Cost sensor not working with negative energy prices

[JohanEikelenboom]

Version of the custom_component

Using version: V1.1.0

Describe the bug

As you can see in the attached screenshot, the energy price between was negative between 12:00 and 15:00.

During this time, I charged my EV (see the screenshot with the daily energy import between 13:00 and 17:00).

To my surprise, the cost remained the same between 10:30 (as expected due to solar returning energy) and 15:00. I would expect the daily cost would decrease between 12:00 and 15:00 since I turned off the solar panels and started charging my EV at 13:00.

[zeronounours]

Hello, I've dig a bit into your problem. The cost sensor do accept negative prices :

However, utility meters do not (by default). As your graph shows a reset at noon, I'm assuming you're showing the meter of the cost. Is that correct?

In that case, you need to enable the net_consumption option: https://www.home-assistant.io/integrations/utility_meter/#net-consumption. You can use the same option for the energy_meter (see https://github.com/zeronounours/HA-custom-component-energy-meter/blob/main/README.md#utility-meter-configuration-variables):

energy_meter:
  electricity:
    source: sensor.energy
    name: Daily energy
    cycle: daily
    price_entity: sensor.current_energy_price
    net_consumption: true