Hi all

Recently got the Sunsynk Inverter, batteries and panels installed and also added on the SolarAssistant and HomeAssistant combo.

Entire house was installed on essential load and have the geyser on an Astute timer.

During the day, I notice that after the batteries have charged up fully from solar, the PV energy is limited by the current load which makes sense since we cant feed back into the grid.

The idea I had was to set up an automation on HA whereby if the batteries are fully charged and there's enough PV energy(e.g. >3kW), to automatically switch on the geyser (has an electric blanket). This way, the water will remain warmer for longer and when the timer switches on the geyser in the morning it should theoretically use less electricity to heat from batteries/grid when there isn't enough sunlight as yet.

Does anyone know how I could possibly go about setting this up?  There doesn't seem to be a full PV energy counter from the inverter in SolarAssistant to determine if there's enough PV energy to supply the geyser prior to it being limited by inverter.

Thanks for any assistance.

27 minutes ago, shylo229 said:

Hi all

Recently got the Sunsynk Inverter, batteries and panels installed and also added on the SolarAssistant and HomeAssistant combo.

Entire house was installed on essential load and have the geyser on an Astute timer.

During the day, I notice that after the batteries have charged up fully from solar, the PV energy is limited by the current load which makes sense since we cant feed back into the grid.

The idea I had was to set up an automation on HA whereby if the batteries are fully charged and there's enough PV energy(e.g. >3kW), to automatically switch on the geyser (has an electric blanket). This way, the water will remain warmer for longer and when the timer switches on the geyser in the morning it should theoretically use less electricity to heat from batteries/grid when there isn't enough sunlight as yet.

Does anyone know how I could possibly go about setting this up?  There doesn't seem to be a full PV energy counter from the inverter in SolarAssistant to determine if there's enough PV energy to supply the geyser prior to it being limited by inverter.

Thanks for any assistance.

Normally not very easy to measure when you have more than 3kW of PV. 

What if you do have more than 3kW and the battery is full and someone switches on a hairdryer, kettle or vacuum cleaner. This will then suddenly use PV and you no longer have the 3kW you want for the geyser? 

Now you have to start monitoring all the high power loads in order to stop sending power to the geyser? 

4 minutes ago, Scorp007 said:

Normally not very easy to measure when you have more than 3kW of PV. 

What if you do have more than 3kW and the battery is full and someone switches on a hairdryer, kettle or vacuum cleaner. This will then suddenly use PV and you no longer have the 3kW you want for the geyser? 

Now you have to start monitoring all the high power loads in order to stop sending power to the geyser? 

That is a very good point. The general load throughout the day is around 600W and the likelihood of any high power devices being switched on is extremely slim.

To start somewhere though, I'd like to see if I can even get this to work just based on the simple approach of having enough excess energy to account for the geyser.

After that, I would look to add on the functionalities to account for what you mentioned, be it looking at spikes in power, how long those spikes run(timed use cases), day of the week, existence of grid power, battery percentages, etc. 

I have an overly complex set up in Node-Red:

First a load controller to turn off all optional high load appliances once inverter load exceeds 7500W, and only restore them when below 3500W for 30s.

Geyser only turns on if inverter load is below 4000W.

The various boost programs:

To (1) get basic operating temperature from PV as soon as practical, and once battery is nearly full, put whatever excess there is into the geyser.

Measure available power by simply turning on the geyser and see how much battery draw there is after 10s...

 

PS - below 95% SOC (unless your battery is really fubar), you can be pretty sure that all excess PV production is going to battery charging - so you can measure your battery charge power to determine how much PV is available.  You only need to get creative when then battery is very nearly full and charge current tapers off.

Put the geyser on the Aux output of the inverter and install a smaller element.

Edited April 3, 20231 yr by frivan

25 minutes ago, JustinSchoeman said:

I have an overly complex set up in Node-Red:

First a load controller to turn off all optional high load appliances once inverter load exceeds 7500W, and only restore them when below 3500W for 30s.

Geyser only turns on if inverter load is below 4000W.

The various boost programs:

To (1) get basic operating temperature from PV as soon as practical, and once battery is nearly full, put whatever excess there is into the geyser.

Measure available power by simply turning on the geyser and see how much battery draw there is after 10s...

 

This is really cool. Looks like I'm going to have to learn about Node-Red first. I'm assuming there isnt a copy, paste and change a few naming config solution for this?

 

21 minutes ago, JustinSchoeman said:

PS - below 95% SOC (unless your battery is really fubar), you can be pretty sure that all excess PV production is going to battery charging - so you can measure your battery charge power to determine how much PV is available.  You only need to get creative when then battery is very nearly full and charge current tapers off.

I have the Sunsynk 5.32 kW batteries but noted. Thanks.

It is very much application specific, but you may be able to copy/paste some bits from my flows:

https://github.com/justinschoeman/node_red_sunsynk

6 minutes ago, JustinSchoeman said:

It is very much application specific, but you may be able to copy/paste some bits from my flows:

https://github.com/justinschoeman/node_red_sunsynk

I think the repo is private. Getting a 404 when trying to access it.

