Design question on power monitoring system

I have a power monitoring system where I store electrical current for a several outlets every minute. I also have power price stored every hour.

I have designed the InfluxDB data structure so that both the amp values and price is in the same measurement. To identify which value is which I use the _field column and tag the price with “price” and apms with “value” (in hindsight I should have chosen “amps”). Further on to identify the current sensors I have a location and sensor tag. The location tag can be either “home” or “garage” and the sensor tag can be “current_sensor_0” through “current_sensor_3”

I have thaught a lot about this design, but I am not sure if it is a good design. The end goal is to display power use in Grafana. I have managed to show a graph with these data.

However, I would also like to display a bar graph summing up the power used in a timeframe for each current sensor and multiply it with the power price every hour. This is where I struggle. I know too little about Flux (joining, summing, and grouping) and I also wonder if my data structure design is stupid

Help is appreciated!

BTW: I had this up and running using MySQL. I chose this back then because i knew SQL but with two years of data the DB it was tremendously slow! So therefore I want to switch to InfluxDB