Here is another method which extends the value:
 Code:
$oXL = CreateObject("EXCEL.application")
$oXL.Visible = 1
$rc = $oXL.Workbooks.Add
$array = "Line1" , "Line2", "Line3"
 
For Each $sValue in $array
	$oXL.Cells(1, 1).Value = $oXL.Cells(1, 1).Value+IIF($oXL.Cells(1, 1).Value="","",Chr(10))+$sValue
Next