Time to give electricity the flick?

Forums › Home Workshop DIY › Time to give electricity the flick?

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7 posts

Wannabe Geek

#1803976 20-Jun-2017 12:58

mentalinc:

Spot price forecast

Over the past fortnight, the spot price in the upper North Island has sat around 10.8 cents ($0.108).

Our forecast suggests that this will drop to 10.5 cents ($0.105) over the coming month.

We’ll keep updating you on the forecast as these dry conditions continue.

This seems a bit dubious given the futures market for July and August is suggesting prices will increase rather than decrease (to about 14c). Also spot prices today have been over 30c for most of the morning.

timmmay

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#1803985 20-Jun-2017 13:18

mattrix:

I think easycloud meant to say solid state relay?

Then you have to wire it all together and to your device, or your meter box - I don't think you're allowed to touch the meter box. A 10amp load is fairly heavy, do it wrong and there could be significant repercussions, like a house burning down.

I use a solid state relay, the 5V USB output from my TV controls the 12V feed to some fans that cool some equipment. Buying the parts in NZ it was actually kindof expensive, at least $50. I wouldn't mess with the mains.

easycloud

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#1803987 20-Jun-2017 13:23

mattrix:

I think easycloud meant to say solid state relay?

Yup :) Thanks for elaborating. Hard to type on a phone

mattrix:
That's not going to a D1, but actually just 5V from a USB port.
So, when we turn off one of our PCs at work at end of the day - it shuts down a bunch of our mains stuff.

Very clever!

mattrix:

I think the main issue is all the off the shelf devices that send and receive (poll) your data to the internet (via their servers).
So you can use there app "from anywhere". Also that they connect directly to your home WiFi.

My solution to that is simple, obliterate the factory firmware and use an open source alternative (NodeMCU OS) which allows you to write your own app layer (security by obscurity). I leverage the in-built MQTT library and HTTP modules to accomplish exactly what you described. I have a separate VLAN for all IoT devices so it doesn't interact with my home network at all. I didn't go as far as having a separate WiFi network.

example:

$ curl http://hotwater.iot.home/api/gpio/on

{ "status": "ok", "message": "Relay switched is now ON" }

$ curl http://hotwater.iot.home/api/gpio/off

{ "status": "ok", "message": "Relay switched is now OFF" }

My cheap APU (http://www.pcengines.ch/apu.htm) is the brains behind everything. It pulls the prices from Flick and decides what to switch on and off based on rules I setup.

It's not space-age technology, it's 2015 stuff. It's cheap, it's efficient, and it's already here.

It does take a bit of time to implement everything, particularly if you're doing everything from scratch, but I think it's well worth it. As before, happy to share the code if anyone wants to give it a try.

Sorry for the off-topicness

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mattrix

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#1804022 20-Jun-2017 13:48

@timmmay

Oh, I was talking about a hot-water switcher (Not switching power at the mains box).
I wouldn't muck around that.
But splicing a 4 plug power box and inserting a relay inline is pretty safe (as it's unplugged when you do it).

If you just want to measure your mains power usage, use a D1 + CT sensor.
It clips around the cable - so pretty safe to install yourself.

I'm doing this at the moment.

Except, I'm using a D1 + RF Transmitter.
Then on my NAS a RF Receiver.

This way, it's battery power will last much longer as you can turn off the WiFi on the D1 and then it's current usage is tiny.
You then put it to Deep Sleep between readings and it's power usage is "microscopic" - Bean.
If I had a power jack near the mains box - I would just use the WiFi of the D1.

It's so I can automatically set my free hour to the hour with the highest usage each day.
It doesn't need to be that accurate - as long as it's constantly in-accurate - then it will be accurate for the highest hour :)
But, I will probably try to calibrate it so it matches what ElectricKiwi say on their site.

timmmay

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#1804038 20-Jun-2017 14:08

Herald story.

"Vast swathes of New Zealand are set to be drenched as a complex low conjures up days of rain, gales and even snow for the South Island."

Maybe this will help with the spot prices. The Met Service forecast doesn't indicate a lot of rain, but fingers crossed.

mattrix

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#1804040 20-Jun-2017 14:14

I can imagine all the Flick customers doing "Rain Dances" around the country.
Or getting excited when the rain icon appears in the 10 day forecast.

