Home Assistant Whole House Power Monitoring: NZ Options

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Home Assistant Whole House Power Monitoring: NZ Options

1 | 2 | 3

MarkM536

309 posts

Ultimate Geek

#3101010 7-Jul-2023 16:15

Bewildered:

https://www.se.com/nz/en/product/A9C15030/ict-plus-20a-1p-uc-230vac/

A year ago I had the thought about Modbus energy meters... Such as the iEM2455 - 230V - 100A (https://www.se.com/nz/en/product/A9MEM2455/)

Modbus also gives the option to have multiple of these energy meters on a single communication line (they each have an address).

I've used a cheap DC voltage/current meter which outputs as RS485 'Modbus' into a ESP32 running ESPHome into Home Assistant. It works perfectly fine and modbus is a supported communication within ESPHome.

Not something as easy as a Shelley EM sorry.

michelangelonz

115 posts

Master Geek

#3101082 7-Jul-2023 21:12

Have a Shelly EM works well.

Have a look at this thread.

https://www.geekzone.co.nz/forums.asp?forumId=73&topicId=295843

phrozenpenguin

840 posts

Ultimate Geek

#3120320 25-Aug-2023 21:55

Just updating this with my experiences. I bought a Shelly EM (the 3EM wasn't in stock anywhere, and I didn't need three phase). I got a sparky to install it alongside a contactor and a three way switch.

120A clamp doing energy monitoring for whole house
50A clamp doing energy monitoring only on the HWC
Shelly controlling contactor which can switch on/off the HWC

The three way switch is setup so that regardless of state of Shelly the HWC can still be controlled.

"Auto" - controlled by Shelly
Off - bypassing Shelly
On - bypassing Shelly

Feeding into and controlled by Home Assistant and all seems good so far.

Ge0rge

2052 posts

Uber Geek

Trusted

Lifetime subscriber

#3120321 25-Aug-2023 21:58

What brand / model is the contactor?

phrozenpenguin

840 posts

Ultimate Geek

#3120322 25-Aug-2023 22:05

Ge0rge: What brand / model is the contactor?

Its a 25A Schneider. Sorry not sure the exact model, the only thing visible in the switchboard is "ICT". I left the sparky to source and decide.

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#3120576 26-Aug-2023 13:14

evilengineer:
Solar is on the road map but will probably still be a few years down the track, mostly waiting for house batteries to get cheaper.

How best to monitor that is no doubt a whole separate conversation in itself.

If you're going to go solar at some point, get one of these (that's retail, you can get them a lot cheaper if you've got a contact in the industry), they're MID certified so will handle import and export and report a huge range of parameters beyond just watts-used, voltage, frequency, power factor, import quantity, export quantity, etc.

Bewildered

106 posts

Master Geek

#3120668 26-Aug-2023 20:09

So I looked into a battery and for us it wasn't economically viable....and for a very good reason....we are with Octopus and their rates are super competitive and their solar buy back is a staggering 17c per kWh. Put that against peak, off peak, and night rates of 22c, 16c, and 11c respectively it literally makes no sense to have a battery to store energy for later.

Power I use at:

Night is 11c, I'm better off using as little power as possible during the day and exporting everything at 17c, then load shift into the night and use power at 11c - that's a 6c profit per kWh.
Off peak is 16c, so use/sell it's all the same
Peak is 22c, so the cost difference is just 5c (22c - 17c)....if I dumped power into a battery and used it during peak then the 5c saving that I'd get will never pay for a battery, plus, peak power is running things like an induction hob or oven, plus heating, loads so high that a battery wouldn't like if you want a long battery life.

So a battery is bust. Instead, I put as many panels on the roof as I could fit....better to pay for an extra 10 - 15 panels (an extra $4k-$6k). This is cheaper than a battery and with a minimum of a 25 year productive life those extra panels will last much longer than any battery. This means you produce extra power, which generates credit on your bill....big production in the long months helps offset low production during winter months.

We commissioned in October last year and haven't had a power bill since....at the rate we're going we might yet sneak through with no bill at all....otherwise it is going to be ~$200 max.....which is great for a whole year. And I'm talking total including line charges, not just consumption.

So don't think you need to have a battery to make it work...because that's not the case.

Also create an account at opensolar.com and just have a play to see what your house could produce...if nothing it fun to see what you can fit and also to double check the nonsense the salespeople tell you...Especially double check your power rates - they love assuming power prices are 35c per kWh. Expect a payback period of at least 11 years. :-)

Equinox IT

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.

