Believe me I didn’t start with a Geyserwise Dual. 
I thought that I could install 4kW of solar PV and run my house during the day with a 3kW geyser element. (Bear with me: I’ve simplified the scenario to make my point)
If the geyser could be switched on as soon as the necessary available PV power was available then I wouldn’t need to schedule when it was switched on (or reduce the element to 1kW)
I’m convinced this is possible but I’ve yet to see it being implemented.
As @plonkster pointed out, 1kw, there are factors to consider, philosophical (my words), vehicle (again, my word), and engineering and scientific facts.
Where you are, most of us have been, over the last decade.
The core group here, we’ve been around on forums for a while, thrashing and learning stuff, the hard way.
You are starting where we were.
Drop me a PM, we can then talk on the phone. Then, when it makes sense, you can “pass it on” here on this thread.
EDIT:
Food for thought … on another forum, you can either afford a 4x4 or a proper grid-tied system. Few can afford both, and if they can, they pay someone to do the solar side. My point, some ideas shared on some forums are not based on real-life hard-core experiences, walking the talk, as most here have done.
No disrespect, just what I’ve seen the last few years.
Money buys the whiskey, we bought that, and we walk with Johhny … all the way.
Sonof, Shelly, personal preferences.
Really saving on heating a geyser, now THAT is a challenge,
It helps a lot IF you’ve got full access to live data of your solar system and house loads … whilst keeping the 'langhaar huisdiere" happy … most of the time.
In general, I find that spending money to add more panels is a more efficient use of my funds, than spending comparable amounts of money trying to squeeze every last electron out of an array that is too small.
These fancy mods add up pretty quick to several grand.
Several grand can get you more panels.
Then you’ll have watts for 25 years. Which I’ll wager is about 15-20 years longer than some reflashed device or a fad geyser element or whatever is the latest gadget.
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This is easily done with Home Assistant
I’ve been toiling and troubling now for weeks, the thousands you speak of … it adds up very fast, and then the CoC comes on top of that.
Got this gorgeous blond “langhaar huisdier” staying with me willingly, she even listens to most of my ideas. She asked me the other day: “So, these monies you are spending on automation, how much more will it save?”
Bar the 1 x GW Wifi display unit, it became a NEED between 4.1 people, I had to be honest to myself and call it a HOBBY. Nowhere near a NEED nor a WANT.
However, I also realised, as a WANT, when installing brand new or as a full new replacement of i.e. a geyser bursting, some things I could do slightly differently for a couple of ronts extra at the time of new/replacement, not the thousands replacing working CoC’ed stuff.
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Hehehe, I’ve had this discussion in my house too. That being said, I haven’t really added significant more automations in the last 2 years and she enjoys the EskomSePush API integration and the fact that she can turn off the whole house’s lights from bed 
AS long as everything works of course…
@Gman Do you know where I can find these locally?
Unfortunately I think no one in SA will stock them. Best is to import it from Shelly store. It’s going to cost you way cheaper to. I bought it last year when they launch it on the market.
I think the best will be that the guys must club together and import a box full of stuff. Make a order list and everyone pays there amount in before the order “there is a formula that they work all this stuff out”. Then one person do the payment and import. When the stuff lands in SA and DHL sends the invoice for customs, then the rest can be sorted.
Do you mean like this?
The house when we are working:
Then the 2kw geyser is switched on, manually, via the Tuya App GW display.
I want to automate that with NodeRED, the “manual” part, using a Shelly, and a changeover switch to switch the geyser to critical loads when Eskom is LS, but the costs are interesting, and then the CoC on top of that.
Then some clouds come over, and inverter max watts are pulled back to the panel’s max, which is also in NodeRED, so to cater to this scenario, as clouds move over, if in like Cpt, one needs to switch off the geyser again at this time, as LS is a big consideration, supersedes heating the geyser, as batts are damn expensive to charge on Eskom for multiple LS events coming vs heating the geyser once just enough for a shower.
Yes, I think I follow…
What I can’t figure is what the default scenario is? Your Victron system will allocate the PV power to x,y & z as it will when it draws from the resources.
Surely you program the inverter as well as your NodeRED that sits on top?
PS: It was all a lot simpler when they developed the grid-tie inverter: Draw power from PV and if that’s not sufficient draw the balance from the grid… 
Oh sorry! And then when there’s excess power feed it back to the grid…
We don’t feed back to the grid, power can rather go to waste … or switch more things on.
The default scenario:
Draw power from PV and if that’s not sufficient draw the balance from the BATTERIES, then only draw power from the grid.
The software running it all on a Venus, ESS, where the magic happens, the sole goal being to reduce your grid usage unless you override it manually.
Some more detail on how it works, set it up etc:
We then take that further, with NodeRED/Homeassist, hence the Shelly/Sonof of question, to cater further for particular individual needs, hence Victron focussing on Open Source, that one can do that.
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A stupid Shelly question.
If I have let’s say a Shelly Duo bulb and on its light switch I connected a Shelly 1 relay. Can the 2 be linked in the software so that the software handles the 2 devices as a single unit?
In other words if I give a command to switch off the bedroom light, it will know to switch off both the bulb and relay and not only switch off the bulb but the relay stays on.
Also, I read if you have multiple lights in the same room like a bunch of downlighters, you can link them in the software to do the same thing if you for example change colour temperature.
In my case I have 3 ceiling fans on different circuits in my bar area and I also want to put some RGBW LED strips in my bar using the Shelly RGBW2 for control.
So would I be able to link the 3 ceiling fan Duo bulbs and the RGBW2 controller to follow each other if I change colour or something?
I can do this for you. Its just that the Shelly Pro 4PM is very expensive and then as a distributor you need to hold stock in case of swap outs / faulty units. I would be happy to accommodate this if there is enough interest / demand.