Hi all
I’ve been looking to connect our Solarfocus solar thermal system to HA, probably by retrofitting some sort of networked controller such as this one - Solar Control V2 Wifi - Levtech Service & Production
But I can’t see anyone working on such a project. Am I just rubbish at searching or is no one working on such a thing?
NB I’m not talking about PV, already got that connected.
NB2 - by solar thermal I mean the type of system typically used to heat hot water for domestic use, not space heating.
Any thoughts gratefully received!
1 Like
Hi Steve - fairly new to Home Assistant and probably can’t be much help to you straight away. However, it sounds like we may be working on the same issue from different directions.
I have a Tesla Powerwall / Gateway 2 / Solar installation and have just installed an immersion heater switch (a Timeguard model FSTWIFITU) that operates via Tuya.
Setting up the Tuya integration was a bit convoluted but I got there in the end and can now switch it on and off from within the dashboard.
Next step is to set up an automation that senses when the Powerwall starts exporting to the grid and then switches on the Immersion Heater. I’ll need to use a timer to ensure that it doesn’t repeat for a set period.
Only issues I have at the moment are:
- Not sure which entities are the most useful for detecting this.
- The weather has been really poor since I did my initial configuration so I can’t get any hints from the logs or entity properties to pin down the above.
I’m sure I will get to the bottom of this (a little surprised I couldn’t find an existing solution for this) and would be happy to trade notes with you - if I’ve interpreted your post correctly.
Hi Steve
I have two automations on my system now. First one detects Powerwall charging stopping and if export to the grid exceeds 1kW, it turns on the Immersion heater for 30 minutes. It then waits 2hours before it can be triggered again:-
alias: Auto Immersion Heater on Grid Export
description: ""
trigger:
- platform: state
entity_id:
- binary_sensor.powerwall_charging
from: "on"
to: "off"
condition:
- condition: numeric_state
entity_id: sensor.powerwall_site_now
below: -1
action:
- type: turn_on
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
- delay:
hours: 0
minutes: 30
seconds: 0
milliseconds: 0
- type: turn_off
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
- delay:
hours: 2
minutes: 0
seconds: 0
milliseconds: 0
mode: single
2nd one just ckecks the Powerwall charge at 6.30am and if above a threshold (35), should switch on the immersion to heat up the water before the gas central heating would (Gas boiler water temperature is less than immersion heater). I am not completely sure if the 35 should be 35 or 0.35 as the Powerwall charge is given as % and I don’t know yet how the percentage value is actually handled.
alias: Turn on Immersion if Good Morning Powerwall Charge
description: ""
trigger:
- platform: time
at: "06:30:00"
condition:
- condition: numeric_state
entity_id: sensor.powerwall_charge
above: 35
action:
- type: turn_on
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
- delay:
hours: 0
minutes: 30
seconds: 0
milliseconds: 0
- type: turn_off
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
mode: single
It turns out that the first routine to turn on the immersion when charging stops and the gateway starts exporting more than 1kW wasn’t robust enough. Occasionally this triggered before the Powerwall was fully charged. I altered it to the following to include a check that the Powerwall was at least above 98% 
alias: Auto Immersion Heater on Grid Export
description: ""
trigger:
- platform: state
entity_id:
- binary_sensor.powerwall_charging
from: "on"
to: "off"
condition:
- condition: and
conditions:
- condition: numeric_state
entity_id: sensor.powerwall_charge
above: 98
- condition: numeric_state
entity_id: sensor.powerwall_site_now
below: -1
action:
- type: turn_on
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
- delay:
hours: 0
minutes: 30
seconds: 0
milliseconds: 0
- type: turn_off
device_id: 78a1b94336b83e488259c0c75893dbed
entity_id: switch.immersion_heater_switch_1
domain: switch
- delay:
hours: 2
minutes: 0
seconds: 0
milliseconds: 0
mode: single
Many thanks Kevin and sorry for my very slow response.
The issue I’m trying to address is about solar thermal systems, not the heating of water via an immersion switch powered by PV.
We have this system - CPC Solar Collector
(We also have PV and powerwalls but automation options seem a bit more plentiful for those)
2 Likes
It is something I’ve toyed with doing, the basics are fairly simple connect two PT1000 temperature probes and a output relay. If the collector temperature is a configurable number of degrees hotter than the tank temperature turn on the pump relay, unless the tank already is at the desired temperature. I have a Steca TR301SC on mine.
A few advanced features are that if the collector is at risk of freezing the pump turns on to move some heat back to the collector. Plus a holiday mode will actually cool the tank overnight so the collector temperature is less likely to boil (the system I have is pressurised so it boils at ~120deg C). I don’t know what the Levtech’s issues and alerts are, nor what their pump saver is actually doing.
This is all within the bounds of an ESPHome project on a cheap ESP8266 board.
You already have WiFi visibility which mine doesn’t. What more would doing it yourself add?
hi Steve,
Try to take a look at this:
https://github.com/LavermanJJ/home-assistant-solarfocus
I’ve integrated a Resol Solar Thermal controller into my HA setup. There is a good HACS integration for Resol that exposes the sensors, pumps, power meters etc. It works well. Only recently changed to HA, so still working it all out. This is the Resol dashboard that I’d like to have as a HA card at some point:
