Simple answer: Select "Wifi Reload" from the front panel menu.
Just had solar PV installed and it's sweet!
After a week I got round to setting up the wifi on inverter.
To explain - if the inverter is within range of your home wifi router, you can set it up so that the inverter sends info to the goodwe portal (http://www.goodwe-power.com) website so you can monitor the performace of the panels by logging into the site.
Anyway - my first problem was that the inverter is supposed to provide a wifi network that you can log onto so you can set the inverter connection to the wifi router. However, even though the yellow led on the front was flashing, there was no network.
I used the front panel key to go to the "Set Protocol" option and held it to get to the wifi or RS485 option. I selected the RS485 - and then waited for it to timeout back to the top menu . And then did it again to set the protocol to wifi.
Using my phone I saw that the network "Solar-WiFi" appeared and so I tried to connect to it. After failing I found that the network had gone... trying over and over again, the network kept disappearing.
So I tried the "wifi reset" menu option.... same problem again.
After speaking with support - who were lovely, but, surprisingly enough, didn't get straight to the solution without a good deal of m'ing, a'ing and did you try this that and the other - I tried the "wifi reload" menu option and this did the trick. The network appeared and using the correct network password I connected and then using my browser I could open the inverters interface at 10.10.100.254 and follow the instructions to setup the link.
Some instructions I had said to use the "SolarMAN" app to help with the setup - I did try this when I was having problems but in the end I didn't use it so my advice is don't bother with it if you don't intend to use your phone/device to monitor the panels direct - least that's what I think SolarMAN is for.
BTW.. it's 16 degrees C outside with patchy sun and the house heating is off. However I'm sitting at my desk and my lovely solarboost device is pushing unused solar electricity into a 2.5kw heater in the room so i'm at a toasty 22 degrees for zero expendature (except the thousands initially invested in solar pv!).
Yay Solar Panels!... Yay SolarBoost!