I am embarking on my solar journey, and plan to have a completed solar+inverter+battery system up and running before the end of next month. 

My plan is to connect my geyser to the AUX port on the Sunsynk inverter, such that I can power the geyser only when there is sun, and the batteries are charged. I want to integrate a Geyserwise with this setup, so that I can have a little more control over the geyser temperature, and so that I can see what the temperature is at the end of the day, allowing me to better understand if I need to add more solar capacity or not. 

Since the geyser will be essentially controlled by the inverter, I run the risk of not having hot water if it's inclement weather, and I'm running off the batteries during the day. So ideally I would like to have a backup grid connection that can then be controlled by the Geyserwise. 

Summary of what I need/want and what I'm thinking:

• Set the temperature on the geyser thermostat to max. If there is surplus PV, then I push the geyser as far as I can go (70C on the thermostat)
• Set the temperature on the Geyserwise to a safe minimum, say 40C. So that if the temperature drops below this, the grid kicks in to boost the temperature. 
• Some way to connect the Geyserwise element relay directly to my grid source, but still keep the keypad powered by the inverter, so that I always have my temperature display, even when there is loadshedding or when the Inverter AUX port is off. I want to get the connected version of the Geyserwise, as I'm interested in plotting geyser temperature over time so that I can better understand usage patterns and whatnot.

Initially I thought I can just connect the element both to the inverter AND the Geyserwise, and thus power the geyser from one or the other. But I don't think this is safe, as I run the risk of the inverter providing power, while the Geyserwise relay is closed, resulting in the inverter essentially backfeeding into the grid via the Geyserwise. 

So my question to the forum is what do? Is there a way to set up the geyserwise to control 2 AC sources for temperature control? Presumably it can do it with AC and a pump, but since my 2nd power source is not a solar collector but PV-AC from the inverter, I'm not sure what to do. 

Connecting the Geyserwise directly to the inverter AUX output is useless, as then I don't have grid backup, and the thing will be powered off most of the time.

I'm finding the Geyserwise manuals to be of poor quality, so I can't really figure out if I can do with it what I want to do by reading it. 

Do you already have the Geyserwise? They released an IoT version of the controller that you could then (through some logic) do the things you want done. 

No I don't. I was considering buying the TSE model from Sustainable this week, but then saw that Livestainable has a Tuya version for sale. I have an unnecessarily complex homeassistant setup already going, so I am more than comfortable doing whatever integrations I need to do from the Geyserwise into HA for reporting and control purposes.

My bigger question really is if the GW can select which AC source to use, either grid or inverter. I'm not sure if I can do what I want to do electrically, without introducing additional relays and/or switches. 

I mailed GW support with my query as well, and will report back if they come back to me. Interested to know if forum members have done something like this already. 

1 hour ago, suds7162 said:

No I don't. I was considering buying the TSE model from Sustainable this week, but then saw that Livestainable has a Tuya version for sale. I have an unnecessarily complex homeassistant setup already going, so I am more than comfortable doing whatever integrations I need to do from the Geyserwise into HA for reporting and control purposes.

My bigger question really is if the GW can select which AC source to use, either grid or inverter. I'm not sure if I can do what I want to do electrically, without introducing additional relays and/or switches. 

I mailed GW support with my query as well, and will report back if they come back to me. Interested to know if forum members have done something like this already. 

So what you want / need is an automated changeover switch for Grid / Inverter that is connected to the geyser(wise) the Tuya GW will help with when to switch on and off based on load + PV at least. Im not sure about the changeover. Although... if its on AUX then by default its either powered by the SUN based on AUX-on conditions and the grid based on AUX-off conditions

Edit: at least that's how I understand it (aux) to function

Edited March 24, 20232 yr by mzezman

Thanks, I was thinking the same thing as I was typing out my previous message.

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Although... if its on AUX then by default its either powered by the SUN based on AUX-on conditions and the grid based on AUX-off conditions

I'm not sure I understand you here. Can the Sunsynk output grid on the Aux, if PV is not available? If this is the case, then I am about halfway there I think, as then at least I have Grid available to power my geyser if there is no sun = never a cold geyser. 

What I'm then missing is the ability to set an independent max temperature for each power source: 30C for grid, 75C for PV. I want to minimize my grid usage as much as possible, and setting the grid-powered temparature to such a low value means I will only really pull grid in a real emergency such as inclement weather for multiple days, which almost never happens.