16 minutes ago, frivan said:

Put the geyser on the Aux output of the inverter and install a smaller element.

From what I've read on the forum the Aux port doesn't seem to work quite well for most people and it drains from the batteries instead of directly using the solar.

A simple one would be to say:

If the time is between 11:30 and 2:30
and battery SOC > 75%
turn on geyser [for 2 hours]
else 
leave geyser off

you should be able to do this with the front-end automations quite easily

2 hours ago, shylo229 said:

Hi all

Recently got the Sunsynk Inverter, batteries and panels installed and also added on the SolarAssistant and HomeAssistant combo.

Entire house was installed on essential load and have the geyser on an Astute timer.

During the day, I notice that after the batteries have charged up fully from solar, the PV energy is limited by the current load which makes sense since we cant feed back into the grid.

The idea I had was to set up an automation on HA whereby if the batteries are fully charged and there's enough PV energy(e.g. >3kW), to automatically switch on the geyser (has an electric blanket). This way, the water will remain warmer for longer and when the timer switches on the geyser in the morning it should theoretically use less electricity to heat from batteries/grid when there isn't enough sunlight as yet.

Does anyone know how I could possibly go about setting this up?  There doesn't seem to be a full PV energy counter from the inverter in SolarAssistant to determine if there's enough PV energy to supply the geyser prior to it being limited by inverter.

Thanks for any assistance.

Hi @shylo229 

Two things, what size Inverter have you got and what size is the element in you geyser? 

A few suggestions to think about.

You may want to consider dropping to a 2kw element if you have a 5kw, otherwise you start flying pretty close to the sun (aka system overload)

In my house, hot water is not counted as non-essential 🙂, as a result we heat it whether the sun is out or not. We obviously prefer to use solar power if it is available. 

You could set the smart switch to switch on the geyser at around 13:00 and run it till 15:30 (or by whenever your battery is reaching a good SOC).

If you set you mode timer settings and your priority load/battery setting  for your battery appropriately, if the battery is sufficiently charged by say 13:00 to reach your mode timer settings it will use the extra power to heat the water, otherwise it will use grid power as it will not have reached the desired SOC yet. 

Only automation you then might want to do is one to switch the geyser off if the SOC is less then 80% and power production is less than 3kw. 

You can increase the efficiency of hot water storage by installing a blanket and set your geyser for as hot as possible so that it heats up using the solar power during the day and then has enough stored heat to still be warm enough for the next morning. 

8 hours ago, shylo229 said:

From what I've read on the forum the Aux port doesn't seem to work quite well for most people and it drains from the batteries instead of directly using the solar.

It is true that the Aux drains from the battery but I would set it such that it only switches on above 95% and off below 85% SOC. You then need a second timing method to only switch the geyser on at a time that peak solar should be available... sat 11:00. Good luck with another control philosophy.

21 hours ago, Sc00bs said:

Hi @shylo229 

Two things, what size Inverter have you got and what size is the element in you geyser? 

A few suggestions to think about.

You may want to consider dropping to a 2kw element if you have a 5kw, otherwise you start flying pretty close to the sun (aka system overload)

In my house, hot water is not counted as non-essential 🙂, as a result we heat it whether the sun is out or not. We obviously prefer to use solar power if it is available. 

You could set the smart switch to switch on the geyser at around 13:00 and run it till 15:30 (or by whenever your battery is reaching a good SOC).

If you set you mode timer settings and your priority load/battery setting  for your battery appropriately, if the battery is sufficiently charged by say 13:00 to reach your mode timer settings it will use the extra power to heat the water, otherwise it will use grid power as it will not have reached the desired SOC yet. 

Only automation you then might want to do is one to switch the geyser off if the SOC is less then 80% and power production is less than 3kw. 

You can increase the efficiency of hot water storage by installing a blanket and set your geyser for as hot as possible so that it heats up using the solar power during the day and then has enough stored heat to still be warm enough for the next morning. 

Hi @Sc00bs

I have a 150L geyser and it has a 3kw element if I'm not mistaken so still well within range of the 8kw inverter. Haven't seen the inverter go past 5kw since it was installed. Also, the geyser does have blanket for heat retention as you recommended.

With my setup the entire house is wired only to essential load so I don't think priority load setting would work through the inverter unless I end up rewiring. Would rather go with a more software controlled option.

I was trying to avoid using the time related triggers during the day and go for a more "automated" approach since the weather has been kinda weird the past week or so but your explanation definitely gave me some ideas on how I could approach this. Will test out a mix of things and see what works.

Thanks!

@shylo229 what about something like Solcast to get readings regarding how much PV should be available in the next hour etc. 

