My DESS system:
Running DESS and it works properly. But when the energy prices go below “0” the MPPT’s keep on working. At that time they COST instead of SAVING money. Imho they should shutoff at that moments.
Using Home Assistent I managed to shutoff the Goodwe Inverter; that works perfect.
How do you guys shutdown the MPPT’s?
via modbus …
2 x 150/45 + 1 x 150/35 via VE Direct to USB
com.victronenergy.solarcharger Charger on/off Register 774
Manually or automatically?
Both would be possible … but I do this automatically when I reach a certain SOC … unless I’m aiming for balancing … then via a time value
Using NodeRed?
I myself use the Siemens Logo 8 series for external Stuff like Switches or Sensors etc. , but I think Home Assistant can also ‘speak’ Modbus …
You also could use :
com.victronenergy.settings
Feed excess DC-coupled PV into grid
Register 2707
0=Don’t feed excess DC-tied PV into grid; 1=Feed excess DC-tied PV into the grid
to activate or deactivate the Mppt/DC Feed to the Grid …
Hi,
Why would you want the MPPT’s to shutdown, and therefore stop powering your domestic / micro-grid loads, therefore importing power or drawing down from the battery bank?
I am assuming that although the export tariff you have is <= £$0, the import tariff remains > £$0?
What was your import cost in total for the last 12 months?
Surely you want to simply stop exporting to grid, and use your free solar input to power the domestic / micro-grid loads at that point, retaining your battery SoC at 100%, until the export tariff is > £$0?
This means batteries remain at 100% SoC (ready to discharge from that point when no solar input is available). The MPPT’s should be providing only enough power for domestic/ micro-grid loads, certainly in my setup my CerboGX throttles my MPPT’s after 100% SoC to do this and even round robins the MPPT’s work cycles.
My first thought would be to increase battery storage to harvest that excess, for use when the import tariff is > £$0, and /or to export the excess harvested energy when the export tariff is > £$0.
@anon39974850:
Well, my PV-system generates approximately 15000kWh each year.
I use around 10000kWh each year. Taxes in the Netherlands are around 0,15-0,18 euro per kWh. But there is a strange legislation which says that you may cancel out the taxes of the electricity you earned from the grid to the electricity you feed into the grid. (and yes: This legislation is fantastic but perverse 
)
In my case I make my calculations without taxes because I don’t pay them (because my feed in is higher than the amount I get from the grid).
So to refer back to my first post: It costs me money when my PV-system generates electricity during the negative prices. It that case I can earn money to use electricity from the grid and charge my batteries.
I thought this may have been the case. I discussed this with a friend who’s daughters BF is Dutch, and her father has something similar. Our feed-in system in the UK isn’t as good. You can get paid to export, but get nothing to import.
My friend uses a contactor to disconnect the grid based on a set of rules, mainly around battery SoC and solar forecast and tariff.
Would the lastest VenusOS 3.60 be of any help in this situation. I haven’t had time to go through all the detail yes but they are ESS / DESS improvements (only applicable if you use a GX or similar device).
How do you get the current pricing tariff real-time for you import/export charging?
This update in V3.60 probably relates to what you want to do:
The ability to control an MPPT relay, via Node-Red on a GX. So you could disconnect an MPPT using the relay, triggered by a NOde-Red rule.
Just upgraded to Venus OS V3.60 but the behaviour stays the same; MPPT’s don’t shutdown during pricing <0.
The system gets the pricing itself (I think by ENTSO-E afaik). But I don’t think the “problem” is there.
I think the Victron Engineers didn’t taken in account the “strange” tax-situation in The Netherlands. That’s why I want to create a workaround. So anyone who can help me with that?
As Victron is based in the Netherlands, I’m sure the engineers are fully aware of the situation. But it might be worth reaching out to Victron support.
I don’t use Node-Red, as I’m favouring Home Assistant. I see from this post: Make DESS aware that PV can be turned off when prices are negative - #4 by ErikBTD
that you can use HA. Why not simply use MQTT to turn off the MPPT controllers when pricing is negative in the same way you do with the PV Inverters you have? The required register and values can be found in the Victron documentation, do a search for ModBus registers or similar.
I think it might mean setting the MPPT mode to 4 (off), you’d need to look into this further.
Hi @ErikBTD ,
Read this thread: Use MQTT to enable/disable SmartSolar MPPT - VictronEnergy
I’ve tested using MQTT explorer and Home Assistant (you’ll need to have HA running as HAOS and MQTT addon enabled ) and I can turn a MPPT controller off or on via each.
So I assume now all you’ll have to do is edit the current automation you have for your PV inverters to also include turning off /on the MPPT controllers.
EDIT: The payload needs to be JSON formatted e.g.: {“value”:4}
So, I tried to adapt my automation. But it doesn’t seem to work.
The automation it triggered right.
Working MQTT local based.
But for some reason the message does not change de “mode” of the MPPT. (as I can see in MQTT explorer.
What am I doing wrong?
(BTW: I never used MQTT before)
Have you setup MQTT on your Cerbo?
Can you publish the MQTT command via MQTT Explorer?
So MQTT is switched on in the Cerbo
I see a lot of messages in MQTT Explorer:
When I publish in MQTT explorer:
also the Mode does not change.
The payload needs to be JSON formatted:
{“value”:4}
You need to publish to the MQTT write queue:
W/[YOURCERBOINSTALLID]/solarcharger/[DEVICEINDEX]/Mode
NOTE the ‘W’ at the start of the topic path!!!
@ErikBTD You may want to edit your previous post to remove references to you CERBO installation ID?
Yeah, you’re right! Just removed my CERBO ID.
Just found out that I can change MPPT mode in MQTT Explorer; so that works!
Just tried to publish a package but is seems to be the client is not connected.
How can I get this client connected?
Have you added and setup the HA MQTT integration?
Screenshots?
Nudge…