In the end it might be less of a headache to roll my own solution, with an ATS like you suggest. Temperature sensor stuffed up the thermostat tube, a microcontroller with some configuration, and then a 20A ATS that can be controlled by an external signal from the micro.

5 minutes ago, suds7162 said:

Thanks, I was thinking the same thing as I was typing out my previous message.

I'm not sure I understand you here. Can the Sunsynk output grid on the Aux, if PV is not available? If this is the case, then I am about halfway there I think, as then at least I have Grid available to power my geyser if there is no sun = never a cold geyser. 

What I'm then missing is the ability to set an independent max temperature for each power source: 30C for grid, 75C for PV. I want to minimize my grid usage as much as possible, and setting the grid-powered temparature to such a low value means I will only really pull grid in a real emergency such as inclement weather for multiple days, which almost never happens.

In the end it might be less of a headache to roll my own solution, with an ATS like you suggest. Temperature sensor stuffed up the thermostat tube, a microcontroller with some configuration, and then a 20A ATS that can be controlled by an external signal from the micro.

I THINK so... but I could very well be wrong though - @Scorp007 @Leshen maybe you can chime in here on AUX?

Reading through the Sunsynk manual, there is a setting called "on grid always on" which I think means switch Aux always on when there is grid available. Which is NOT what I want, UNLESS the geyser temperature is below 30C or whatever.

Maybe the ATS is not needed, if I can somehow remotely control that setting with a microcontroller. Read the geyser temperature, and if below minimun, change the inverter settings to switch on the aux if the grid is on.

Edited March 24, 20232 yr by suds7162

Or I can just be lazy, and keep that setting off always, and when we feel the water in the showers getting a little chilly, then we manually turn it on. Like I said, I hope/expect this to almost never happen. I'm in Pretoria, almost no extended inclement weather, so maybe I'm overengineering something here.

I still would like to know if I can do what I want to do with the GW, because then I might still install it, even if it's only so that I can measure and plot temperature and all that.

Subscribed. I'm also looking to manage my geyserwise system a bit better. 

I have a Victron setup that talks to my HA via MQTT. Grid state, Batt SOC and more is already being pulled in by HA and used as conditions. My entire house is on the essential side and like you I don't want the geysers to drain the batteries.

I would also like to manage geyser temp and load (power pulled by the geyser) intelligently. A easy way woud be to simply switch the geyser on and off via a sonoff pow or similar. But then I lose the circulation pump during those times. I would also like to bump up the geyser temp and use it for additional energy storage when the batteries are full.

I'm a DevOps/Systems engineer by day. So I don't want any cloud based control I don't have oversight over. So all my Sonoff bits have been reflashed with tasmota. Can the same be done with the Geyserwise Tuya?

Cool there are at least two of us that want the same thing 😂

Surely there must be more folks who are looking for this? I have to admit, some of the people that I have spoken to with solar already installed don't even know they need to optimize their systems in this way at all. Folks with dozens of KWp on the roof, multiple lithium batteries and all that, and then they still fail to get off the grid fully, and only reduce their bill by 50%. And that's with a consumption level that's "normal" for their household. 

Solar panels that don't work 100% capacity, 100% of the time (when the sun is available) is almost criminal in my mind, because you paid all that money for the damn things, only to sit on your roof and do nothing!

/rant over

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Can the same be done with the Geyserwise Tuya

Not sure. Their own website is woefully lacking, and does not say anything about this product even!

I found this github repo, which appears to be custom firmware for the MAX. The circuit board photo shows what looks like an ESP-something on the inside of the display PCB. So presumably you can flash tasmota or similar to it no problem.

I would also prefer local only for things like this. Can't have the geyser go cold because the internet or servers went down, that's a big no-no!

54 minutes ago, suds7162 said:

Or I can just be lazy, and keep that setting off always, and when we feel the water in the showers getting a little chilly, then we manually turn it on. Like I said, I hope/expect this to almost never happen. I'm in Pretoria, almost no extended inclement weather, so maybe I'm overengineering something here.

I still would like to know if I can do what I want to do with the GW, because then I might still install it, even if it's only so that I can measure and plot temperature and all that.

I have a geyserwise system here in kzn.My geyser element was reduced to a 2kw from 4kw.I have nothing on non essential and in holiday mode the water gets more than hot enough without using the heating element BUT when we had tons of rain and cooler days I just pressed the red button on control panel to manually use the geyser element.Plan your times around peak solar output.

