[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint")

function Get-ScriptDirectory 
{ 
  $Invocation = (Get-Variable MyInvocation -Scope 1).Value 
  Split-Path $Invocation.MyCommand.Path 
} 

$farm = [Microsoft.SharePoint.Administration.SPFarm]::Local

foreach ($solution in $farm.Solutions)
{
  $solution.Name
  $location = Join-Path (Get-ScriptDirectory) "Solutions"
  $location = Join-Path $location $solution.Name
  $solution.SolutionFile.SaveAs($location);
}