I have the below `stl()` (with `s.window="periodic"`) decomposition plot of a time series which I would like to analyse and model. The time series is hourly with data from Dec 2017 up until 17 Sep 2018. I am not very sure on how to interpret the trend. Does it mean that my data has no overall trend? What does the "wiggly" trend line ,like so, indicate?  

[![stl_decomp][1]][1]

Apart from this, I plotted the ACF and the PACF plots for the series (without differencing or transforming) and I have the below plot and I cannot seem to understand what the the ACF plot is telling me.

[![acf_plot][2]][2] 

Any help on this is much appreciated!

  [1]: https://i.sstatic.net/9Gwdu.png
  [2]: https://i.sstatic.net/pdeZL.png