Introduction
European Power Exchange (EPEX SPOT) operates day-ahead power markets for Austria, Belgium, Denmark, Finland, France, Germany-Luxemburg, Great Britain, the Netherlands, Norway, Poland, Sweden and Switzerland. These Day-Ahead markets are organised through an auction process, matching once a day supply and demand curves and thus fixing prices in an anonymous, yet transparent and secured manner. Members of the Exchange enter their orders for hourly quantities of power into the order book which is closed on 11 am for Switzerland and on 12 pm for all other markets. EPEX SPOT calculates the offer and demand curves and their intersection for each hour of the following day. Results are published from 9.30 am GMT (Great Britain), 11.10 am (Switzerland) and 12.55 pm (all other markets) [source: Wikipedia].
In this tutorial we will create an openHAB HTTP URL Thing epexspot market data that provides day-ahead prices (€/MWh) for each hour interval.
This offers the possibility to validate the prices provided by the Tibber Binding and the aWATTar Binding against the ‘real ones’.
Software requirements
HTTP Binding
RegExTransformation Service
XPath Transformation Service
Setup
Things → Add → HTTP Binding → HTTP URL Thing
Base URL:
https://www.epexspot.com/en/market-data?market_area=DE-LU&modality=Auction&sub_modality=DayAhead&product=60&data_mode=table
Replace DE-LU with your power market area:
Do not create the Thing before 1 pm and do not change the update interval (86400 s = 1 day).
UID: http:url:109294a36b
label: epexspot market data
thingTypeUID: http:url
configuration:
authMode: BASIC
ignoreSSLErrors: false
baseURL: https://www.epexspot.com/en/market-data?market_area=DE-LU&modality=Auction&sub_modality=DayAhead&product=60&data_mode=table
delay: 0
stateMethod: GET
refresh: 86400
commandMethod: GET
timeout: 3000
bufferSize: 2048
channels:
- id: data_description
channelTypeUID: http:string
label: data_description
description: ""
configuration:
stateTransformation: REGEX:.*?(<h2>.*?</h2>).*∩XPATH://h2
- id: "00"
channelTypeUID: http:number
label: "00"
description: ""
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[1]/td[4]
- id: "01"
channelTypeUID: http:number
label: "01"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[2]/td[4]
- id: "02"
channelTypeUID: http:number
label: "02"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[3]/td[4]
- id: "03"
channelTypeUID: http:number
label: "03"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[4]/td[4]
- id: "04"
channelTypeUID: http:number
label: "04"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[5]/td[4]
- id: "05"
channelTypeUID: http:number
label: "05"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[6]/td[4]
- id: "06"
channelTypeUID: http:number
label: "06"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[7]/td[4]
- id: "07"
channelTypeUID: http:number
label: "07"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[8]/td[4]
- id: "08"
channelTypeUID: http:number
label: "08"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[9]/td[4]
- id: "09"
channelTypeUID: http:number
label: "09"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[10]/td[4]
- id: "10"
channelTypeUID: http:number
label: "10"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[11]/td[4]
- id: "11"
channelTypeUID: http:number
label: "11"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[12]/td[4]
- id: "12"
channelTypeUID: http:number
label: "12"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[13]/td[4]
- id: "13"
channelTypeUID: http:number
label: "13"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[14]/td[4]
- id: "14"
channelTypeUID: http:number
label: "14"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[15]/td[4]
- id: "15"
channelTypeUID: http:number
label: "15"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[16]/td[4]
- id: "16"
channelTypeUID: http:number
label: "16"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[17]/td[4]
- id: "17"
channelTypeUID: http:number
label: "17"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[18]/td[4]
- id: "18"
channelTypeUID: http:number
label: "18"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[19]/td[4]
- id: "19"
channelTypeUID: http:number
label: "19"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[20]/td[4]
- id: "20"
channelTypeUID: http:number
label: "20"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[21]/td[4]
- id: "21"
channelTypeUID: http:number
label: "21"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[22]/td[4]
- id: "22"
channelTypeUID: http:number
label: "22"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[23]/td[4]
- id: "23"
channelTypeUID: http:number
label: "23"
description: null
configuration:
stateTransformation: REGEX:.*?(<tbody>.*?</tbody>).*∩XPATH://tr[24]/td[4]
- id: delivery_date
channelTypeUID: http:datetime
label: delivery_date
description: ""
configuration:
stateTransformation: REGEX:.*?data-head="(.*?)".*∩REGEX:s/(\d\d)\.(\d\d)\.(\d\d)/20$3-$2-$1/g
- id: last_update
channelTypeUID: http:string
label: last_update
description: ""
configuration:
stateTransformation: REGEX:.*?Last\supdate\:(.*?)<.*
- component: oh-label-card
config:
title: epexspot market data
action: group
actionGroupPopupItem: epexspotmarketdata
item: epexspotmarketdata_data_description
fontSize: 7.5pt
Limitations
- AFAIK the HTTP Binding cannot be instructed to run at a specific time of day. If openHAB is restarted and the day-ahead prices are not yet available, the market data update will fail. The transformation of the RegEx/XPath Transformations into an openHAB Rule or an openHAB Binding is left to the reader as an exercise.
- If the structure of the HTML page changes, the Thing will probably break (but should be easy to fix).
- Please note that the HTML page is syntactically wrong.
That’s the main reason for concatenating a RegEx and an XPath Transformation.