Switchboard WiFi monitoring and control of individual circuits using home assistant

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timmmay

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#318805 23-Feb-2025 11:08

I'd like to be able to turn my hot water cylinder on / off using home assistant, based on available solar capacity once we get a solar system installed. I don't need power metering on that circuit, but I'd quite like to monitor power usage for a few other circuits such as the ducted heat pump and have the data imported into Home Assistant.

Are there any good quality, NZ certified devices I could have my electrician install can install in our modern meter box that will let me monitor and / or control individual circuits? I guess the Shelly Pro1 relay can control, and the Pro1PM can monitor and switch? Are these good options for Home Assistant integration, or is there something better? How's the reliability? Having the relay fail and not having hot water for a week until we can get an electrician out would be extremely unpopular with my family.

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#3345983 23-Feb-2025 15:47

I used a Finder relay (NZ certified) to do the switching (specifically a Finder 22.23.9.012.4000, 12VDC coil) and then you can control that from anything you like, in my case modbus since the distribution board is already set up for that.

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#3346004 23-Feb-2025 16:50

neb:

I used a Finder relay (NZ certified) to do the switching (specifically a Finder 22.23.9.012.4000, 12VDC coil) and then you can control that from anything you like, in my case modbus since the distribution board is already set up for that.

Thanks Neb. The finder website is giving me errors, so ironically I can't find the product on the finder website. Is the Finder relay good for simple switching and also for power monitoring?

I never heard of modbus. What does it mean that the distribution board is already set up for modbus? Does it integrate into HA easily? I could type it into Google or an AI but sometimes humans are better at explaining things...

Do you / anyone know if the Shelly products are certified for NZ? I'm not using anything at the switchboard that's not certified for NZ.

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#3346009 23-Feb-2025 17:13

For hot water, buy a Paladin from @Terciops and don't look back. Nothing you cobble together with contactors and HA will ever come close to the efficiency that the Paladin achieves. We haven't paid for hot water since installing it. Note it doesn't natively interact with HA, but that can easily be overcome by purchasing the remote monitor to go with it, then attaching an ESP32 to it. Be happy to show you what I've done if you go down that route.

For switching / monitoring other circuits, I use Shelly devices. An EM3Pro does nearly all the monitoring I need, and I use PM1s for individual devices.

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#3346017 23-Feb-2025 17:28

Modbus is the most widely used communications protocol for automation and energy monitoring. It's ancient (first published in 1979) so it lacks a lot of modern functionality and it's notoriously a PITA to commission if the manufacturers documentation is poor but it's also incredibly robust and will run on almost anything for small networks.

There's a few different flavours with Modbus RTU (RS-485) and Modbus TCP/IP being the most common.

HA does have Modbus integration but there's a bigger learning curve compared to something more modern. If it's TCP it's not too hard, if it's RTU get ready for a world of pain initially.

timmmay

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#3346020 23-Feb-2025 17:40

Ge0rge:

For hot water, buy a Paladin from @Terciops and don't look back. Nothing you cobble together with contactors and HA will ever come close to the efficiency that the Paladin achieves. We haven't paid for hot water since installing it. Note it doesn't natively interact with HA, but that can easily be overcome by purchasing the remote monitor to go with it, then attaching an ESP32 to it. Be happy to show you what I've done if you go down that route.

For switching / monitoring other circuits, I use Shelly devices. An EM3Pro does nearly all the monitoring I need, and I use PM1s for individual devices.

Our installer is saying he hasn't used diverters in a while, he had quite a few failures and stopped using them about five years ago he said. He's suggested a solar catch relay, which is basically an on / off system to heat the hot water or not, as opposed to feeding it only the power you want it to have, and costs $600 fitted. He's also said the timer we have already is good enough to start with given it's there already. I figured I could do the same as a solar catch relay for cheaper with a Shelly or similar.

Having a proper diverter would be better, but the another installed quoted $1800 for an Eddi. I don't think there's enough ROI to spend that much money on one. Even if the Palidin was $1000 fitted would take a long time to pay for itself compared with an $80 timer that I automate myself. I'd rather not having to muck around myself though.

The Palidin isn't explained well on their website either. For example, how does it know the temperatures in the cylinder? Are there sensors or something? Where would they go and how are they fitted?

timmmay

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#3346021 23-Feb-2025 17:40

Handle9:

Modbus is the most widely used communications protocol for automation and energy monitoring. It's ancient (first published in 1979) so it lacks a lot of modern functionality and it's notoriously a PITA to commission if the manufacturers documentation is poor but it's also incredibly robust and will run on almost anything for small networks.

There's a few different flavours with Modbus RTU (RS-485) and Modbus TCP/IP being the most common.

HA does have Modbus integration but there's a bigger learning curve compared to something more modern. If it's TCP it's not too hard, if it's RTU get ready for a world of pain initially.

That sounds like a real PITA. I wonder if the Shelly with direct integration would be better - if it's permitted for NZ.

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#3346023 23-Feb-2025 17:45

timmmay:

Handle9:

Modbus is the most widely used communications protocol for automation and energy monitoring. It's ancient (first published in 1979) so it lacks a lot of modern functionality and it's notoriously a PITA to commission if the manufacturers documentation is poor but it's also incredibly robust and will run on almost anything for small networks.

