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Deye 8kW Hybrid Inverters Charge/Discharge Configurations?


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Posted (edited)

I hope someone can explain to me the principles of Charging/Discharging on the Battery Setup Pages for the Deye 8kW Hybrid Inverters, as it seems they are not "strictly" following the BMS Configurations when "Lithium Mode" is selected.

Note: I have the following configuration:

  • 2 x Deye 8kW Hybrid Inverters running in parallel mode (both are upgraded with the latest Firmware and Software)
  • Both Inverters are connected to a common DC+ and DC- busbar which in turn runs through a 160A DC Fuse which in turn is connected to the Battery Bank
  • 6 x Lithium @ 5.1kW, 48V - 100ah Battery Bank

image.png.aac35cfca5bcffbc2f4befe77f1c503e.png

 

When you configure the Max A Charge and the Max A Discharge, then these seems to be ignore or utilized (I can't find a definite answer with many hours of Googling, or even in the manuals itself - I even looked at the SunSynk manuals), let me explain:

Scenario A:

When there is plenty of Solar then the above Max A Charge limit is easily exceeded and seems to follow the BMS Charge limits ~ this is what is logically expected [my assumption is that DC is bypassed and directly pushed towards charging the batteries following the BMS Charge limits)

Scenario B:

When there is not enough Solar and you have configured the settings to charge from Grid (ie. cloudy days), then the above Max A Charge is strictly enforced ~ this does not make sense, because "Peak Shaving" is not configured, and the Max AC Input for the Grid far exceeds these configured limits.

 

Note: In both Scenario A and Scenario B the Max A Discharge seems to be ignored in Lithium mode resulting in following the BMS Discharge limits ~ this is what is logically expected

 

Questions:

  1. Why is the charging limits taken into account enforcing this configuration and not following the BMS charging limits in Scenario B, but ignoring such in Scenario A?
  2. With regards to the "A" configurations, the Charging / Discharging limits are configured based on the "Voltage" configurations for the Lithium Batteries, if you have 24V connected they will run on 24V, if you have 48V connected they will run on 48V ~ what is the impact and/or reference towards the "A" being used in these screens?

The reason for question 2 is because when you charge from Solar (PV) it runs on X volts and are internally by the Inverters converted to 48V (charging and discharging), but when 220V (AC) from the grid is being used for charging this is stepped-down to 48V and converted to DC, resulting X amps?

 

I don't quite make out of the calculations of the amperage configurations in these sections, because 48V DC @ 40A is vastly different than 220V AC @ 40A ... and I would like to understand which is applied and taken into account? Heck even 48V DC @ 40A is not the same as 48V AC @ 40A.

image.thumb.png.d39299432444b3ae4a169d54339797a9.png

Therefor if the limit configurations on this page is applied, I would like to try and workout based on my setup what would be the best configurable values on these pages, including understanding whether the amperage being referring to on these pages should be calculated as DC @ 48V (due to my Batteries being 48V), and since both Inverters run in parallel mode connected to a common DC+ and DC- busbar, should these values be divided by 2 to compensate for such, etc.?

 

Thanks!

 

 

Edited by RabidBunny
  • 11 months later...
Posted

Hello, 

I have the following setup: 

Three PV strings of 7000 Wp each connected to three Deye Hybrid 8000 W that are set in parallel. I have a battery bank of 5 batteries of 200 AH each. Each battery has a charge / discharge limit of 100 amps. Each battery is individually connected to a combiner box. The three deye inverters are connected to the same combiner box as well. 

I would like to limit the total charge / discharge of the batteries to a total 210 amps. What should the batteries setup in the inverters? Max charge and discharge of 70 amps each or should i set it to 210 amps since they are connect in parallel?

 

can someone help me out? 

Posted (edited)
1 hour ago, Frankista said:

I would like to limit the total charge / discharge of the batteries to a total 210 amps. What should the batteries setup in the inverters? Max charge and discharge of 70 amps each or should i set it to 210 amps since they are connect in parallel?

