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Monitoring Home Power Consumption for less than $25

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Re: Monitoring Home Power Consumption for less than $25

#81

Post by SergeAx »

orf wrote: post #79
SergeAx wrote: post #77

Earlier quoted context omitted.

Our most talkative meters are currently broadcasting 4 packets of data per hour. Water meters with autonomous power are limited to one or two (for central hot water supply) packets per day. With all the randomness added collecting data for successful key bruteforcing will take months or even years. On the other hand, using 64 bits allows us to use 16- or even 8-bit microcontrollers, which is beneficial to power consu…

Still, the comment above still stands. Not sure about the key bruteforcing estimates, surely a couple of days of readings would be enough. Are the keys stored on the devices? Is it a shared key?

Every device has it's own unique keys - one for transmitting data and another for receiving commands. They are burned with firmware in production. If you are interested in bruteforcing - I can send you two weeks worth of my home water meters' data packets to play with :) See, the CRC is calculated for encrypted data, so there is no way to know if the guessed key is correct.

Re: Monitoring Home Power Consumption for less than $25

#82

Post by matthewmacleod »

SergeAx wrote: post #80
Joe8Bit wrote: post #54

Earlier quoted context omitted.

Interestingly, in the UK utilities are using GSM SIM cards in Smart Meters, and a mixture of SMS and data to monitor/send electricity usage.

Those smart meters should be outrageously expensive both in production and running. Are utilities government-sponsored in UK?

They’re not.

I’m confused why you think this would be particularly expensive, though; the components aren’t that expensive, and neither is data service for the minimal data the meter will send. I would imagine it’s more expensive than a PLC or general radio solution, but on the other hand it’s got the benefit of requiring minimal new infrastructure.

Re: Monitoring Home Power Consumption for less than $25

#83

Post by [deleted] »

evan_ wrote: post #74
problems wrote: post #4

Nice method, but for future record you don't really need to mess with mains to hook up Sense or OpenEnergyMonitor, they use inductive current clamps which work by detecting the field around the a single terminal of your incoming mains. Pretty much as safe as it gets with this stuff.

Sense actually has you install a 240v breaker in addition to the clamps. https://sense.com/help/installguide.pdf https://youtu.be/qh9m2xuDrW4

[deleted]

Re: Monitoring Home Power Consumption for less than $25

#84

Post by [deleted] »

alanfranzoni wrote: post #50
inglor wrote: post #34

It's weird that he didn't give the ELK stack a chance. Kibana would be awesome at graphing this and data ingestion would also be very simple. Very useful for automatically generating graphs based on data. Would have automated the whole "writing PHP + jQuery + SQLITE3" part entirely - and consume the JSON directly and created visualizations based on that.

Do you realize that an ELK stack has an enormous overhead comparing to a bare php script? Your idea may be good for a large-scale monitoring deployment, but it's totally overengineered for a simple, in-house monitoring system.

[deleted]

Re: Monitoring Home Power Consumption for less than $25

#85

Post by ris »

SergeAx wrote: post #77
mrb wrote: post #69

Earlier quoted context omitted.

That's great, but using a 64-bit key in 2017 isn't "taking security seriously". Especially if you are designing meters that will have a lifespan of 10+ years, therefore must be secure until 2027 and beyond.

Our most talkative meters are currently broadcasting 4 packets of data per hour. Water meters with autonomous power are limited to one or two (for central hot water supply) packets per day. With all the randomness added collecting data for successful key bruteforcing will take months or even years. On the other hand, using 64 bits allows us to use 16- or even 8-bit microcontrollers, which is beneficial to power consu…

> Of four recources commonly metered in Russia - electricity, water, gas and heat

When you say "heat" - is this steam from a combined heat & power plant? I was aware these were quite widespread in Russia but didn't know they were metered.

