Solis Hybrid inverter with DIY battery

Check or ask if you can use 14s configuration. Also verify that it can charge cells to higher voltage as none of using 18650 cell. I do not think it should be a problem but the firmware might restrict that. Pylontech protocol is not a show stopper as it does work with diferent protocol.

So, phenomenal progress this evening. I got my wee UART to CAN bus adapter, (about £5 on amazon), and I had a few ESP32 boards lying around. So I used the git repo in the second post on this thread and built a variant of what's in the repo diagrams, no display, no digital isolator (that the impatience in me). A few hours to get the sketch to compile, there's a particular version of the Daly UART lib that's needed. Guru Meditations (crashes) all over the place, but now I'm finally getting places.

This is with the battery set to User Defined, and it's successfully reading the SoC of the BMS though the CAN bus interface and displaying it on the inverter! It's also showing "CAN OK".

It's not doing much else at this stage, but I think this is a huge milestone for me, and I think I'm on the right road to getting my battery working with the Solis inverter, finally. :)

At this stage I've got my canbus bridge emulating user-defined, aobo (using SMA protocol), and Pylontech (I did the changes to give the correct name and the metrics in the right places according to the pylontech doc above), and I'm still not getting current pulled from the battery. I've verified the battery with a resistive load and can easy pull 10A from the BMS, app shows info fine. Just not working with the Solis no matter what I try.

Here's a quick update now that I have the battery working. I was able to get the battery charging at night between 2-4am (1/4 price night rate), as well as topping up the immersion without interrupting each other. All pulled from the grid, then at 4am switched back to powering the house from the battery. :)

On the charge slope, I believe that's the charge curve of the battery, CVCC, so once it gets to the target voltage, it ramps down the current till it gets to 0.5c rate, at which point it's charged. On my tariff, 2am to 4am is the 1/4 price rate (7.5c/kWh). Anything outside that is 1/2 price rate (15c/kWh till 8am). You might be right on moving the Eddi boost time. I'll try boosting immersion closer to use time, but each unit later in the night costs double, so I'd only want to put it on for half the time, and see if it ends up at the same temperature. I'll give it a go. Yes, Eddi for the immersion.

Wait. Is anyone complaining of cold showers? Interested for when I am forced to smart meter. ATM I'm day night so I boost the last hour and no one has issues with hot water.

But I'd try what you have setup to save max money if it stil provided comfortable showers

Not so far, decent showers in the morning, but I'd estimate I'm only getting about 3-4kWh of energy into the cylinder. I have 4 temp sensors attached to it, and the bottom never gets much about 20degC, where the top sensor shows about 63degC. Thinking of longer immersion element or getting a willis immersion fitted. I've been told that I could get much more energy into the cylinder that way, up around 6kWh, so a lot more hot water that way. Current setup is not circulating water at all, so it's all sitting at the top. The average of all the sensors drops from about 44devC to 42degC between 4am and 8am.

Good suggestion, I'll look into a destratification pump as well. Eddi wired into both sink and bath elements, it's definitely set to bath, the sink setting heats far less. My problem in controlling the pump from the eddi is that it's downstairs in the utility, whereas the cylinder is upstairs, and I've no easy way of running a cable to the pump from the Eddi.

Why are you charging overnight then when there is plenty juice in the battery and we have sunny days? I only charge at night if battery is low and also based on solcast forecat for the day.

I think you've got the math wrong there meelick. Most batteries have a lifetime duration in the 6,000-10,000 range. Assuming you (fully) cycle the battery everyday that's 365 times a year. So you're looking at ~20 years for some batteries. Even at that even at the end of the published lifetime, the battery isn't dead, just that it will perform at (say) 70% of the initial performance.

Batteries are there to be used - that's why you bought it.

Missed the connection there alright. Yeah that makes a bit more sense now....

What make is the battery? Unless it's listed in the Solis you'd have to use userdefine and then enter the parameters from the spec sheet of the battery bank.