Set your Charge on each inverter to 70A, for a total of 210A provided together by all three inverters to the common DC battery bus.

If you do the same on the Discharge setting you will limit the combined output of your inverters to +- 10500W, and possibly cause them to trip off.

On the 8.8 kW inverter the MAX you can set on the Discharge is 185A per inverter, but with your battery limit of 500A, I'd suggest setting each inverter Discharge to 166A.

I don't have a Deye inverter or parallel setup on my SunSynk, but a friend with parallel 5K Deye's sets his Charge like this.

Edited by TimCam
Posted

@TimCam thanks a lot for your prompt reply. Since the max discharge for the batteries is at 230 amps (limited by circuit breaker). How would you suggest that I limit the discharge to avoid tripping the circuit breaker? 

What do you suggest to set the discharge value to? 

Posted
3 minutes ago, Frankista said:

@TimCam thanks a lot for your prompt reply. Since the max discharge for the batteries is at 230 amps (limited by circuit breaker). How would you suggest that I limit the discharge to avoid tripping the circuit breaker? 

What do you suggest to set the discharge value to? 

Unfortunately that is a huge limitation, especially for 3x 8.8 kW machines. Is this a new install or an expansion?

If a new install, call the installer and have him upgrade the Battery DC installation.

If an expansion, the same problem, as the Battery side needs upgrading.

Currently your inverters can supply 26.4 kW of power, when powered from batteries only.

Your batteries can supply 25 kW which is fine.

The problem is your DC battery wiring and fuses limit you to 11.5 kW.

 

With the current setup you will have to set each inverters Discharge to 76A for a combined current from the batteries of 228A.

This will power a load of about 11.4 kW from the batteries.

Posted

Ah OK, wasn't aware of the DC limitations on the CB. 

Interesting as on my 5kw parallel setup I only set the limit on the master and that limit (115a in my case) is propagated to the secondary inverter. I'm not hitting any DC limits yet though (125a)

Posted
3 minutes ago, mzezman said:

Ah OK, wasn't aware of the DC limitations on the CB. 

Interesting as on my 5kw parallel setup I only set the limit on the master and that limit (115a in my case) is propagated to the secondary inverter. I'm not hitting any DC limits yet though (125a)

I'll have to ask my Deye friend if his master propagates setting to the slave?  The way he explained it, sounded like he has to set up the slave separately. 🤔

Posted
1 minute ago, TimCam said:

I'll have to ask my Deye friend if his master propagates setting to the slave?  The way he explained it, sounded like he has to set up the slave separately. 🤔

All good, they might have programmed it differently between Deye and Sunsynk. We live and we learn

Posted
32 minutes ago, TimCam said:

Unfortunately that is a huge limitation, especially for 3x 8.8 kW machines. Is this a new install or an expansion?

If a new install, call the installer and have him upgrade the Battery DC installation.

If an expansion, the same problem, as the Battery side needs upgrading.

Currently your inverters can supply 26.4 kW of power, when powered from batteries only.

Your batteries can supply 25 kW which is fine.

The problem is your DC battery wiring and fuses limit you to 11.5 kW.

 

With the current setup you will have to set each inverters Discharge to 76A for a combined current from the batteries of 228A.

This will power a load of about 11.4 kW from the batteries.

This is a new install. I did not turn it on yet… when you are talking about upgrading the battery DC installation, are you talking about the CB of 230 amps between the batteries and the inverters or is there anything else i need to enhance? 

Note that in my current setup the inverters are connected each to a MCCB of 160 amps each that connect to the combiner box that contains the 230 amps circuit breaker… That combiner box containing the fuse and the circuit breaker. See the photo for illustration. There is no installer. I am doing all of this by mhyself. image.thumb.jpeg.e98becb41309ce96996d283f0ae48c00.jpeg

Posted
29 minutes ago, TimCam said:

I'll have to ask my Deye friend if his master propagates setting to the slave?  The way he explained it, sounded like he has to set up the slave separately. 🤔

By the way, when i change the settings on the master, it does propagate on the slaves in a matter of seconds… I am using DEYE and not Sunsynk. 

