Download Deployed Solutions (WSP) from Central Admin with PowerShell in SharePoint 2013

Using power shell run this below script.

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