Having some troubles to recover a "Volkszähler" system (server doesn't exists any more), I decided to build my own Smart Meter system,  user friendly and simple to maintenance.

<strong>The concept:</strong> S0 Impulses are counted via interrupt on a microcontroller (ESP32) and sent to a Web-server running on a Rasperry Pi. Every time, after 60 seconds, three counter values (for each phase of the power lines) are written into a Round Robin Database (RRD) file. The graph function of RRDtool is used to present this data to a human viewer via Web-Browser.

<img class="alignnone size-full wp-image-754" src="https://johann.langhofer.net/wp-content/uploads/2021/04/Screenshot-2021-04-03-232926.jpg" alt="" width="1109" height="458" />

<strong>The hardware configuration: </strong>ESP32 -&gt;(WLAN)-&gt;RPI2