Long time ago i needed a function that creates random passwords that can be used when creating accounts, we have been using this for a long time, a few minutes ago Johan Arwidmark asked where the script is. The answer is, it is in one of the modules that I have on GitHub
Link to the module: https://github.com/DeploymentBunny/Functions/blob/master/VIAUtilityModule.psm1
You download it, import it an then you have a new command
New-VIARandomPassword -PasswordLength 15
New-VIARandomPassword -PasswordLength 15 -Complex $true
Very easy to use, you can select to do it standard or complex and if you need many of them just loop it.