Posted
53 minutes ago, Frankista said:

This is a new install. I did not turn it on yet… when you are talking about upgrading the battery DC installation, are you talking about the CB of 230 amps between the batteries and the inverters or is there anything else i need to enhance? 

Note that in my current setup the inverters are connected each to a MCCB of 160 amps each that connect to the combiner box that contains the 230 amps circuit breaker… That combiner box containing the fuse and the circuit breaker. See the photo for illustration. There is no installer. I am doing all of this by mhyself. image.thumb.jpeg.e98becb41309ce96996d283f0ae48c00.jpeg

A bit of DIY is OK, but you are installing electrical kit that needs a Certificate Of Compliance.

Looking at the picture, the bus bars look under spec to carry 500A, and wires look thin too.

I would get heavier bus bars, and use 35mm2 cable from the individual batteries to the bus bars.

Each battery fused through a 125A fuse to the bus bars. (Note all battery cables of the same length)

From the bus bars to each inverter use 50mm2 cable through a 230A fuse or CB.

 

If you are in JHB area a good idea would be to contact @Leshen or @Steve87.

 

 

Posted
7 hours ago, TimCam said:

A bit of DIY is OK, but you are installing electrical kit that needs a Certificate Of Compliance.

Looking at the picture, the bus bars look under spec to carry 500A, and wires look thin too.

I would get heavier bus bars, and use 35mm2 cable from the individual batteries to the bus bars.

Each battery fused through a 125A fuse to the bus bars. (Note all battery cables of the same length)

From the bus bars to each inverter use 50mm2 cable through a 230A fuse or CB.

 

If you are in JHB area a good idea would be to contact @Leshen or @Steve87.

 

 

You are right. I’m in the process of changing the cables. The installer did not do it right. 
 

My main question remains: do you recommend that I upgrade the MCB in the combiner box? 

Posted (edited)

The box to the right is labelled battery output... It should be called "fire starter". Your wires are too small and will heat up and melt long before the circuit breaker trips. I am a DIYer myself so I am not discouraging you, but your install will burn down

Fuses are sized to your wires and has nothing to do with the load connected, the fuse/breaker should disconnect before the wire heats up and melts that is the only function. 

Please look at the table to understand what wires you need. 

image.png.8fb59f84dc07ad60e4b8610354ef0ca5.png

 

Get yourself a "Inge: DC 3P Battery Disconnect Box 160A 48VDC (Use NH0 DC Blade Fuse Link) (IngeDNH7-160/30)" with 160A Fuses between each battery and the battery common busbar. Search for some images on the forum, there are some beautiful busbars that the DIYers made

Use 50mm wires. Fuse both positive and negative

 

I am not going to link to any websites selling an example product as my posts were deleted in the past

 

I assume you have installed 3x 8KW to run them in 3-phase mode. Are you running 3 phase pumps?

Edited by iiznh
Posted
9 hours ago, iiznh said:

The box to the right is labelled battery output... It should be called "fire starter". Your wires are too small and will heat up and melt long before the circuit breaker trips. I am a DIYer myself so I am not discouraging you, but your install will burn down

Fuses are sized to your wires and has nothing to do with the load connected, the fuse/breaker should disconnect before the wire heats up and melts that is the only function. 

Please look at the table to understand what wires you need. 

image.png.8fb59f84dc07ad60e4b8610354ef0ca5.png

 

Get yourself a "Inge: DC 3P Battery Disconnect Box 160A 48VDC (Use NH0 DC Blade Fuse Link) (IngeDNH7-160/30)" with 160A Fuses between each battery and the battery common busbar. Search for some images on the forum, there are some beautiful busbars that the DIYers made

Use 50mm wires. Fuse both positive and negative

 

I am not going to link to any websites selling an example product as my posts were deleted in the past

 

I assume you have installed 3x 8KW to run them in 3-phase mode. Are you running 3 phase pumps?

image.thumb.png.37b051e454884f38ec14bc1fbff265ec.png

Posted
1 minute ago, Frankista said:

Would the above setup work?

