PowerShell Command for getting the backup of WSP

PowerShell Command for getting the backup of WSP 

$FolderPath = "z:\Solutions\12July2016"
foreach ($solution in Get-SPSolution)
{
   $id = $Solution.SolutionID
   $title = $Solution.Name
   $filename = $Solution.SolutionFile.Name
   $solution.SolutionFile.SaveAs("$FolderPath\$filename")
}