If you own a Solarlog of Solar Data Systems, you get the Days_Hist.js from the Solarlog website. Go to your system on the homepage of Solarlog (same link as the input for Data-URL in the Data Logger information on PV-Log.com ) and add the extension "?file=days_hist.js" (without the quotes) to the URL. Subsequently, after loading the page, press Ctrl+S (Command S for Mac) to save the file to your hard drive. You can now use this file to import it to e.g. PV-Log.com.