Instead of "it's good for the farmers",
we will be saying "it's good for the Flick customers".

robertsona

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#1804046 20-Jun-2017 14:26

mattrix:

I can imagine all the Flick customers doing "Rain Dances" around the country.
Or getting excited when the rain icon appears in the 10 day forecast.

Instead of "it's good for the farmers",
we will be saying "it's good for the Flick customers".

I'm somewhat torn: I'm keen to see some significant dumps of good snow on the skifields, but also want lots of wet rain filling the high country lakes.

miked

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#1804120 20-Jun-2017 15:23

What are the legalities of putting a "self-made Wifi relay box" inline with the hotwater feed wire right by the hotwater tank?

Currently there is a box on wall there with a wire flex coming out to the Hot Water tank. Thinking of mounting another box next to it, or even putting my own stuff inside the existing box (which I guess currently just has a set of terminal inside to join the solid wires inside the wall out to the flex that runs to the element).

Assuming it is currently just a terminal block inside, and installed a suitable solid-state relay from Aliexpress and ran it from a ESP8266. Would the relay need to be certified? Would the installation need to be certified? Would it need to be wired in by an electrician? (If I put a small 5v PSU in there to run the ESP8266 I'd use a certified one)

Would it be better to get the electrician to install a high amperage socket a plug, and then inserted my own unit inline as a "plug-in module"? (so I could remove it again for maintenance and return the hotwater to being uncontrolled by taking my module out of line.)

Mike

easycloud

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#1804175 20-Jun-2017 16:48

miked:

What are the legalities of putting a "self-made Wifi relay box" inline with the hotwater feed wire right by the hotwater tank?

Currently there is a box on wall there with a wire flex coming out to the Hot Water tank. Thinking of mounting another box next to it, or even putting my own stuff inside the existing box (which I guess currently just has a set of terminal inside to join the solid wires inside the wall out to the flex that runs to the element).

Assuming it is currently just a terminal block inside, and installed a suitable solid-state relay from Aliexpress and ran it from a ESP8266. Would the relay need to be certified? Would the installation need to be certified? Would it need to be wired in by an electrician? (If I put a small 5v PSU in there to run the ESP8266 I'd use a certified one)

Would it be better to get the electrician to install a high amperage socket a plug, and then inserted my own unit inline as a "plug-in module"? (so I could remove it again for maintenance and return the hotwater to being uncontrolled by taking my module out of line.)

Mike

Hi Mike,

Whether or not you involve an electrician is entirely up to you. By law you have to, but many people don't (I'm one of them). If you're not 100% comfortable, get a sparky to help.

I would recommend the high-power (30A) wifi module such as this one:

https://www.aliexpress.com/item/DC-12V-Wireless-Wifi-Relay-Switch-Module-Mobile-Phone-Remote-Control-Timer-Self-Lock-High-Power/32787419865.html

I normally use one of these isolating switches to power the relay as well, it draws power straight from the mains. It's cheap and works well as I measured it to provide a steady 5V.

https://www.aliexpress.com/item/Precise-5V600mA-LED-Lamp-Isolating-Switch-AC-DC-220-to-5-12V-Power-Supply-Module-Y102/32702615312.html

Lastly, I would strongly recommend you fiddle around by attaching this to a lamp or some low-voltage device to get familiar with it. Once you're happy with the way it works and the smartphone app, you can get a sparky to install it. You're basically taking the load (red) wire and attaching it to the relay terminals in series - same as you would attach a normal light switch.

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michaelmurfy

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#1804195 20-Jun-2017 17:13

Hey guys best keep this on topic. I'd recommend starting up another discussion for the above.

Michael Murphy | https://murfy.nz
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easycloud

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#1804198 20-Jun-2017 17:37

michaelmurfy: Hey guys best keep this on topic. I'd recommend starting up another discussion for the above.

You're right, sorry.

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luckiestmanalive

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#1804199 20-Jun-2017 17:41

Did any of you see this post by Greg Size last month? https://www.energylink.co.nz/news/blog/should-i-stay-spot-or-switch

The key message to me is that there will be good years and bad years and it might therefore pay to save some of the money you make in the good years for the bad ones (unless you think you can switch away and back again at the right times).

