A few functions that allow you to manage export of VMs for archiving.

Export-VMArchives.ps1

Function Remove-Checkpointsforexport{
    Param( [ValidateSet('All','RDP','SQL','DC')]
           $VMScope )
    BEGIN{}
    PROCESS{
        switch ($VMScope){
            ALL { $VMs = Get-VM }
            RDP { $VMs = Get-VM | Where-Object name -Match 'RDP' }
            SQL { $VMs = Get-VM | Where-Object name -Match 'SQL' }
            DC { $VMs = Get-VM | Where-Object name -Match 'DC' }
        }
    }
    END{
        $VMs | Get-VMSnapshot | Remove-VMSnapshot
    }
}

Function New-VmExportArchive{
    Param( $Path,
           $Archivepath )
    BEGIN{}
    PROCESS{
        if ((test-path $path) -ne $true){
            write-host -foregroundcolor yellow "$path does not exist."
        }
        else{
            7z a $archivepath $path
        }
    }
    END{
        7z t * $archivepath
    }
}

Function Get-VMExports{
    Param( [ValidateSet('All','RDP','SQL','DC')]
           $VMScope,
           [switch]$RemoveCheckpoint,
           $Path )
    BEGIN{
        switch($VMScope){
            ALL {$VMs = Get-VM}
            RDP { $VMs = Get-VM | Where-Object name -Match 'RDP' }
            SQL { $VMs = get-vm | where-object name -Match 'SQL' }
            DC { $VMs = get-vm | Where-Object name -Match 'DC' }
        } 
        if ($removecheckpoint -eq $true){
            remove-checkpointsforExport -vmscope $vmscope
        }
        $result = @()
        $i = 0
    }
    PROCESS{
        foreach ($v in $VMS){
            $vmexport = Export-VM -ComputerName $v -Path $Path
            $result += $vmexport
            $i++
            Write-Progress -Activity "Exporting $($v.name)..." ` -Status "$i of $($vms.count) Completed" `
                -PercentComplete "(($i / $($vms.count)) * 100)"
        }
    }
    END{
        new-vmexportarchive -path $path -archivename "$((get-date).datetime)Vm-Backup.7z"
        write-output $result
    }
}