added shelly example

README.md

@@ -74,9 +74,7 @@ InfluxDb is running here: http://localhost:8086/ (you have to create an initial
 You can login to Grafana: http://localhost:3000/login (admin:admin)
 
 
-## Usage
-
-
+## Examples and set-up
 
 ### Setting up a simple flow in Node-RED
 
@@ -86,10 +84,16 @@ A simple introduction to Node-RED can be found - along with the nodes / the code
 
 A more sophisticated exampe on how to connect Node-RED to influx is also available in [this repository](./docs/flow/docs/node-influx.md).
 
+
 ### Setting up Grafana
 
 Have a look at the [HowTo in this repository](./docs/dashboard/README.md).
 
+
+### Attaching a Shelly plug
+
+As an example you can use a Shelly plug flashed with Tasmota and feed MQTT data with Node-RED into InfluxDB and visualize it with Grafana. Have a look, [here](./docs/shelly/README.md).
+
 ## Contribution
 
 Feel free to open an issue for bugs, feature requests, or questions. Contributions are welcome.

docs/shelly/README.md

@@ -0,0 +1,55 @@
+# Shelly Plug (S)
+
+Shelly Plugs S are quite cheap but relatively accurate to measure power consumptions less than 2.5 kW.
+
+![Shelly Plug](https://shelly.hr/wp-content/uploads/2020/11/shelly_plug_s_1-1.jpg)
+
+In our [smart-energy-montior](https://code.curious.bio/curious.bio/smart-energy-monitor) project we already have set up a Shelly using Tasmota, on Open Source alternative firmware, that also runs on various other consumer off the shelf devices.
+
+
+## InfluxDB Bucket
+
+In Influx I created a bucket called `shelly`in InfluxDB, so we can store the messages in this bucket.
+
+### Node-RED
+
+I create a usual flow in Node-RED. A MQTT node fetches the values. 
+
+![Node-RED](./docs/images/node-red.png)
+
+The message is fed into a filter function to only store usefull information:
+
+```
+return  {
+    payload: {
+        power: Number(msg.payload.ENERGY.Power),
+        voltage: Number(msg.payload.ENERGY.Voltage),
+        current: Number(msg.payload.ENERGY.Current)
+    }
+};
+````
+
+The `payload` will be stored in InfluxDB in the bucket "shelly".
+
+### InfluxDB Data Explorer
+
+In Influx DB Data Explorer you can query the stored data.
+
+![Data Explorer](./docs/images/data-explorer.png)
+
+The query created by Data Explorer looks like that:
+
+```
+from(bucket: "shelly")
+  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
+  |> filter(fn: (r) => r["_measurement"] == "msg")
+  |> filter(fn: (r) => r["_field"] == "power" or r["_field"] == "voltage" or r["_field"] == "current")
+  |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)
+  |> yield(name: "mean")
+```
+
+### Grafana
+
+Using this query you can crate a dashboard in Grafana.
+
+![Grafana](./docs/images/grafana.png)