Home ESS between Rennes and Fougeres, France

[pkannoglou (Pierre)]

Hello

I started with AC-coupled PV Hoymiles inverters for self-consumption, under the regimen the french grid operator allows (Enedis CACSI) up too 3000Wc without too muchn paperwork, which I admin I’m not very fond of.

First 1500Wc with 4 modules in early 2023

Then 3 additional modules bringing it to 2700Wc in late 2024

With this I have a DIY water heater PV router.

With the uprade I ended up with PV excess I could not entirely shove into the water heater. Adding to that, my local grid has a below-average reliability that is unlikely to be a transient condition, the charm of living on the countryside.

So I took the dive and added an inverter :

• Multiplus-II GX 48/5000
• 2 Pylontech US5000 batteries

Final result with the MP-II besides the main electric panel

I had to cram all of this in a dwindling available space, as its placement had definitely not been something I had planned for when we renovated this house in 2021-2013, a refresh from bare stone walls with little else being kept.

I used Legrand DLP trunking to hide the cabling, with the added bonus that you can clip sockets on it, I used that to keep an RJ45 to expose the VE.Bus connector so I don’t need to remove the Multiplus cover to use VEConfigure with the MK3.

Hiding the cabling between this trunking and the MP cable glands needed a little improvisation, I used 20mm rigid conduit.

And to hide that, as well as the Multiplus power switch that’s way to exposed to mishaps, a custom made cache from a bent plastic panel.

The PV inverters remain AC coupled. Since Hoymiles is so far not certified by Victron (I hope they could be, someday not too far) there is a risk should they fail to timely limit / cut their power while off grid when the battery is fully charged.

I have considered the options of DC-coupling my PV, but the scattered locations, cable lenghts, made this unpractical and unreasonably expensive.

So, they remain AC coupled on the MP input side.
I have, however, added switches on the panel that let connect them on the MP output, under close supervision, in case of emergency, such as a long grid outage during day, to top up the batteries and see them through the outage without cutoff.

On the automation side, I’m really just starting, this system has been running less than 2 weeks.

Still looking at the possibilities of nodered, I was already planning to run one on my homeserver but having one directly on the GX controller is definitely a perk for availability.

Right now I have a flow for my water heater, which still needs improvement to work well with ESS.

What I’m looking for is to let any PV excess of the day go into the water heater until it’s charged, then let the excess be used by the ESS for the battery. Ideally, with the batterylife algorithm still kicking in when needed to raise the ESS active SoC.

I ran across this

es-ESS: Tiny tool belt for any ESS

Hey all, some months ago, I finished the migration to a victron-centric system, and started to dig into phython and the posibilities of venus os. I’m a professional software engineer with about 20 years of experience and therefore creating the second helpful script was no option - it had to become a service-based, modular tool belt to ensure maintainability during the (hopefully) next 10 years So, es-ESS was born. Every service works independent (with some dependencies) and can…

which is interesting but right now I’m not wanting to modify the OS without knowing where I’m going. It’s not as if I had a lab MP; if I screw the one I have I’ll have to deal with the outage while I reinstall it.
I am also keeping an eye on the memory usage of the MP-II GX board, since this model has only 512MB and with nodered loaded it’s already quite filled, that’s an additional factor making me wary of adding running services, third party or not, on the OS.

Well, while the hardware implementation is mostly done, I still have work to do to bring this system to expectations.

[yann (Yann Jautard)]

Belle installation ! Très propre, j’aime beaucoup votre solution pour cacher les tubes en bas de l’onduleur.

Pour le couplage AC, si vous n’êtes pas certain que les onduleurs se déconnectent bien en cas d’augmentation de fréquence, il y a la solution de les raccorder sur AC out 2, et de programmer le relais avec trois assistants pour couper AC out 2 si pas de réseau et soc>98% par exemple

[pkannoglou (Pierre)]

Il me semblait que la sortie AC2 déconnectait dès qu’on passe off grid.
La possibilité de commuter les onduleurs en aval est pour pouvoir recharger la batterie pendant une panne de réseau, avec la contrainte de surveiller et déconnecter à temps pour ne pas approcher la zone d’incertitude.
Je peux aussi faire ceinture et bretelles en réduisant la puissance des onduleurs par la DTU (j’ai une passerelle OpenDTU) quand off grid et que le SoC dépasse un seuil.
Même si je ne miserais pas entièrement dessus, car l’automatisme peut être défaillant et le dégât potentiel sur le multiplus est réel.

For those who wonder, this is about my setup to move AC coupled PV (hoymiles, not certified with victron) downstream of the inverter. The suggestion was to use the AC OUT 2, however I believe it always disconnects when off grid. And my aim is to be able to charge the batteries during long grid outages, with the constraint of keeping a close eye and disconnecting the PV from the inverter before the SoC is too high.
Another safety I could add is to limit PV power via OpenDTU when off grid and the battery Soc reaches a threshold. Though I’ve no intention to leave that unsupervised; if the automation for any reason, fails, the damage to the inverter can be very real.

[yann (Yann Jautard)]

Par défaut, le relais ACout2 est deconnecté si pas de réseau, en effet.

Mais il est possible de modifier ce comportement avec l’ajout d’assistants dans la programmation du multi.

Je m’en sert souvent pour piloter la résistance du chauffe eau en site isolé quand les batteries sont pleines.

[pkannoglou (Pierre)]

C’est bon à savoir.
Maintenant, comme je ne le savais pas, je n’ai pas prévu la place dans le tableau pour les disjoncteurs aval de AC2.
Si je veux rester cohérent, les disjoncteurs de protection de sortie du MP-II sont dans le tableau ESS, qui n’a plus qu’un module de libre; un 32A tiendrait, après ça passe généralement en 2 modules.
Réflexion à faire, si je peux exploiter cette sortie dans le circuit sans devoir faire un patch sale.

[BjoernK (Björn Kellermann)]

Bonjour @pkannoglou

you can integrate the Hoymiles with OpenDTU and OpenDTU-dbus. Each single inverter will show up. I have 4 hms and 1 hm running.

Factor 1:1-rules is satisfied, so you can connect the Hoymiles to AC-out. They continue during grid failure. You should configure frequency shifting. In case of 100% SOC, the MP2 increases frequency and the Hoymiles will reduce power linear until switch off. Double check the French grid code, but should be similar to German grid code referring ARN-4105. With OpenDTU, you can read out the grid parameters in your Hoymiles and you can see the frequency shifting events.

Frequency shifting is the official method to throttle AC-PV when off grid and each grid tied inverter must implement it.

You should add at least one MPPT to restart your system from sun during grid failure when SOC is 0%. This is named “black start”.

With current MP2 you can control AC-out2. Using relay assistant, you can open and close AC-out2 based on SOC to cut non-critical loads.

I use a Shelly for my water heater.

Have fun and enjoy the sun in your nice house!