There's a few different flavours with Modbus RTU (RS-485) and Modbus TCP/IP being the most common.

HA does have Modbus integration but there's a bigger learning curve compared to something more modern. If it's TCP it's not too hard, if it's RTU get ready for a world of pain initially.

That sounds like a real PITA. I wonder if the Shelly with direct integration would be better - if it's permitted for NZ.

Modbus devices are typically built better than consumer home automation gear. They are normally build for industrial and commercial applications.

It can be worth the extra FAF for gear that will last 20 years but it's really a judgement call.

neb

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#3346025 23-Feb-2025 17:47

The Finder is just a relay, it's a case of tracking down one that's sold here (so with SDoC) that fits the bill. In my case I needed a 12V coil with at least one pair of NC contacts, which that one does (it fails closed so there's always hot water). The relay is the bit that's dealing the with mains power so that's the bit that needs to be certified.

Modbus is a signalling protocol used for industrial control, I've got power meters in the distribution board that report via modbus so adding the modbus relay control was a no-brainer. It's not a just-works thing like the Shelly, you need a modbus TCP gateway to talk to the modbus-serial devices and then a modbus -> MQTT translator. You can get the former from your favourite crapvendor, and for the latter I use MQMGateway, an open-source gateway. Once it's in MQTT it's directly accessible via HA.

So the chain is power meters / relay -> modbus serial -> modbus TCP -> MQMGateway -> MQTT -> HA. It looks complex but it's just a case of plugging one thing into the next as you go from serial -> TCP -> MQTT. The reason why modbus is primarily serial is because it has a high level of noise and interference immunity, so you can run it over rubbish connections and long distances without problems.

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#3346026 23-Feb-2025 17:49

Handle9: If it's TCP it's not too hard, if it's RTU get ready for a world of pain initially.

RTU isn't a problem, you just gateway it to TCP. Waveshare have good-quality products that do this for you. The only hassle is you need to set the modbus address and baud rate on the device before you hook it up.

Having said that, if you just want something that works then modbus probably isn't for you. I use it because, well, I work with it anyway, and because as the name says it's a bus, you can hook any number of things to it. I've got maybe 30 devices connected up on it.

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#3346027 23-Feb-2025 17:54

neb:

Handle9: If it's TCP it's not too hard, if it's RTU get ready for a world of pain initially.

RTU isn't a problem, you just gateway it to TCP. Waveshare have good-quality products that do this for you. The only hassle is you need to set the modbus address and baud rate on the device before you hook it up.

It depends on the quality of the documentation. The amount of time we've wasted on poorly documented RTU devices over the years is incredible. A heap of them have weird stop bit or parity implementations. It's not so bad with one device.

Then there's weird register implementations with reversed doubles that aren't in the docs....

timmmay

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#3346031 23-Feb-2025 18:06

Thanks for the detailed explanation neb. I really don't want to add something fiddly, even if once configured it works fine for years, when there are more modern options. The Shelly Pro 1 appears to have an SDOC so it should be legal, but I need to validate.

I'm open to a diverter, but at $1800 for the EDDI (from one expensive vendor) that's pretty steep - the payback period would be really long. I saw another price for $1300 fitted. I like that they can send any amount of power to the hot water cylinder, not just on / off. The Paladin looks like a solar catch relay rather than a diverter as it has a relay rather than variable output. It looks like it can only turn the hot water system element on or off if there's enough power available to run the 3kw rather than just sending 1kw if that's what's spare like a diverter would.

Home Assistant should be able to see total generation, current power usage, current exported power, and make a reasonably good decision about whether to turn the hot water cylinder on or off. That's not useful if we sell that house, but that's also not really our problem.

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#3346033 23-Feb-2025 18:16

timmmay:

Ge0rge:

For hot water, buy a Paladin from @Terciops and don't look back. Nothing you cobble together with contactors and HA will ever come close to the efficiency that the Paladin achieves. We haven't paid for hot water since installing it. Note it doesn't natively interact with HA, but that can easily be overcome by purchasing the remote monitor to go with it, then attaching an ESP32 to it. Be happy to show you what I've done if you go down that route.

For switching / monitoring other circuits, I use Shelly devices. An EM3Pro does nearly all the monitoring I need, and I use PM1s for individual devices.

Our installer is saying he hasn't used diverters in a while, he had quite a few failures and stopped using them about five years ago he said. He's suggested a solar catch relay, which is basically an on / off system to heat the hot water or not, as opposed to feeding it only the power you want it to have, and costs $600 fitted. He's also said the timer we have already is good enough to start with given it's there already. I figured I could do the same as a solar catch relay for cheaper with a Shelly or similar.

Having a proper diverter would be better, but the another installed quoted $1800 for an Eddi. I don't think there's enough ROI to spend that much money on one. Even if the Palidin was $1000 fitted would take a long time to pay for itself compared with an $80 timer that I automate myself. I'd rather not having to muck around myself though.

