Update Growatt.md

Author: HotNoob

documentation/devices/Growatt.md

@@ -5,6 +5,10 @@
 2. for models with a DB9 port a DB9 RS232 adapter is required. "Before use RS232 communication, you should make sure the follow PIN1 and PIN2 are OFF"
 3. Connect cable to wifi dongle port; if a alternative usb port exists, try connecting to that one first. 
 
+Optional hardware:
+ADUM3160 chipset / USB isolator. The growatt inverter's usb port has a power issue that can effect reliablilty; using an isolator will help mitigate this problem.
+https://www.aliexpress.com/item/1005002959825296.html?spm=a2g0o.order_list.order_list_main.5.51c618021n8SGf
+
 ## Configuration
 Follow configuration example for ModBus RTU to MQTT
 https://github.com/HotNoob/PythonProtocolGateway/wiki/Configuration-Examples#modbus-rtu-to-mqtt