In my previous post I explained how I created a Home Assistant entity to track the daytime/nighttime costs of my electricity. However, that is only half the story. Let’s back up to where this started.

I got into home automation a few years ago - I have a few Google Home devices, the IKEA TRÅDFRI gateway and a bunch of smart lightbulbs. The integration between all these was pretty good, so I didn’t think I needed another system so I stayed away from Home Assistant - until I finally caved and gave it a try. I set it up on a dedicated raspberry Pi 4, and needless to say it is amazing. Not only does it have integrations for pretty much everything, but once I also added a zigbee dongle, this unlocked a bunch of workflows that were not available through the existing IKEA or Google Assistent apps.

I started being interested in monitoring my electricity once I discovered that my apartment’s electricity meter has a serial port that spits out live data called a P1/HAN port. Apparently all electricity meters in the nordic countries need to have it. Sweet! After months of deliberations I decided to buy the official P1 to MQTT adapter with WiFi support. Connecting it to Home Assistant was straightforward - even though I did have to create an extra helper for the incoming data.

In any case, now that I had my electricity consumption in the dashboard, obviously I also wanted to track the costs. As I mentioned in my previous post, my electricity supplier, Nacka Energi, has a fixed night/day rate, that was easy enough to hardcode into an entity. However, my electricity “provider”, GodEl has a variable electricity cost on top of the fixed rate.

Fun fact: GodEl is a great electricity company that donates all their profits to charity. Nice 👍

In any case, the variable electricity rate doesn’t seem to be available on any public endpoint, but I can view it in the GodEl app. It was an easy few steps to fire up HTTPToolkit, intercept all network requests, and see what’s going on. It was easy enough to put that into a python script, and try to run it in HA. To my surprise, importing requests failed, and it took quite a bit of googling to figure out that what I needed was the AppDaemon integration, and then I could run the script in an isolated environment.

In any case, here’s my script.

Show me the Python code! 
import requests
from datetime import datetime, timezone, timedelta
import json
import os
import appdaemon.plugins.hass.hassapi as hass

class SpotPrice(hass.Hass):
	def initialize(self):
		self.run_every(self.get_spot_price, "now", 900)  # Run every 15 minutes

	def read_bearer_token(self, file_path):
		with open(file_path, 'r') as file:
			return file.read().strip()

	def read_json_data(self, file_path):
		if os.path.exists(file_path):
			with open(file_path, 'r') as file:
				return json.load(file)
		return None

	def save_json_data(self, file_path, data):
		with open(file_path, 'w') as file:
			json.dump(data, file, indent=4)

	def find_current_spot_price(self, spot_prices):
		current_time = datetime.now(timezone.utc)
		current_time_rounded = current_time.replace(minute=0, second=0, microsecond=0)
		for price in spot_prices:
			price_time = datetime.fromisoformat(price['date'][:-1]).replace(tzinfo=timezone.utc)
			if current_time_rounded == price_time:
				return price['value']
		return None

	def is_file_newer_than_one_hour(self, file_path):
		if os.path.exists(file_path):
			file_mod_time = datetime.fromtimestamp(os.path.getmtime(file_path), timezone.utc)
			return datetime.now(timezone.utc) - file_mod_time < timedelta(hours=1)
		return False

	def get_current_day_times(self):
		current_time = datetime.now(timezone.utc)
		start_time = current_time.replace(hour=0, minute=0, second=0, microsecond=0).isoformat()
		end_time = (current_time + timedelta(days=1)).replace(hour=0, minute=0, second=0, microsecond=0).isoformat()
		return start_time, end_time

	def get_spot_price(self, kwargs):
		bearer_token = self.read_bearer_token('/config/bearer_token.txt')
		json_file_path = '/config/spot_prices.json'
		current_time = datetime.now(timezone.utc)

		if self.is_file_newer_than_one_hour(json_file_path):
			data = self.read_json_data(json_file_path)
			if data is not None:
				spot_prices = data['data']['spotPrices']
				current_spot_price = self.find_current_spot_price(spot_prices)
				if current_spot_price is not None:
					self.set_state('sensor.spot_price', state=current_spot_price, attributes={
						'unit_of_measurement': 'SEK/kWh',
						'friendly_name': 'Spot Price',
						'value_with_vat': current_spot_price * 1.25
					})
					return

		start_time, end_time = self.get_current_day_times()
		url = "https://godel.production.getbright.se/v3/data/spotprices/delivery-area/SE3"
		params = {
			"startTime": start_time,
			"endTime": end_time,
			"interval": "hour"
		}
		headers = {
			"accept": "application/json",
			"Accept-Encoding": "gzip",
			"authorization": f"Bearer {bearer_token}",
			"Connection": "Keep-Alive",
			"content-type": "application/json",
			"Host": "godel.production.getbright.se",
			"User-Agent": "okhttp/4.9.2"
		}

		response = requests.get(url, headers=headers, params=params)
		if response.status_code == 200:
			data = response.json()
			self.save_json_data(json_file_path, data)
			spot_prices = data['data']['spotPrices']
			current_spot_price = self.find_current_spot_price(spot_prices)
			if current_spot_price is not None:
				self.set_state('sensor.spot_price', state=current_spot_price, attributes={
					'unit_of_measurement': 'SEK/kWh',
					'friendly_name': 'Spot Price',
					'value_with_vat': current_spot_price * 1.25
				})
			else:
				self.set_state('sensor.spot_price', state='unavailable', attributes={
					'unit_of_measurement': 'SEK/kWh',
					'friendly_name': 'Spot Price'
				})
		else:
			self.log(f"Request failed with status code {response.status_code}")


The app also has a reauthentication workflow, but so far the script keeps working so I didn’t need to worry about that until now. I’ll try to fix it once it starts failing 🙂.

Here’s the YAML for my new helper entity that includes both the fixed and spot price.


{% set current_time = now().time() %}
{% set start_time = now().replace(hour=6, minute=0, second=0, microsecond=0).time() %}
{% set end_time = now().replace(hour=22, minute=0, second=0, microsecond=0).time() %}
{% set spot_price = states('sensor.spot_price') | float %}
{% set daytime_price = 0.6550 %}
{% set nighttime_price = 0.4912 %}
{% if start_time <= current_time < end_time %}
  {{ spot_price + daytime_price }}
{% else %}
  {{ spot_price + nighttime_price }}
{% endif %}
  • Unit of measurement: SEK/kWh
  • Device class: Balance
  • State class: Total

So here’s the final chart of the electricity cost in my area. I find it quite useful for deciding when’s the best time to run the dishwasher or even just to see how it affects the overall cost of my electric bill.