Also, I think talk of a great exodus might be a little exaggerated - Flick increased its customer base by another 1,3000 customers last month (see www.emi.ea.govt.nz/r/wvyov).

Keep the innovative ideas for controlling load in response to price coming!

miked

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#1804200 20-Jun-2017 17:45

Thanks for the info. Already got some ESP8266 units that I can control with Blynk and can't ultimately programme myself too (like being able to grab the Flick price and respond accordingly), so makes sense to use those. I guess I can therefore get a bare "Songle 30A" relay and switch it myself. Thanks for the link to the power supply too.

Are you happy with Songle as a brand? I know there are reports of some SSRs being sold with lower ratings than the label declares.

Yeah I'd probably test it running a 2KW oil heater too, to make sure it can handle the load before getting installed in the box!

My sparky is very helpful so I'll have a chat with him.

Thanks

miked

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#1804201 20-Jun-2017 17:49

michaelmurfy: Hey guys best keep this on topic. I'd recommend starting up another discussion for the above.

Apologies. Posted my reply before I saw you comment! Was thinking we were getting a little off topic (although highly relevant to Flick users in particular!)

Sorry about that.

Mike

Aredwood

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#1804417 20-Jun-2017 23:06

easycloud:

Hi Mike,

Whether or not you involve an electrician is entirely up to you. By law you have to, but many people don't (I'm one of them). If you're not 100% comfortable, get a sparky to help.

I would recommend the high-power (30A) wifi module such as this one:

https://www.aliexpress.com/item/DC-12V-Wireless-Wifi-Relay-Switch-Module-Mobile-Phone-Remote-Control-Timer-Self-Lock-High-Power/32787419865.html

I normally use one of these isolating switches to power the relay as well, it draws power straight from the mains. It's cheap and works well as I measured it to provide a steady 5V.

https://www.aliexpress.com/item/Precise-5V600mA-LED-Lamp-Isolating-Switch-AC-DC-220-to-5-12V-Power-Supply-Module-Y102/32702615312.html

Lastly, I would strongly recommend you fiddle around by attaching this to a lamp or some low-voltage device to get familiar with it. Once you're happy with the way it works and the smartphone app, you can get a sparky to install it. You're basically taking the load (red) wire and attaching it to the relay terminals in series - same as you would attach a normal light switch.

Please don't use the above solid state relays for anything important. As quite alot of them are actually fake. And not only that but the fake ones are unlikely to have proper isolation between the low voltage side and the mains side. So under certain fault conditions your low voltage wiring could become live.

UL labs in the USA have reported that their marks have been used without permission. And here is a teardown video of one of them.

Also note that solid state relays do put out heat as part of normal operation. Approx 1 watt for every amp of current. So if you use a SSR to control a hot water cylinder, heater, or some other device that uses quite a bit of power. You need to attach the SSR to a decent heatsink.

For most applications a mechanical relay is still the best option. Jaycar sell a 30A mains rated relay that is also able to be used for switching inductive loads like motors. Part number SY-4040 cost $9.90 each or $8.90 each if you buy 10 or more. Aliexpress has lots of relay driver boards to interface logic level signals to relay coils, If you can't be bothered making your own relay driver circuits.

Also SSR allow a small leakage current through even when off approx 5mA. Which means that LED lights will glow dimly or flash as they try to start, and some very low power usage devices won't actually switch off. The best application for using SSR is for switching filament light bulbs. As some SSR have zero crossing turn on (check the datasheet!) Which means that the SSR waits for the mains cycle to reach 0V before switching on. This in turn limits the inrush current into the filament, compared to power getting switched on at the 360V peak of the mains cycle. This helps filament light bulbs to last longer.

Sorry about posting this mods, But I thought it was important to do so for safety. As there seems to be alot of watchers on this thread, who might not otherwise see info posted in another thread. Here is a thread from the Home Theatre forum about using SSR and making your own mains power controllers. Someone please tag me in that if more discussion appears in that thread please. Now to write up another Flick related post.

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