 

https://github.com/oziee/ha-solcast-solar

 

I have a 2kW element in my geyser, and a custom controller based on a Geyserwise thermostat (just the thermostat) and a Sonoff THR320. The geyser is wired to the AUX port, but the sunsynk settings basically have it on permanently. When the Sonoff turns the element on between 16:00 and 08:00, I have Home Assistant turn off the "Use Timer" setting in my Sunsynk 8kW inverter, as well as setting the "Battery charge current" value to 0A. This allows the geyser to heat from the grid during the night without depleting the battery, but stops the battery from charging (or discharging) at the same time. Home Assistant also turns off the geyser when there is no grid power available, so that it doesn't deplete the batteries either. When the geyser is up to temperature and turns off the element, I set the "Use timer" back on, and the charge rate back to 50A.

So far it seems to be working well.

On 2023/06/06 at 11:38 AM, RoganDawes said:

I have a 2kW element in my geyser, and a custom controller based on a Geyserwise thermostat (just the thermostat) and a Sonoff THR320. The geyser is wired to the AUX port, but the sunsynk settings basically have it on permanently. When the Sonoff turns the element on between 16:00 and 08:00, I have Home Assistant turn off the "Use Timer" setting in my Sunsynk 8kW inverter, as well as setting the "Battery charge current" value to 0A. This allows the geyser to heat from the grid during the night without depleting the battery, but stops the battery from charging (or discharging) at the same time. Home Assistant also turns off the geyser when there is no grid power available, so that it doesn't deplete the batteries either. When the geyser is up to temperature and turns off the element, I set the "Use timer" back on, and the charge rate back to 50A.

So far it seems to be working well.

if i may ask, why did you use they Geyserwise thermostat? and did you get any other functions/reading from it besides the fact that it has the thermal cut off at 90deg?

or does this thermostat send a temperature reading to your the THR320? 

52 minutes ago, Flouw said:

if i may ask, why did you use they Geyserwise thermostat? and did you get any other functions/reading from it besides the fact that it has the thermal cut off at 90deg?

or does this thermostat send a temperature reading to your the THR320? 

I used the Geyserwise thermostat because it provides an analog reading of the actual temperature of the water, as well as the failsafe 90C physical cutout. I don't have easy access to the geyser (in my ceiling), and hot water is an "essential" in my house, as in most others, so I didn't want to play with solutions, and have to fiddle with them when they stopped working, etc, etc. The Geyserwise was thoroughly tested by the manufacturer, so I felt fairly comfortable using it myself. Also, it was cheap - R260 or so.

The downside being that it was analog vs digital, and I had to work to interface it to the Sonoff.

11 minutes ago, RoganDawes said:

I used the Geyserwise thermostat because it provides an analog reading of the actual temperature of the water, as well as the failsafe 90C physical cutout. I don't have easy access to the geyser (in my ceiling), and hot water is an "essential" in my house, as in most others, so I didn't want to play with solutions, and have to fiddle with them when they stopped working, etc, etc. The Geyserwise was thoroughly tested by the manufacturer, so I felt fairly comfortable using it myself. Also, it was cheap - R260 or so.

The downside being that it was analog vs digital, and I had to work to interface it to the Sonoff.

thanks for the response. would the Sonoff TH Elite not be a easier solution? as the temp probe would integrate much easier with the device itself. im poking around to see how i can also get the geyser on the "clever" side of things. to schedule  it. its also an essential in my home. thus not even connected on the inverter at this stage. but when i expand on the next phase, the geyser will be added, and would like to have some data to work with when it gets to that point. 

2 hours ago, Flouw said:

thanks for the response. would the Sonoff TH Elite not be a easier solution? as the temp probe would integrate much easier with the device itself. im poking around to see how i can also get the geyser on the "clever" side of things. to schedule  it. its also an essential in my home. thus not even connected on the inverter at this stage. but when i expand on the next phase, the geyser will be added, and would like to have some data to work with when it gets to that point. 

The Sonoff THR320 is almost identical to the THD320 (aka TH Elite). As far as I am aware, it just adds a display, which is not much use up in the ceiling! Both are only compatible with digital 1-Wire sensors like the DS18b20, etc. Unfortunately, the data pin is connected to GPIO25, which is technically an ADC-capable pin, but resides in the ADC2 group of pins (pins connected to the second ADC controller), as opposed to those in ADC1. And ADC2 is unusable when the WiFi peripheral is being used, according to the ESP32 datasheet. Which left me trying to figure out how to make the analog thermostat compatible with the digital Sonoff. Hence the little interposer board.

An alternative might be to remove the analoge thermistor and slide a DS18b20 temperature sensor down the thermostat. While that is a plausible alternative, I didn't want to mess around with the testing of such a thing. If your geyser is more accessible (and less essential) than mine, try it, by all means! 🙂

For more details on exactly what is entailed, please see this MyBroadband post: https://mybroadband.co.za/forum/threads/esphome-geyserwise-smart-thermostat.1231463/

Edited July 19, 20231 yr by RoganDawes