To communicate with a RS485 solar inverter, WebSolarLog needs a RS485<>USB converter. Almost every RS485 converter is compatible, and you can find cheap ones at DealExtreme.com or Ebay.com.
We tested a couple of RS485 converters on the RaspberryPi. Based on these tests, we advise to buy a converter with an PL2303 or CH340T chipset.
If you have any questions, suggestions or what so ever regarding this post, feel free to post on our google support forum: