Electricity price steering consumption using tellstick ...

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Electricity price steering consumption using tellstick ...

Postby PetriK » Fri Nov 10, 2017 7:16 pm

Found this nice software nordpool-ifttt by samuel rinnetmäki that sends messages to ifttt depending on nordpool prices. Did some finetuning for it like finding the cheapest and most expensive hours in a day (initially the software only worked with fixed prices which is nice but not really suitable to control hot water heater or EV charing). Basically you can set how many expensive and how many cheap hours you want to have in a day and the software controls thee rest. The old limits like 40c and 10c low are there still too. You can also limit how many consequent hours can be expensive or cheap e.g. to avoid a situation where house gets cold.

Currently the messages are sent to IFTTT which is then linked with telldus but I will rewrite the code to use local tellstick api just in case the internet live.telldus.com is down when have a bit more time. It runs on node.js (v8.9 is needed) so you can have it on pc, linux, apple or almost any device. I installed mine on Synology NAS. Dev environment I use is Atom which runs node as part of the coding desktop making development extremely easy.

Code is found here: https://github.com/PetriKarjalainen/nordpool-ifttt/tree/PetriK
NPM installation packages is found here: https://www.npmjs.com/package/petrikarjalainen-nordpool-ifttt

In case youre interested in co-implementing tellstick native api just drop me a line petrik (a) tikkari.net

Here is console log for todays prices and what IFTTT events are created:

[TAILING] Tailing last 15 lines for [all] processes (change the value with --lines option)
/root/.pm2/logs/index-out-0.log last 15 lines:
0|index | Running at (UTC) 2017-11-10T19:18:13.817Z
0|index | CET Expensive hours: 8,17,16,13
0|index | CET Cheap hours: 1,2,23,0
0|index | Scheduling: Friday 4:00 26.65 nordpool-price-normal
0|index | Scheduling: Friday 9:00 38.27 nordpool-price-high
0|index | Scheduling: Friday 10:00 32.1 nordpool-price-normal
0|index | Scheduling: Friday 14:00 36.9 nordpool-price-high
0|index | Scheduling: Friday 15:00 35.63 nordpool-price-normal
0|index | Scheduling: Friday 17:00 37.17 nordpool-price-high
0|index | Scheduling: Friday 19:00 36.52 nordpool-price-normal
0|index | Scheduling: Saturday 0:00 26.06 nordpool-price-low
Last edited by PetriK on Tue Nov 28, 2017 5:29 pm, edited 2 times in total.
Posts: 29
Joined: Fri Feb 24, 2017 6:00 am

Re: Electricity prices steering tellstick...

Postby PetriK » Thu Nov 23, 2017 11:44 am

Been using electricity prices to control various devices using Tellstick and IFTTT for a while now and its working like charm.

Here is a short writeup how it works in practice.

The program I wrote about in previous message runs a small linux server (Synology server) in nodejs daemon. It reads the hourly electricity prices from nordpool at midnight every day for following day. Below is a picture of hourly electricity prices from fingrid just to demonstrate the intraday variation of electricity prices.

When the program detects that electricity price is high it triggers an event to IFTTT. Below you can see triggered high and low events from IFTTT activity stream using webhooks service. The way how to setup a IFTTT webhook to receive messages and trigger Telldus devices is also described as part of the program setup tutorial

IFTTT is connected to Tellstick (Thanks Telldus dev team) and sets a device accordingly. In my case I have two correspoding devices programmed. These are actually dummy devices, if no hardware connected to these directly. Below you can see the devices which indicate that the price is normal. I have two devices only in use but at my home I will also implement price is low for hot water heater and electric car charging at night time. At summerhouse I can not do that due to the size of hot water heater and EV being charged only at 6A rate.

When the state of a telldus device changes it then triggers live.telldus.com event to e.g. connect hot water boiler off, hall radiator off, laundry machine off, electric car charger off. All these are devices which can be off for an hour or two without anyone even noticing a difference in quality of living at the house. Anyhow it makes a big change in electricity consumption like you can see in the picture below which shows what happened when electricity price high even was triggered and again what happened when electricity price low event was triggered. On the consumption curve you can see an immediate drop of electicity consumption when price high is triggered and consumption returning back to normal when event normal (typo says low) was triggered. The rest is normal variation in consumption different devices being turned on and off either automatically via live.telldus.com or manually.

The initial simulation tells that just by starting to use spot priced electricity I will save 250€/year at my summerhouse. This is based on downloading hourly prices and hourly consumption to excel and calculating the actuals fro this year. The software that steers the consumption adds additional 150€ saving per year - with current parameters. Of course you can choose how many consequent hours etc. so the actual savings I know after setting parameters to optimum level which keeps quality of living still high but provides maximum saving e.g. when not at the summerhouse. Btw. our summerhouse is 100+35sqm fully habitable also during the winter, so its like a normal house so we are talking about 400€ / 25% electricity cost saving annually with this mini project. So definately worth implementing not only at summerhouse but will implement similar system at my main house too.
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