Why the SunSynk inverter automation for Octopus Flux is emptying your battery

[klondike]

Quick Intro

A brief word for any visitors who may find this post...

LetsChat is a forum primarily intended for friendly pensioner chat. Full members will see more boards than casual visitors or new members. You may or may not have any interest in that but perhaps you know a pensioner who may like to join us - if so please send them a link to https://letschat.club/ Should they join us they will be made very welcome.


The SunSynk Octopus Flux problem

One feature that may draw people to the SunSynk range of inverters is that they feature an automation intended for use with the popular Octopus Flux tariff. During the bright days of summer this will probably work well but sometimes you will find with dismay that it has emptied your battery leaving you needing import at the day rate until 2:00am when the next cheap import period opens.

Why the automation fails

Once you have gone through the SunSynk app setting up your inverter for Octopus Flux you will see that by default it has set up a 16:00 to 19:00 time slot which is the standard Octopus Flux high export return period along with a short 5 minute slot after that.

You should also have specified a minimum state of charge after the exporting has completed to last you around til the cheap import period at 2:am next day.

So long as your battery has enough energy in it when the export period begins to continue exporting until the end of the export slot all will be well. If not then the inverter will still be running the Selling first work mode which the automation set. Your inverter will continue to export until the maximum discharge level is reached then you will be running your load from any remaining PV solar from your panels maybe plus the expensive 16:00 - 19:00 grid import and soon after for sure the day rate import. I have seen reports that the inverter briefly stops exporting and starts again although I have not seen that happen myself.

SunSynk response

Sunsynk support admit that the automation fails but point out that it is Beta software
When will it be fixed? ASAP
What is the timescale? ASAP
What can I do in the meantime? Run it fixed price or Octopus Agile
Translation - It's bust and don't hold your breath for us to do anything to fix it

Ways around the problem
The solution many will choose is going to be third party software maybe Solar Assistant or Home Assistant or maybe both.

There is a manual get around which will not be attractive. You can use a solar forecast app and daily adjust the start time of your export to not be complete by the end of the period. You will still need to be able to set no export should your guess turn out to be wrong.

You can just let the inverter follow the fixed price routine where it exports excess solar once the battery is full which makes the cheap rate overnight charge partly pointless as overnight import costs more than day rate export so you may as well switch to Octopus Export tariff which will lose you your cheap import,

These options will almost certainly lead to a lower rate of return.

Solar Assistant

This is going to be the simplest fix for most people. You will need to get cables to attach the inverter to your Solar Assistant machine which can be a Raspberry Pi or just buy a pre-configured machine direct from Solar Assistant.

Fitting the cables involves removing the small front panel. You may wish to power the system down while doing that.  Should you need the splitter cable as your inverter combines RS485 and the battery CAN in a single RJ45 socket be aware that space is limited.

You can replace the WiFi dongle instead but I consider that to be unwise - it means that SunSynk and your Installer can no longer access your inverter should you need support. The SunSynk all will no longer work either.

I chose to use a Pi5 with a damaged USB port I already had. If you have no Pi you may as well just buy the machine from https://solar-assistant.io/shop although it will cost a bit more.

I am finalising Solar Assistant automations that can be used to control import based on the Solar prediction in Solar Assistant (currently Beta but seems to work OK) and forced Export. Both try to be as cost effective as possible to maximise return. The Automations will be documented in other posts and may well be there by the time you read this;

Home Assistant

If you are unfamiliar with Home Assistant be aware that there is a learning curve.

Anybody that knows Home Assistant probably won't be reading this. If you are you may find running it together  with your Home Assistant may make things easier as Solar Assistant will communicate with the inverter and communication between your automations and Solar assistant is handled by MQTT.

Guest posts on the topic may be made here - https://letschat.club/index.php?board=28.0