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81 lines
2.9 KiB
ReStructuredText
81 lines
2.9 KiB
ReStructuredText
Non-Invasive Power Meter
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========================
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.. seo::
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:description: Instructions for hacking your power meter at home to measure your power usage.
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:image: power_meter.jpg
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So an essential part of making your home smart is knowing how much power it uses over
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the day. Tracking this can be difficult, often you need to install a completely new
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power meter which can often cost a bunch of money. However, quite a few power meters
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have a red LED on the front that blinks every time that one Wh has been used.
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The simple idea therefore is: Why don't we just abuse that functionality to make the power-meter
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IoT enabled? We just have to hook up a simple photoresistor in front of that aforementioned
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LED and track the amount of pulses we receive. Then using ESPHome we can instantly have
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the power meter show up in Home Assistant 🎉
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Hooking it all up is quite easy: Just buy a suitable photoresistor (make sure the wave length
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approximately matches the one from your power meter). Then connect it using a simple variable
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resistor divider (see `this article <https://blog.udemy.com/arduino-ldr/>`__ for inspiration).
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And... that should already be it :)
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.. figure:: images/power_meter-header.jpg
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:align: center
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:width: 80.0%
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.. note::
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Some energy meters have an exposed S0 port (which essentially just is a switch that closes), if
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that is the case the photodiode can be replaced with the following connection.
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.. code-block::
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S0 ------------ VCC
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S0 --+-- 10k -- GND
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. |
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. +--------- GPIO12
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For ESPHome, you can then use the
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:doc:`pulse counter sensor </components/sensor/pulse_counter>` using below configuration:
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.. code-block:: yaml
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sensor:
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- platform: pulse_counter
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pin: GPIO12
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unit_of_measurement: 'kW'
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name: 'Power Meter'
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filters:
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- multiply: 0.06 # (60s/1000 pulses per kWh)
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Adjust ``GPIO12`` to match your set up of course. The output from the pulse counter sensor is in
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``pulses/min`` and we also know that 1000 pulses from the LED should equal 1kWh of power usage.
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Thus, rearranging the expression yields a proportional factor of ``0.06`` from ``pulses/min`` to
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``kW``.
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And if a technician shows up and he looks confused about what the heck you have done to your
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power meter, tell them about ESPHome 😉
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.. note::
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Photoresistors often have a bit of noise during their switching phases. So in certain situations,
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a single power meter tick can result in many pulses being counted. This effect is especially big on
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ESP8266s. If you're experiencing this, try enabling the ``internal_filter:`` filter option:
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.. code-block:: yaml
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sensor:
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- platform: pulse_counter
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# ...
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internal_filter: 10us
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See :doc:`/components/sensor/total_daily_energy` for counting up the total daily energy usage
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with these ``pulse_counter`` power meters.
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See Also
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--------
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- :doc:`/components/sensor/pulse_counter`
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- :ghedit:`Edit`
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