Hi Chandytech as Moe posted the solution resistor divider a Zener diode usage you can go for that. A voltage divider calculator like this can, of course, help you for doing calculations. http://www.voltagedividercalculator.com/
Meanwhile, you also need a Raspberry Pi model B, an SD card of 4GB, RS 232 adapter matching your inverter a Wifi adapter, a USB hub and SD card reader. I recently checked a tutorial by Steffen who shared the method to upload data from Growatt inverter to some website using the Raspberry Pi, Here I am quoting the ingredients for the project:
1 Raspberry Pi Model B
1 SD card (4 GB or more) - preferable Class 10
1 microUSB power adapter
1 USB-RS232 adapter with the number of RS232 ports that equals your number of inverters. If you have more than 1 inverter you might additional need an extension RS232 cable. Do not buy these too cheap - cables with PL2303 chips seems ok.
1 USB WiFi adapter or Ethernet cable
1 USB keyboard and mouse
1 USB hub (if you easily need to setup the WiFi adapter up on an encrypted network)
1 SD card reader (you might have one in your laptop)
Monitor/TV with hdmi or composite video, along with cable.
You can learn full details about the project here: http://fixedbycode.blogspot.com/2014/04 ... owatt.html
This project might not be exactly the one you are looking for but hopefully you can lump Moe voltage divider solution with this to acheive something.