, daily energy usage and how many cloudy/rainy days you need to get through.

 

[max99]

You are confusing power, measured in watts (symbol = capital W) with energy (or capacity) of your battery which is measure in kWh (that's a small k there; FYI capital K is Kelvin, a measure of temperature)).

A 4.8kWh battery will hold a maximum 4.8kWh of energy. That is 4800Wh which could be used by drawing a power of (say) 2400W over a 2 hour period. If you were to double your battery capacity to 9600Wh you could then draw power of 2400W over 4 hours. (for simplicity I am ignoring 'usable capacity' which will typically be 90% of your battery's headline figure).

But with your 4800Wh battery capacity you cannot draw 4800W for 1 hour, due the the power limit of your Solis.

With regard to being self-sufficient from the grid, that is another whole level of complexity - you will need to calculate your solar production, maximum power draw, daily energy usage and how many cloudy/rainy days you need to get through.

Thanks for your comments. I don't really understand everything so please bear with me!
I have noticed that when battery gets charged 100% it starts exporting to grid. Is it supposed to do this?
Shouldn't it leave the battery charged up and from PV go to home and grid. Not sure why it discharges from battery.

 

[SeaGal]

Thanks for your comments. I don't really understand everything so please bear with me!
I have noticed that when battery gets charged 100% it starts exporting to grid. Is it supposed to do this?
Shouldn't it leave the battery charged up and from PV go to home and grid. Not sure why it discharges from battery.

Aaaghhh.. too many pronouns for me to understand... can you write that again replacing the "it"s with the corresponding nouns... thanks! ?‍?

 

[max99]

When the battery is charged 100% then the surplus energy is used by the house and also exported to the grid
Then there are occasions when the battery is being discharged and is exported to the grid. This occurs even though no discharge time window has been set.
Why does the battery discharge and export to the grid even when the battery is not 100% charged?

 

[SeaGal]

When the battery is charged 100% then the surplus energy is used by the house and also exported to the grid

That is normal, expected behaviour. All surplus energy (i.e. that is not consumed by house load) will be exported unless you had explicitly configured export power limitation (which would not normally be done with your configuration).

Then there are occasions when the battery is being discharged and is exported to the grid. This occurs even though no discharge time window has been set.
Why does the battery discharge and export to the grid even when the battery is not 100% charged?

That sounds as something is incorrectly configured. Check both that the Solis self-mode has been selected, double check that there are no discharge time periods set and check that the CT clamp is around the incoming live meter tail and is the correct orientation.

Assuming there are no discharge time periods set, then the only time that your system should export to grid is if:-
solar generation > (house load + battery charge rate)

If the battery is discharging it is because house load > solar generation, but in no situation should battery discharge to grid (*)

(*) Correction... in no situation should the battery discharge any significant amount to the grid. There may be tiny amounts due to inaccuracy of measuring import and export amounts. Also a few seconds of discharge to grid will happen when a load is switched off - i.e. it takes a few seconds for the inverter to adjust to the new house load.

 

[max99]

That is normal, expected behaviour. All surplus energy (i.e. that is not consumed by house load) will be exported unless you had explicitly configured export power limitation (which would not normally be done with your configuration).


That sounds as something is incorrectly configured. Check both that the Solis self-mode has been selected, double check that there are no discharge time periods set and check that the CT clamp is around the incoming live meter tail and is the correct orientation.

Assuming there are no discharge time periods set, then the only time that your system should export to grid is if:-
solar generation > (house load + battery charge rate)

If the battery is discharging it is because house load > solar generation, but in no situation should battery discharge to grid (*)

(*) Correction... in no situation should the battery discharge any significant amount to the grid. There may be tiny amounts due to inaccuracy of measuring import and export amounts. Also a few seconds of discharge to grid will happen when a load is switched off - i.e. it takes a few seconds for the inverter to adjust to the new house load.

Thank you both. It's all new so reassuring comments help. I will raise a Solis support ticket to see what they say.
I'll do that before I change the AMPs from 80 to 50 and see what happens.
Thanks again