SQL Server Sysadmin Audit Report Powershell script

Question: I need a powershell script which reports on SQL Server logins with Sysadmin privileges. My aim is to automate the process - so if you could provide a script which provides the sql server name , login and that I can schedule.

Answer:  This powershell script will execute across a list of servers - as defined in the file associated with the $instancepath variable.Create a text file and place 1 or more sql server instances in the file e.g 

server1\instance1

server2\instance1

$isodate=Get-Date -format s 
$isodate=$isodate -replace(":","")
$basepath=(Get-Location -PSProvider FileSystem).ProviderPath


$instancepath=$basepath + "\config\instances_all.txt"
$outputfile="\logs\sql_servers_sysadmin_report" + $isodate + ".html"
$outputfilefull = $basepath + $outputfile

$filePath = ""


#invoke stylesheet
$reportstyle=""




$dt = new-object "System.Data.DataTable"
foreach ($instance in get-content $instancepath)
{
$instance
$cn = new-object System.Data.SqlClient.SqlConnection "server=$instance;database=msdb;Integrated Security=sspi"
$cn.Open()
$sql = $cn.CreateCommand()
$sql.CommandText = "
SELECT 
@@servername,
mem.name [ID],
rol.[name] [Role]
FROM sys.server_role_members srm
INNER JOIN sys.server_principals rol ON rol.principal_id = srm.role_principal_id
INNER JOIN sys.server_principals mem ON mem.principal_id = srm.member_principal_id
WHERE rol.[name] = 'sysadmin'
GROUP BY mem.[name],rol.[name]
 "
    $rdr = $sql.ExecuteReader()
    $dt.Load($rdr)
    $cn.Close()
 
}

$dt | select * -ExcludeProperty RowError, RowState, HasErrors, Name, Table, ItemArray | ConvertTo-Html -head $reportstyle -body "SQL Servers sysadmin report"  | Set-Content $outputfilefull