1 hour ago, root said:

Subscribed. I'm also looking to manage my geyserwise system a bit better. 

I have a Victron setup that talks to my HA via MQTT. Grid state, Batt SOC and more is already being pulled in by HA and used as conditions. My entire house is on the essential side and like you I don't want the geysers to drain the batteries.

I would also like to manage geyser temp and load (power pulled by the geyser) intelligently. A easy way woud be to simply switch the geyser on and off via a sonoff pow or similar. But then I lose the circulation pump during those times. I would also like to bump up the geyser temp and use it for additional energy storage when the batteries are full.

I'm a DevOps/Systems engineer by day. So I don't want any cloud based control I don't have oversight over. So all my Sonoff bits have been reflashed with tasmota. Can the same be done with the Geyserwise Tuya?

I'm not sure TBH - there IS the LocalTuya integration available in HA but it requires a cloud connection in the setup - i'm also not sure if it works with the GW specifically

50 minutes ago, Nicholas Strachan said:

Plan your times around peak solar output.

That bit is done with scheduling. I want more though. I have a system (HA) in place to intelligently with rules and conditions optimise my usage. Like @suds7162 correctly pointed out, you can have a billion watt of panels on the roof and still end up relying on the grid on a rainy day.

My pool pump is automated to only run when the batteries are above 98% SOC and turn off as soon as its not. 

I want the same for the geyser but with additional conditions and without the cloud.

@mzezman LocalTuya is a cloud interface that emulates local control.

@suds7162 I think I'll have to buy a replacement geyserwise max tuya controller and experiment reflashing it.

If not I'll also have to build a custom unit... I do have all the components for it. But time to build and debug a critical household system is the problem. The missus does not like a cold shower.

1 hour ago, Nicholas Strachan said:

I have a geyserwise system here in kzn.My geyser element was reduced to a 2kw from 4kw.I have nothing on non essential and in holiday mode the water gets more than hot enough without using the heating element BUT when we had tons of rain and cooler days I just pressed the red button on control panel to manually use the geyser element.Plan your times around peak solar output.

@Nicholas Strachan I don't understand. Do you have a thermal system, with a collector on your roof that is providing the primary source of heat, and then when needed you go over to AC by overriding on the keypad?

@suds7162  On a Geyserwise panel, in a programmed off-period, the geyser can be manually turned on by simply pressing button 1 & 4 simultaneously.  In this mode it will still stay in limit of the programmed (set) temperature.  At any stage you can press those two buttons again to default back to normal, timer-controlled operation.

17 hours ago, suds7162 said:

@Nicholas Strachan I don't understand. Do you have a thermal system, with a collector on your roof that is providing the primary source of heat, and then when needed you go over to AC by overriding on the keypad?

Yes,that is correct.Its not your normal vacuum tube system.On a half decent day the water without any geyser element input gets to 60 deg.If its a shitty ,rainy cool day then i just press 1 button on the pad and it switches on the normal heating element in the geyser.I dont have an essential split so the power for the geyser element comes from solar if there is enough pv output OR from eskom.My sunsynk takes care of all of that.

14 hours ago, Modina said:

@suds7162  On a Geyserwise panel, in a programmed off-period, the geyser can be manually turned on by simply pressing button 1 & 4 simultaneously.  In this mode it will still stay in limit of the programmed (set) temperature.  At any stage you can press those two buttons again to default back to normal, timer-controlled operation.

When you press 1 and 4 together it takes it out of holiday mode and back to on and the set timer times will work.Press 1 and 4 again and the screen goes mostly blank and that is holiday mode.The water still gets hot BUT the heating element and timer dont come on.To manually switch on the heating element you do 1 and 4 to light up the screen THEN press 1 and you get 3 red raindrops which means the geyser element is on and heating.

 In Holiday mode

By pressing the red button you manually switch on the element,see the 3 red raindrops

 

By pressing those 2 buttons together you bring the system out of holiday mode and as per previous pic,then press the red button to switch on heating element.I do have a timer set between 1 and 3 pm to heat geyser but for now i dont need it.

Thanks @Nicholas Strachan  I have moved and haven't been using a Geyserwise for over three years now.  My memory is a bit rusty.

I wish the Geyserwise would have a display dimming function.  The display was way too bright for me.  A redesign and a flush mounted control panel option would be good.

