Deye energy source priority setting

Hello,

I am planning to build a 6 kW hybrid solar system that would have 48V batteries and also export excess energy to grid.

I am currently researching which inverter to choose and I am tempted to go with Deye.

However, after reading the manual and forums as well as watching a lot of youtube videos it is still unclear to me if priorities can be set up such that:
1) if solar is available use that first
2) if no solar (night), then use only batteries (until a low threshold is reached)
3) only as a last resource use the grid
4) in all cases, excess solar should be exported to grid
5) never use grid to charge batteries

Some other chinese inverters like the Easun have the SBU mode (solar-battery-utility priority) which is pretty self explanatory, but for the Deye I'm having a hard time figuring out if an equivalent setup can be achieved.

I also see that Deye supports "non-essential loads" circuit that requires a CT as well as an "essential loads" circuit where the loads get connected through the inverter.
It is my understanding (correct me if I'm wrong) that the non-essential side would still consume at least a small amount of grid energy even if it is set to last priority as it would be necessary for the CT to record such a consumption before the inverter would adapt to force only solar/battery energy usage. In this case, am I right in saying that if I want truly 0 grid consumption I should just connect all loads (house, everything) to the "essential loads" circuit and just not bother with the "non-essentials" at all?

Thank you

ultrasbz said:

However, after reading the manual and forums as well as watching a lot of youtube videos it is still unclear to me if priorities can be set up such that:
1) if solar is available use that first
2) if no solar (night), then use only batteries (until a low threshold is reached)
3) only as a last resource use the grid
4) in all cases, excess solar should be exported to grid
5) never use grid to charge batteries

Click to expand...

That's how I'm using my Deye 12K. Just connect CTs close to your utility connection so that Deye can understand what is coming in from the grid or going out. Then set "ZERO EXPORT TO CT" and enable "SOLAR SELL". Adjust "ZERO-EXPORT POWER" around 40 so that Deye has better control over zero point (even 20 might be ok, but manual suggest 40-100 IRC). This means how many watts are allowed to flow in/out to Deye to know the precise zero point. The lower the value, the more difficult determining the zero point is.

Energy pattern is "LOAD FIRST" which means PV (if available) is always used before grid and excess PV will charge batteries. If there's even more PV available then it exported to grid.

In battery menu make sure "GRID CHARGE" is disabled.

If there isn't enough PV/battery Deye uses grid automatically.

Very happy with my Deyes so far.

Thanks for your reply!

A couple of questions:
1) Regarding the low battery threshold that would make the inverter switch to grid. Do you set it as a voltage or a percentage of the SoC? I know voltages can be problematic for LiFePO4 due to the flat discharge curve where 30% and 80% can be about the same voltage. On the other hand, for SoC percentages you need to have communication between the inverter and battery BMS, and I've heard that even popular BMS's like the JK BMS isn't always very accurate and can suffer from drift. It seems that in terms of SoC the consensus is the Victron Smart Shunt is the best but then I don't think it can be connected to the Deye to let it know the SoC. What is your setup in this regard?

2) The english translation of a lot of these settinga are a bit confusing, for example "zero export to load/ct" and "solar sell" seem to be contradictory, but apparently can be used together. As for the "zero export power" value, do you think it even matters if it is 0 or 20 or 40 if "solar sell" is enabled? I got the impression it is a small amount of energy we intentionally take from the grid to avoid tripping sensitive meters when we are not allowed to feedback to grid, but in my case I do want to do that and with "solar sell" enabled I'm thinking of setting it to 0 to avoid any unnscessary consumption from the grid, especially at night.

ultrasbz said:

Thanks for your reply!

A couple of questions:
1) Regarding the low battery threshold that would make the inverter switch to grid. Do you set it as a voltage or a percentage of the SoC? I know voltages can be problematic for LiFePO4 due to the flat discharge curve where 30% and 80% can be about the same voltage. On the other hand, for SoC percentages you need to have communication between the inverter and battery BMS, and I've heard that even popular BMS's like the JK BMS isn't always very accurate and can suffer from drift. It seems that in terms of SoC the consensus is the Victron Smart Shunt is the best but then I don't think it can be connected to the Deye to let it know the SoC. What is your setup in this regard?

2) The english translation of a lot of these settinga are a bit confusing, for example "zero export to load/ct" and "solar sell" seem to be contradictory, but apparently can be used together. As for the "zero export power" value, do you think it even matters if it is 0 or 20 or 40 if "solar sell" is enabled? I got the impression it is a small amount of energy we intentionally take from the grid to avoid tripping sensitive meters when we are not allowed to feedback to grid, but in my case I do want to do that and with "solar sell" enabled I'm thinking of setting it to 0 to avoid any unnscessary consumption from the grid, especially at night.

