Bulb is controlled by Home Assistant. It just gets the energy prices via integration (Nordpool from HACS) and then there are 3 automations for changing the color. In the "Stock price" subscription model the price is different for every hour and they are announced the day before. Anyway it's not always practical at look at the prices and memorize the cheap hours. So the light helps to avoid using unnecessary lights and appliances when the electricity is expensive.