@Modina and @Nicholas Strachan thanks for your responses. But I don't think you understood my question and the purpose of this thread. Maybe I did not express myself clearly enough.

I have a regular electrical geyser. No solar, no collector, nothing.

I am planning and speccing out a sunsynk-based solar and battery backup system so that I can get off the grid and get away from loadshedding. The Sunsynk inverter has a capability where it can feed excess solar generated electricity into a dedicated load, via a specific output on the inverter, called the AUX port. I want to connect my geyser to this port, and then use excess generated solar elecctricity to heat up my geyser once my batteries are charged. 

In summary, what I want is to be able to heat my geyser with 2 different electrical AC sources, one from Eskom, and one from my inverter. I want to set up rules in the control system such that when the temperature dips below 30-40C, then I activate the Eskom source to heat the geyser back up. When the temperature is between 30-65C, then I use the inverter's excess solar output to heat it. 

I am not interested in installing a thermal collector system or anything. I want to keep my geyser as it is. 

Based on the conversations I've had here, and an email from Geyserwise directly, it does not seem like it's possible to do what I want to do.

@suds7162  I understood your question perfectly well; just ended up down a rabbit hole about the manual override button.

I just opened the Geyserwise MAX control box to have a look.  They switch L & N with two separate SPST relays.  They use Hangfa HF2160-1A-12D relays.  I guess one could replace these relays with SPDT version and then wire these extra contacts out via the white chocolate block (see picture below) that is currently used for solenoid and pump wiring.  The GW would temperature control up to 40degC and then release the two relays.  Once released, you could feed your AUX output to the NC contacts.

However, having an open ended SunSynk 230VAC supply could result in overheating, boiling, safety-valves opening or explosion.  Geyserwise does supply and recommends you wiring a safety over-temperature switch (in series with the element) to prevent the above.  But this mechanism is NOT a control mechanism, but rather a if-all-else-fails safety cut-out which needs to be reset manually by pushing a mechanical button.  You would need to implement a temperature-set-point power cutoff.  That is not so easy.  Just getting another temperature sensor thermally connected to the geyser would be a challenge and it would be a lot of work to back-engineer and tap-off the GW sensor.

I agree that the GW documentation is useless.  There isn't ANY info on their website on the MAX, except some spec sheet.  I don't know the operation of the pump and solenoid.  I would like to see at least a block diagram.  However, I have just found this document online: https://cat.co.ke/wp-content/uploads/2016/02/Geyserwise_MAX_Manual.pdf

You also wanted the Geyserwise powered under all conditions.  Well you could power a 2nd small transformer from the Inverter's output, feed the secondary through another bridge rectifier and then summate the output of the two rectifiers.  Possible, but not exactly neat.  However, rolling your own design is also not likely to be very neat, except if you have many, many hours to burn on this project.

Please note that the GW TSE version uses a much smaller control-box.  I can't remember if they used a double pole relay there to control the element.  I doubt it.  The TSE only has the microcontroller at the display panel.  The control box has a final transistor to switch the relay.  The MAX has a 2nd micro on the PCB in the control box, it sits on the solder side underneath that small xtal (see pic).   I don't have a TSE at the moment, but might still have some pictures of it.  I once had to replace the power transformer on my TSE.  Those LEDs are driven very hard, with a too bright display for my liking.  Obviously the transformer also doesn't enjoy the loading of the bright LEDs...

If you decide to go with a GW, I suggest buying the MAX.  Firstly because we now know that it switches L&N and secondly, the MAX has a much bigger control box with more room to modify things.  The Hangfa HF2160 family certainly has SPDT relays that are a drop in replacement.  The heavy duty contacts are spade terminals.  So this modification could be done very neatly.

@Modina your last post made me think a bit about the situation, and I realize the solution was staring me in the face the whole time: 

 

Basically what needs to be done is a DPDT contactor, that has Eskom and the inverter AUX port as the two inputs, and then the Geyserwise's element output (L2 & N2) is connected to the contactor's control inputs. The inverter output is connected to the NC side of the contactor, so it feeds the geyser by default, and when there is no power on AUX (due to no sun), and the temperature dips below my minimum threshold (40C), then the geyserwise kicks in, switches on the contactor, and the geyser is fed Eskom power. If there is loadshedding then I'm screwed, but there's no way around that.

The Geyserwise itself is then powered as an essential load, from the inverter's main output. So in theory it'll always have power. 