Click to expand...

1) I'm using % as my batts are communicating with Deye. I am grid tied so I let Lifepos to go down to 5% and let them stay there untill the sun shows up next time which might take days/weeks up here in winter. LFP chemistry is more than fine with 5% to 100% SoC (~3,0V to 3,5V), so I don't need any shunt to calculate the real SoC as I only care about empty or full SoC. I might be more interested in what happens between if I'd be totally off-grid.

2) You'll learn how smart Deye is, once you start to use it. "Zero Export to CT" means that any power is never flowing back to grid, only your loads are taken care of. You need external CTs to do this (=to tell Deye where is the arbitary line between grid and your loads). If you don't enable "Solar Sell" it never sells even excess PV to grid. In your case, you should enable it. This way Deye uses power (batt/PV/gen) for your loads only, but can still sell excess PV, and only excess PV to grid.

The closer to zero you set "Zero Export Power" value, the more power fluctuation to/from grid there will be as Deye has to correct itself always late. I bet 20 or maybe even 10 is ok for Deye to always know if power is flowing in or out. My setup is so big that 40 or even bigger value wouldn't make any difference what so ever.

shadowmaker said:

1) I'm using % as my batts are communicating with Deye. I am grid tied so I let Lifepos to go down to 5% and let them stay there untill the sun shows up next time which might take days/weeks up here in winter. LFP chemistry is more than fine with 5% to 100% SoC (~3,0V to 3,5V), so I don't need any shunt to calculate the real SoC as I only care about empty or full SoC. I might be more interested in what happens between if I'd be totally off-grid.

2) You'll learn how smart Deye is, once you start to use it. "Zero Export to CT" means that any power is never flowing back to grid, only your loads are taken care of. You need external CTs to do this (=to tell Deye where is the arbitary line between grid and your loads). If you don't enable "Solar Sell" it never sells even excess PV to grid. In your case, you should enable it. This way Deye uses power (batt/PV/gen) for your loads only, but can still sell excess PV, and only excess PV to grid.

The closer to zero you set "Zero Export Power" value, the more power fluctuation to/from grid there will be as Deye has to correct itself always late. I bet 20 or maybe even 10 is ok for Deye to always know if power is flowing in or out. My setup is so big that 40 or even bigger value wouldn't make any difference what so ever.

Click to expand...

There are two different setting pages to setup "Shutdown", LowBat", "Restart", which is the right one to indicate when the inverter will start to take energy from the grid and finally to stop ?

Default values (ish). 10% 20% 35% i got on mine. Or similar in volts (as I am running).
I am not using BMS comms.

matvox said:

There are two different setting pages to setup "Shutdown", LowBat", "Restart", which is the right one to indicate when the inverter will start to take energy from the grid and finally to stop ?

Click to expand...

IRC if you choose battery style as "lithium" only upper setup page is available, but with "battery V" or "battery %" only lower setup page is available.

I'm actually having trouble to get my cheap rack batteries to go down to 3.0V/cell (=safe empty level) even though I have set both "shutdown" and "lowbatt" down to 3%. My batts are communicating with Deye (closed loop) which means BMS is actually controlling Deye. For some reason BMS won't let my batts to discharge under 3,17-3,2V (Deye usually shows 7-9%). I have tried to find reason for it in BSM parameters (using BSM tool), but haven't found anything so far.

In order to prioritize the use of PV - Battery - and Grid as last resort, and no charging using Grid, go to System Work Modes - Time Of Use, and just enable Time of use. Untick everything else under Grid or Gen. That's it

Hello , what settings should I have if I want that when grid is on during the day it should export and when grid is off during day it should charge batteries ? Thanks

I would set it up to Load first, then the PV surplus would charge the batteries and then the leftover should be sold to the grid if you have an export agreement with your PoCo.

LydMekk said:

I would set it up to Load first, then the PV surplus would charge the batteries and then the leftover should be sold to the grid if you have an export agreement with your PoCo.

Click to expand...

Thanks but I want to export first when grid is available as we have curtailment here let us say if grid is Available from 11to 3 want to export and from 3-6 I want it to charge batteries ?

ultrasbz said:

Some other chinese inverters like the Easun have the SBU mode (solar-battery-utility priority) which is pretty self explanatory, but for the Deye I'm having a hard time figuring out if an equivalent setup can be achieved.

Click to expand...

You are not alone - or were not alone, I am trying to do the same thing and having issues. Have you managed to work it out?