SpookyAwol

626 posts

Ultimate Geek

#3120775 27-Aug-2023 10:19

Bewildered:

So I looked into a battery and for us it wasn't economically viable....and for a very good reason....we are with Octopus and their rates are super competitive and their solar buy back is a staggering 17c per kWh. Put that against peak, off peak, and night rates of 22c, 16c, and 11c respectively it literally makes no sense to have a battery to store energy for later.

Youre in the South Island? the rates do vary across the country too

Bewildered

106 posts

Master Geek

#3120776 27-Aug-2023 10:27

Nope. In the Wellington region. I've got an uncle in the Manawatu and for him the maths was more or less the same....the power prices are higher but the cost difference between battery / no battery still didn't add up.

I think in most cases only places like Northland where the power price is really high do the economics swing the other way....

On my part I'm waiting for the non-lithium batteries to come....they will be safer, cheaper, and longer lived...and yes, it will be age until they come, but I'm in no hurry. The thought of strapping a lithium bomb to my house, especially if houses become "uninsurable", is not something I'm in a rush to do.

WellWhat

12 posts

Geek

#3120840 27-Aug-2023 13:45

I'm late to the party here, my 2 cents on home energy monitoring would be to use an Iotawatt https://iotawatt.com/

Its what BRANZ use to do there energy monitoring for there surveys of energy usage in New Zealand https://d39d3mj7qio96p.cloudfront.net/media/documents/Info_pack_full_FINAL.pdf

Under the hood its an esp32 that has been cleverly designed for a cheaper energy monitor solution to what you would pay for commercially, using the current clamps around the wires you want to monitor

Even open source code if you want to change things yourself https://github.com/boblemaire/IoTaWatt and has exporters if you want to put it in influx then graph it with something like grafana

Will require a electrician to install the clamps in the switchboard and I have mine in another switchboard case beside it

Home assistant

The iotawatt interface webpage graph

phrozenpenguin

840 posts

Ultimate Geek

#3121012 27-Aug-2023 21:49

WellWhat:

I'm late to the party here, my 2 cents on home energy monitoring would be to use an Iotawatt https://iotawatt.com/

Its what BRANZ use to do there energy monitoring for there surveys of energy usage in New Zealand https://d39d3mj7qio96p.cloudfront.net/media/documents/Info_pack_full_FINAL.pdf

Under the hood its an esp32 that has been cleverly designed for a cheaper energy monitor solution to what you would pay for commercially, using the current clamps around the wires you want to monitor

Even open source code if you want to change things yourself https://github.com/boblemaire/IoTaWatt and has exporters if you want to put it in influx then graph it with something like grafana

Will require a electrician to install the clamps in the switchboard and I have mine in another switchboard case beside it

This looks good and more capable with 14 inputs, but is also at least double the price to even get started e.g. two inputs (compared to Shelly EM), and availability seems difficult (or am I missing something?). The fact the Shelly EM can also control a contactor was very helpful for my use case as well.

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#3121014 27-Aug-2023 22:07

Bewildered:
On my part I'm waiting for the non-lithium batteries to come....they will be safer, cheaper, and longer lived...and yes, it will be age until they come, but I'm in no hurry. The thought of strapping a lithium bomb to my house, especially if houses become "uninsurable", is not something I'm in a rush to do.

They're already here, they're LFP lithium not NMC lithium. A lot of newer solar batteries are LFP, NMC use for solar is dying out over time.

BlargHonk

147 posts

Master Geek

#3121045 28-Aug-2023 09:08

neb:
Bewildered:

On my part I'm waiting for the non-lithium batteries to come....they will be safer, cheaper, and longer lived...and yes, it will be age until they come, but I'm in no hurry. The thought of strapping a lithium bomb to my house, especially if houses become "uninsurable", is not something I'm in a rush to do.

They're already here, they're LFP lithium not NMC lithium. A lot of newer solar batteries are LFP, NMC use for solar is dying out over time.

LFP is still a lithium battery. That is the L in LFP

Bewildered

106 posts

Master Geek

#3121046 28-Aug-2023 09:13

I'm more waiting for something like this: https://www.polyjoule.com/

It will take a while for a house sized system to be available, but I can see something like this being a good fit for subfloor installation...

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#3121226 28-Aug-2023 14:36

BlargHonk:
neb: They're already here, they're LFP lithium not NMC lithium. A lot of newer solar batteries are LFP, NMC use for solar is dying out over time.

LFP is still a lithium battery. That is the L in LFP

Yes I know, that's why I said "LFP lithium", however they're a totally different chemistry and have the properties the OP wanted. I'd never strap 10kW of NMC to the side of the house but I do have 10kW of LFP there right now.

It's like saying you're avoiding H2O because H202 is dangerous, they've both got hydrogen and oxygen in them but they've very different.

1 | 2 | 3