Re: Monitoring Home Power Consumption for less than $25

#86

Post by mkempe »

edejong wrote: post #40

Since the transmission is not authenticated, I wonder if it is possible the shield or interfere with your own transmission and broadcast a fake report instead.

Or the reports of others in the neighborhood... How does the power utility collect these reports?

Re: Monitoring Home Power Consumption for less than $25

#87

Post by SergeAx »

matthewmacleod wrote: post #82
SergeAx wrote: post #80

Earlier quoted context omitted.

Those smart meters should be outrageously expensive both in production and running. Are utilities government-sponsored in UK?

They’re not. I’m confused why you think this would be particularly expensive, though; the components aren’t that expensive, and neither is data service for the minimal data the meter will send. I would imagine it’s more expensive than a PLC or general radio solution, but on the other hand it’s got the benefit of requiring minimal new infrastructure.

GSM assembly with SIM holder costs about $5 in a mass-production-wise quantities. I don't know about UK, but here in Russia typical "dumb" resource meter costs between 10 and 30 USD. Smart meter could not be more than 2x expensive to be competitive. So you should squeeze all other functionality into $5 production cost just to have zero margin, and you should completely forget about autonomy. And I don't even want to start ranting about running costs of GSM.

This is what LPWAN like LoRa, Sigfox, NbIoT and Nwave are made for.

Re: Monitoring Home Power Consumption for less than $25

#88

Post by gh02t »

matthewmacleod wrote: post #82
SergeAx wrote: post #80

Earlier quoted context omitted.

Those smart meters should be outrageously expensive both in production and running. Are utilities government-sponsored in UK?

They’re not. I’m confused why you think this would be particularly expensive, though; the components aren’t that expensive, and neither is data service for the minimal data the meter will send. I would imagine it’s more expensive than a PLC or general radio solution, but on the other hand it’s got the benefit of requiring minimal new infrastructure.

Considering the alternative is employing a person who has to go around and read every meter versus the very low cost of a GSM radio I think it very clearly makes sense cost wise.

Re: Monitoring Home Power Consumption for less than $25

#89

Post by SergeAx »

ris wrote: post #85
SergeAx wrote: post #77

Earlier quoted context omitted.

Our most talkative meters are currently broadcasting 4 packets of data per hour. Water meters with autonomous power are limited to one or two (for central hot water supply) packets per day. With all the randomness added collecting data for successful key bruteforcing will take months or even years. On the other hand, using 64 bits allows us to use 16- or even 8-bit microcontrollers, which is beneficial to power consu…

> Of four recources commonly metered in Russia - electricity, water, gas and heat When you say "heat" - is this steam from a combined heat & power plant? I was aware these were quite widespread in Russia but didn't know they were metered.

No, not steam, just hot water. Yes, mostly from heat & power plants, but sometimes from gas-powered local boiler plants. They are metered on per-building basis, but there's technical possibility to install individual meter and pay only for actual consumption.

Re: Monitoring Home Power Consumption for less than $25

#90

Post by matthewmacleod »

SergeAx wrote: post #87
matthewmacleod wrote: post #82

Earlier quoted context omitted.

They’re not. I’m confused why you think this would be particularly expensive, though; the components aren’t that expensive, and neither is data service for the minimal data the meter will send. I would imagine it’s more expensive than a PLC or general radio solution, but on the other hand it’s got the benefit of requiring minimal new infrastructure.

GSM assembly with SIM holder costs about $5 in a mass-production-wise quantities. I don't know about UK, but here in Russia typical "dumb" resource meter costs between 10 and 30 USD. Smart meter could not be more than 2x expensive to be competitive. So you should squeeze all other functionality into $5 production cost just to have zero margin, and you should completely forget about autonomy. And I don't even want to…

You’re ignoring the marginal cost of requiring meter reads with dumb meters, though, let alone any other benefits that the meter might offer.

I agree that the WAN tech is perhaps more suitable in theory, but that ignores the fact that there is already a ubiquitous GSM network in place.

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