With the correct sized wires any system could work. As long as the batteries carry equal load and their wires have similar internal resistance.

What is the intended application for this system? 

Are you planning on drawing continuous high power? Will there be large spikes as pumps start up?

If this is a home then it might be total overkill. It depends on how you plan to use the power

 

 

 

 

Posted

 

1 minute ago, iiznh said:

With the correct sized wires any system could work. As long as the batteries carry equal load and their wires have similar internal resistance.

What is the intended application for this system? 

Are you planning on drawing continuous high power? Will there be large spikes as pumps start up?

If this is a home then it might be total overkill. It depends on how you plan to use the power

 

 

 

 

This is for a very large home with over 40 kWh / day of consumption. The whole setup will remain in single phase. The draw of power is not continuous. You have a large consumption at night and when the electric cars are charging. The max current on the load is physically limited to 50 amps (intentionally).

As you have suggested we will change the cables and will put them as such:

- between inverter and MCCB 50 mm2 (we have three 160 amps MCCB seen on the photo above)

- Between  MCCB and bus bars, cables to 50 mm2. 

- will add 5 fuses (or DC Circuit breakers) each connecting the batteries. Will use 25 mm2 cables to connect the CB / fuse to the batteries. 

Question: would you recommend, for point 3 fuses or DC CB?

Posted
3 hours ago, Frankista said:

image.thumb.png.37b051e454884f38ec14bc1fbff265ec.png

 

Fuses are preferred. On the diagram above, between the batteries and bus bars, replace the "MCB DC100A" with 125A fuses, and use 35mm2 cabling.

Throw out the 210A MCB in the combiner box, and wire directly from the bus bars through 50mm2 cabling and 200A to 230A fuses to each inverter individually.

*Note* Each 8.8 kW inverter can draw up to 185A from the batteries, so 160A fuses or CB is under spec'ed.

 

Fuses or CB's are not there to disconnect the inverter from batteries when the batteries are providing the load, but only as a last form of protection.

To disconnect the batteries for "maintenance, etc" the batteries must not be under load, and be switched off at the battery first, then fuses or CB can be disconnected.

 

Posted
2 hours ago, Frankista said:

This is for a very large home with over 40 kWh / day of consumption.

40kWh....is not a lot of power

 

2 hours ago, Frankista said:

You have a large consumption at night and when the electric cars are charging.

Single phase charging is limited to about 13kW AC which puts us in 55A region (AC side) unless I mistaken.

On the DC side this is about 250A on the busbar, and roughly 50A per battery (I hope your batteries are rated 1C) as this puts 0.5C batteries on the limit. 

You could easily wire batteries with 35mm2 cables and 120A fuses to the busbar.

Wire the busbar to the inverters with 50mm2 and 160A fuses. 

The keto fuses do not blow easily and will allow the occasional surge over the limit. Personally I would not install circuit breakers.

Just to be clear you intend to charge your EV from batteries... not from grid or solar? If it from grid or solar then this setup can be simplified considerably

 

Initially when I sized my system I also looked the max current and I ended up installing 95mm cables (thinking about charging cars and installing a huge battery when ev batteries get scrapped for home storage), those cables are probably the coldest part of the system and I call them my heat-sinks, the are used to keep the system "cool". Good luck with your system, post pictures! With such big currents be sure to do load tests and make sure there are not hot spots on the system

Posted
17 minutes ago, Frankista said:

My current busbars in the combiner box are of 24 mm wide and 4 mm thick

Made out of what metal? They sound a bit lightweight to be honest. Look at the real busbars below in this thread (that is what I would use for 500A)

 

 

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