Integration  Riemann sum integral
This integrations provides the Riemann sum of the values provided by a source sensor. The Riemann sum is an approximation of an integral by a finite sum.
The integration sensors are updated upon changes of the source. Fast sampling source sensors provide more accurate results. In this implementation, the default is the Trapezoidal method, but Left and Right methods can optionally be used.
Configuration
Adding Integration  Riemann sum integral to your Home Assistant instance can be done via the user interface, by using this My button:
If the above My button doesn’t work, you can also perform the following steps manually:

Browse to your Home Assistant instance.

In the sidebar click on Settings.

From the configuration menu select: Devices & Services.

In top of the screen click the tab: Helpers.

In the bottom right, click on the Create helper button.

From the list, search and select “Integration  Riemann sum integral”.

Follow the instruction on screen to complete the set up.
YAML Configuration
Alternatively, this integration can be configured and set up manually via YAML
as well. To enable the Integration sensor in your installation, add the
following to your configuration.yaml
file:
# Example configuration.yaml entry
sensor:
 platform: integration
source: sensor.current_power
Configuration Variables
An ID that uniquely identifies the integration sensor. Set this to a unique value to allow customization through the UI.
Round the calculated integration value to at most N decimal places.
Metric unit to prefix the integration result. Available units are k
, M
, G
and T
.
SI unit of time to integrate over. Available units are s
, min
, h
and d
.
In case you have an appliance which produces spikey consumption (like an on/off electrical boiler) you should opt for the left
method to get accurate readings.
The unit of source
together with unit_prefix
and unit_time
is used to generate a unit for the integral product (e.g. a source in W
with prefix k
and time h
would result in kWh
). Note that unit_prefix
and unit_time
are also relevant to the Riemann sum calculation.
Energy
An integration sensor is quite useful in energy billing scenarios since energy is generally billed in kWh and many sensors provide power in W (Watts).
If you have a sensor that provides you with power readings in Watts (uses W as unit_of_measurement
, device_class
of power
), then you can use the integration
sensor to track how much energy is being spent. Take the next manual YAML configuration as an example:
sensor:
 platform: integration
source: sensor.current_power
name: energy_spent
unit_prefix: k
round: 2
This configuration will provide you with sensor.energy_spent
which will have your energy in kWh, as a device_class
of energy
.