Solar Generation Monitoring with Home Assistant

Back in ?? we had Solar Panels installed for free on our roof by A Shade Greener, free as they take the money from the feed-in tariff, and yet we get to use the electricity that’s generated. Due to my wife’s ironing business, we consume a large amount of energy during the daytime, so having some of this for free, without any outlay is great.

However whilst the solar panels are connected up to their own smart meter, the data available via the A Shade Greener website is very basic, just daily data for the last month. I’ve been using our Owl Intuition-pv to measure our grid consumption, solar generation and overall electricity usage for many years. But as these use simple clamp meters they aren’t super accurate but good enough for me.

Recently a friend, another A Shade Greener customer and Home Assistant enthusiast asked for help to monitor his Solar generation and I was more than happy to help.

Electricity Meter

The meters installed by A Shade Greener are ISKRAEMECO ME382 (below left) whilst these meters can provide a serial interface via the “P1” port, this isn’t accessible without removing the secured lower cover and attaching an extra module. So instead in order to measure consumption, we can count flashes from the LED. Each 30ms pulse for every one-thousandth kWh generated.

Pulse Counting Sensor

Recently as part of Home Assistant launching their Energy Dashboard, they also release Home Assistant Glow, an ESPHome sensor for attaching to meters and counting pulses. So no need to develop my own solution when this will work just fine.

But always an opportunity to do some 3D printing 😉 I looked initially at a couple of designs that both had the light sensor and the MCU in separate enclosures connected by a short bundle of wires. I decided it didn’t need two different enclosures and could instead design an all in one solution. The model is available on Printable.com.

The sensor is using an ESP32 based MCU that I had to hand, (an ESP8266 would also be suitable and a little smaller) and a photo diode sensor module with a digital output. The photo diode sensor is connected with just 3 wires, 2 for power and one for signal. The entire sensor just needs power from a simple USB power supply.

I did briefly investigate the feasibility of powering the sensor with a battery/baterry pack, but the consumption would drain the battery very quickly. WiFi just isn’t the technology to use for low power sensors.

Energy Monitoring

With the sensor added via ESPHome into Home Assistant, the Energy dashboard now records the solar generated more accurately for my friend and they can use this data to determine if it’s worth investing in battery storage solution alogn with using the solar prediction to plan when to use certain energy hungry appliances.

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