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Smart Plug


viper_za
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Hi All

 

Looking at ways to control and use my excess solar power during the day.

The wifi controlled smart plugs looks like the most convenient plug and play system available.

Does anybody know of similar plugs and prices locally?

http://www.miro.co.za/catalogue/edimax-smart-plug-wireless-remote-controlled-scheduled-power-switch/

 

Thanks

Thys

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Pet project I've been dreaming of for a long time. A plug that can measure power, turn it on and off, and that can report/be controlled by WiFi. Target price would be around R250. With the advent of the ESP8266, we're closer than ever...

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16 minutes ago, plonkster said:

Pet project I've been dreaming of for a long time. A plug that can measure power, turn it on and off, and that can report/be controlled by WiFi. Target price would be around R250. With the advent of the ESP8266, we're closer than ever...

How long plonkster ;)

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Just now, viper_za said:

How long plonkster ;)

You can get an ESP8266 from China for around R35. A current transformer to place around the live wire, probably around R30, I think R50 if you get them from RS. Those are the main parts you need. A couple of resistors, caps and discrete components, and a relay. So building one right now, you might be able to do it for around R200, excluding labour, and then you have to get it certified, SABS approved, all that nonsense, so you can buy it in the supermarket. So we're about halfway there. It might happen in the next 5 to 10 years. Guestimate.

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21 minutes ago, plonkster said:

You can get an ESP8266 from China for around R35. A current transformer to place around the live wire, probably around R30, I think R50 if you get them from RS. Those are the main parts you need. A couple of resistors, caps and discrete components, and a relay. So building one right now, you might be able to do it for around R200, excluding labour, and then you have to get it certified, SABS approved, all that nonsense, so you can buy it in the supermarket. So we're about halfway there. It might happen in the next 5 to 10 years. Guestimate.

Okay, I forgot something important. These things are pretty power hungry, up to 200mA when doing WiFi. So of course that is at something like 5V or 3.3V so in terms of watts it is not a problem, but it means you cannot use a cheap and nasy capacitive dropper to power it. You'll need a decent PSU as well. And fit it all into something that's not too much larger than a normal plug. Digikey says a small PSU like this will set you back 10USD. So I think lowest cost you could do it for now would be around R1k. My estimate of 5 to 10 years might be a little low :-)

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lol so the online unit at just over R1k is not sounding that bad.

I would need 4 atleast, eish man.

The plan is to use these things in the winter to heat the place up one room at a time every few minutes never running more than one at the same time.

How good are the panel heaters I know they are around 400 so with my 1800w array I can run 2 maybe 3 at the same time

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The price I sucked from my one opposable finger is based on what it might cost to bring it to market. You could possibly build it for less. If you're willing to improvise and recycle stuff (I love doing such things) it's even easier. For example, you may have several old phone chargers lying around. They are perfectly good switch-mode power supplies. Glue a small project box to the side with an ESP8266, a relay, and a current transformer, and you could likely do it for R200 a pop... if you're willing to wait a month or two for parts from China. The cheapest local one I've seen goes for around R100, and it's from a seller in Witbank who ships directly from China anyway...

What I'd do is buy 5 or 10 ESP8266's from allice1101983 on ebay and if/when they arrive... find something to do with them. Personally... I have an old 1-wire weather station lying in a box. I think I'm going to use my ESP8266 (I padded an order with one of these, because it was cheap) for that... once I find time for it.

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12 minutes ago, viper_za said:

How good are the panel heaters I know they are around 400 so with my 1800w array I can run 2 maybe 3 at the same time

I have a few of those as well. They are not bad, if you have proper insulation in your ceiling, they really do take the bite out of the air, and on a good sunny winters day I've also used one as a dump load :-)

In terms of cost, gas and electricity costs pretty much the same in terms of cost per kwh. Look up calorific content of LPG per kg, convert to kwh, divide cost of lpg per kg by that number, it's pretty close by present CoCT prices. Both appliances are darn near 100% efficient too. Electrical is much safer though. That's my two cents.

Gas is likely to be cheaper in future, I suspect. But is it cheaper than excess solar power you will normally just "throw away"? :-)

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5 minutes ago, The Terrible Triplett said:

How long will it take to save R1000 worth of electricity per device?

I found gas heaters more efficient that those panel heaters.

TTT in the long run using the Solar it should be cheaper than buying gas all the time

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Specced my system in winter, so I do not have excess bar in summer. :P

I like gas heaters, especially when a 9kg last between 1-2 months, bought at last years price.

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Just now, plonkster said:

In terms of cost, gas and electricity costs pretty much the same in terms of cost per kwh. Look up calorific content of LPG per kg, convert to kwh, divide cost of lpg per kg by that number, it's pretty close by present CoCT prices. Both appliances are darn near 100% efficient too. Electrical is much safer though. That's my two cents.

Gas is likely to be cheaper in future, I suspect. But is it cheaper than excess solar power you will normally just "throw away"? :-)

Yes that's the next step.

I am even willing to run two panels per room.

I should actually create a new thread with what I plan on my next upgrade phases :)

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11 minutes ago, viper_za said:

And then in the summer I plug in the AC and do the same ;)

Amen brother!!! 

I tried my AC, have the spare in summer, but it not being inverter based, my solar inverter takes a wee bit of strain till aircon settles.

So I figured, get another 2nd hand online 3kva UPS (like I had before the electrician blew it up) that can handle the aircon startup. 

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31 minutes ago, The Terrible Triplett said:

Seriously, my question re. paying +-R1000 for a smart plug. How long will it last, 1,2, 10 years?

Is it not wiser to rather use that cost and add more panels?

That's why the price has to come down to around R200 a piece :-)

 

Seriously, there's an entire market of things you can build and sell once the price comes down. Your average home owner is not going to buy an energy monitoring or saving device (and monitoring devices ARE saving devices if you think about it) for R1000 if he spends less than R1000 a month on electricity. But he might buy a R100 device...

 

Now imagine if you could make energy monitoring cheap, so cheap that even beneficiaries of social grants that struggle to make ends meet and are on the the lifeline tariff (at around R1/kwh iirc) see sense in buying one because it will save them money. Then we can seriously cause a drop in Eskom's sales... :-P

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