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However, having an open ended SunSynk 230VAC supply could result in overheating, boiling, safety-valves opening or explosion.

I was under the impression that the geyser still has it's original thermostat installed, with the Geyserwise probe inserted first in the pocket, and then the thermostat stem following after? Looking at the pictures now it seems like Geyserwise has their own modified thermostat that you insert into the geyser. It looks like it comes with a thermal cut-out at least. I'm a bit disappointed that I then can't use the original thermostat, as my plan was then to use that to define the max temperature of the geyser (70C). Thermal collector geysers popping their tops due to over temperature is a regular occurence in South Africa, so it's actually nothing new, and might even be a good feature because you get to test the over-pressure valve on a regular basis 😂. My parents have a thermal system installed. After one day of no use the geyser is at 60C. After 2 days of no use the geyser is at 90C, on the third day the over pressure pops, and spews boiling water all over the roof and garden. When they go on holiday, they need to get someone to cone in every day to draw a hot bath, and drain it again, to bring the geyser temperature down to something safer. 

I am loathe to modify the Geyserwise unit itself as you originally suggested, so I think my plan safely sidesteps that issue!

First I wanted to draw a similar diagram using an external DPDT relay, but when I opened my MAX controller I thought modification will be easier than sitting with extra boxes, heavy duty jumper cables, etc..  One could simply disconnect the primary of the small transformer and establish a new connection to your Essential DB.  That way, the GW will always be on.   If you can get the SPDT drop-in replacement relays it would make a very neat mod.  You would simply de-solder the SPST and replace with the SPDT.  No PCB modification would need to be done.  The high currents are all terminated from the top of the relays using spade connectors.

With GW you normally remove the thermostat and replace it with a new brass tube that contains the thermistor.  I will include a picture showing a tube with the thermal cut-out but the pic is not very clear, sorry.  You also get tubes without the thermal cutout.  Because brass is a good heat conductor, one could mount a LM35 analog temperature sensor, or any of the I2C or SPI interfaced digital temp sensor ICs at the neck of the tube.  Squeezing a second sensor down that tube might also be possible.

Not sure if you are in Gauteng.  If you are, I would recommend go and see GW in Centurion.  The guys are very helpful and they have all sorts of brackets and extra sensors and other items that might be useful for a customized project.  There they can show you all the different GW models, how the bare PCBs look and one can then make a better decision as to what is and is not possible.  GW repairs are done on a PCB replacement basis, so you might even be able to get an old PCB who's relay contacts have burned for cheap, and then replace the relays with double-throw contacts.

GW also has a centre in Cape Town, but I haven't been there yet.  I am not sure where they have their main branch.
 

Thanks for the picture of the thermostat. That's helpful and explains a lot.

I don't want to modify the GW directly firstly because of warranty concerns, and it's one of those things where one day when I'm not there, I want an electrician/plumber to be able to easily understand what is going on. Most of them should at least understand what a Geyserwise is, and how to operate it. Modifications on the PCB breaks that knowledge to a degree. The idea is that a contactor in the DB board, clearly labelled and all that will hopefully make things easier to follow and understand.

But a direct replacement of those relays will do the same thing ultimately, and might be the easiest to implement, because it requires minimal mods on the DB itself.

In a perfect world, I want to be able to use the geyser's original thermostat. Those devices are reliable, and they fail open, not closed. This seems like it's the one missing piece to the puzzle. I'm not comfortable wiring in another temperature sensor and using software to control things. My software is always written 100% fault free, but still. Again, a plumber should be able to come and change the geyser temperature if I'm not there, and you do that by turning the little dial on the geyser thermostat. So maybe I need to figure out if I can somehow get the GW temperature sensor mounted on to an existing thermostat, and not use the GW thermal cut-off at all. 
 

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Not sure if you are in Gauteng.  If you are, I would recommend go and see GW in Centurion. 

I might just do that. Maybe they are interested in integrating this idea into their existing product. Adding DPDT relays and adding a "second AC source" to their existing line is a cheap but very powerful enhancement imo.

 

Alternatively, if the thermostat mod route does not work, then I can install one of the GW PTC elements. That is basically an element and thermal-cutout-in-one. Super safe, fails open, and then you know you are not boiling your geyser on sunny days.  The PTC element is just mad expensive. It's not really that expensive! Geyserwise PTC Stainless Steel 230V Electrical Geyser Element 2kw | LiveStainable

Edited March 27, 20232 yr by suds7162