The Palidin isn't explained well on their website either. For example, how does it know the temperatures in the cylinder? Are there sensors or something? Where would they go and how are they fitted?

I can see your point about the cost of a diverter vs a switch, however I'd argue that the ROI would likely be better with a diverter.

With a diverter, the instant you are making enough solar to begin exporting, it is used to heat the HWC. Starts at 1W and works its way up from there each morning. Some days here in winter, we might only make an excess of around 800W, and that all goes in the HWC and slowly brings the temp up.

If you use a switch, you've got the option of on or off. If you wait until a certain amount of export before turning the HWC on, everything before that is wasted to the grid for chump-change - and if you don't make your export limit, then no hot water heating that day. Or you use grid to do it later, and dollars to doughnuts it will cost you more than the pittance you were paid for export. If you make that export limit quite low, then sure you will offset the cost of heating the water, but you'll still be paying to import anything over what your solar system is making.

Paladin likes to know the water temp for a few reasons - one, so it can know when to stop heating the cylinder each day; two, so it can keep an eye on Legionella for you - if you've had a very poor solar week for instances and the cylinder hasn't gone over 55°, Paladin will take it up to that temp for you overnight (when the power tarrif is likely to be lowest) so bugs can't breed; three, so that if you use a heap of hot water at any particular time, Paladin will hold the HWC at a minimum temp that you set (40° or 50° from memory) using as little grid as possible so you don't have cold showers, until either you're exporting enough solar to heat the HWC, or the health top up timer expires and it will again heat it for you.

The temp sensor goes against the cylinder wall, under the insulation. You essentially pop to the thermostat cover, slide the sensor in, wind the mechanical thermostat up to its absolute max, and Paladin takes care of the rest. If your mains is close to your cylinder, then the sensor plugs directly into the Paladin, and a CT clamp goes around your mains. If, like me, your cylinder is in another building from your mains, then there is a remote temp sensor that uses LoRa to communicate with the Paladin. It will also operate without the temp sensor, but you then lose the top up and health top-up functions - Paladin will just become a dumb diverter.

From an ROI perspective, think of your HWC as a battery - you're storing you energy in there to use later. You're not paying anything for the energy that's stored in there, vs exporting for peanuts and buying back later for much more. A switch will work, but will never be as efficient.

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#3346034 23-Feb-2025 18:22

timmmay:

Thanks for the detailed explanation neb. I really don't want to add something fiddly, even if once configured it works fine for years, when there are more modern options. The Shelly Pro 1 appears to have an SDOC so it should be legal, but I need to validate.

I'm open to a diverter, but at $1800 for the EDDI (from one expensive vendor) that's pretty steep - the payback period would be really long. I saw another price for $1300 fitted. I like that they can send any amount of power to the hot water cylinder, not just on / off. The Paladin looks like a solar catch relay rather than a diverter as it has a relay rather than variable output. It looks like it can only turn the hot water system element on or off if there's enough power available to run the 3kw rather than just sending 1kw if that's what's spare like a diverter would.

Home Assistant should be able to see total generation, current power usage, current exported power, and make a reasonably good decision about whether to turn the hot water cylinder on or off. That's not useful if we sell that house, but that's also not really our problem.

Paladin is 100% a diverter - the relay you mention is an SSR that can turn on and off up to 50 times a second to keep you export/import at zero while your HWC heats up.

neb

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#3346043 23-Feb-2025 18:38

Handle9: It depends on the quality of the documentation. The amount of time we've wasted on poorly documented RTU devices over the years is incredible. A heap of them have weird stop bit or parity implementations. It's not so bad with one device.

Then there's weird register implementations with reversed doubles that aren't in the docs....

Never run into bits-on-the-wire problems, but then the TCP gateways possibly have a bit of intelligence in them to transparently work around problems. The main issues I've run into are modbus emulators that respond correctly to the three specific messages (byte sequences) the vendor tested them with and nothing else, at least give garbage results for other modbus requests.

timmmay

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#3346050 23-Feb-2025 19:00

Yeah a diverter is absolutely better than a switch, that's what I was trying to say above. I assumed a diverter would send lower currents to the hot water cylinder rather than doing odd time slicing. I guess sending 3kw (our element size) for say 16/50ths of a second has the same effect on paper as sending 1kw for the whole second, but does it really work like that? You're still sending 3kw, then nothing, then 3kw, then nothing. The EDDI works in a way that seems more sensible to me - not being an electrical engineer.

Here's a Perplexity AI generated summary of the differences between the Eddi and the Paladin: "The eddi solar diverter and the Paladin diverter operate differently to maximize solar energy use for water heating. The eddi uses variable power control with proprietary VariSineTM technology to smoothly adjust output voltage and current, allowing it to divert excess power in real-time to heating loads as small as 100W up to 3.68kW1. In contrast, the Paladin employs a cyclical on-off approach, using a metaphorical "water tank" system. It monitors solar input and household power use, waiting until excess solar power reaches a certain level before diverting power to the hot water cylinder element. The Paladin also incorporates a DELTA_T function to anticipate and respond to potential temperature drops, while the eddi doesn't mention a similar predictive temperature management system".

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