SharePoint Online: Get Site Collection Storage Size – Quota Usage Report using PowerShell

#Config Parameters
$AdminSiteURL="https://crescent-admin.sharepoint.com"
$SiteURL="https://crescent.sharepoint.com/sites/Ops"

#Get Credentials to connect to SharePoint Admin Center
$Cred = Get-Credential

#Connect to SharePoint Online Admin Center
Connect-SPOService -Url $AdminSiteURL -Credential $Cred

#Get the Site collection
$Site = Get-SPOSite $SiteURL

#powershell to get sharepoint online site size
Write-Host "Allocated:"$Site.StorageQuota
Write-Host "Used:"$Site.StorageUsageCurrent
Write-Host "Warning Level:"$Site.StorageQuotaWarningLevel

#Config Parameters
$AdminSiteURL="https://crescent-admin.sharepoint.com"
$ReportOutput="C:\Temp\SPOStorage.csv"

#Get Credentials to connect to SharePoint Admin Center
$Cred = Get-Credential

#Connect to SharePoint Online Admin Center
Connect-SPOService -Url $AdminSiteURL -Credential $Cred

#Get all Site collections
$SiteCollections = Get-SPOSite -Limit All
Write-Host "Total Number of Site collections Found:"$SiteCollections.count -f Yellow

#Array to store Result
$ResultSet = @()

Foreach($Site in $SiteCollections)
{
    Write-Host "Processing Site Collection :"$Site.URL -f Yellow
    #Send the Result to CSV 
    $Result = new-object PSObject
    $Result| add-member -membertype NoteProperty -name "SiteURL" -Value $Site.URL
    $Result | add-member -membertype NoteProperty -name "Allocated" -Value $Site.StorageQuota
    $Result | add-member -membertype NoteProperty -name "Used" -Value $Site.StorageUsageCurrent
    $Result | add-member -membertype NoteProperty -name "Warning Level" -Value  $site.StorageQuotaWarningLevel
    $ResultSet += $Result
}

#Export Result to csv file
$ResultSet |  Export-Csv $ReportOutput -notypeinformation

Write-Host "Site Quota Report Generated Successfully!" -f Green

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

$SiteURL="https://crescent.sharepoint.com"

#Get Credentials to connect
$Cred= Get-Credential
$Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)

#Setup the context
$Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
$Ctx.Credentials = $Credentials
$Site = $Ctx.Site
$Ctx.Load($Site)

#Get Storage Details
$Site.Retrieve("Usage")
$Ctx.ExecuteQuery()
$Site.Usage.Storage

#Set Variables
$SiteURL = "https://crescent.sharepoint.com"

#Connect to PnP Online
Connect-PnPOnline -Url $SiteURL -Credentials (Get-Credential)

#Get the Site collection Storage Metrics
Get-PnPTenantSite -Url $SiteURL | Select @{Label="Allocated (GB)";Expression={$_.StorageMaximumLevel/1MB}}, @{Label="Used (MB)";Expression={$_.StorageUsage}},@{Label="Warning Level (GB)";Expression={$_.StorageWarningLevel/1MB}}

#Parameters
$AdminCenterURL = "https://crescent-admin.sharepoint.com"
$CSVPath = "C:\Temp\SiteUsageRpt.csv"

Try {
    #Connect to Admin Center   
    Connect-PnPOnline -Url $AdminCenterURL -Interactive
 
    #Get all site usage details
    $Sites = Get-PnPTenantSite  -Detailed | Select *

    $SiteUsageData = @()
    ForEach ($Site in $Sites)
    {
        #Collect site data
        $SiteUsageData += New-Object PSObject -Property ([ordered]@{               
                'Title'                    = $Site.Title
                'URL'                      = $Site.Url
                'Description'              = $Site.Description                    
                'Owner'                    = $Site.OwnerName
                'Storage Quota'            = $Site.StorageQuota
                'Storage MaximumLevel'     = $Site.StorageMaximumLevel 
                'Storage Usage Current'    = $Site.StorageUsageCurrent
                'Resource Quota'           = $Site.ResourceQuota
                'Resource Quota Warning'   = $Site.ResourceQuotaWarningLevel
                'Resource Usage Average'   = $Site.ResourceUsageAverage
                'Resource Usage Current'   = $Site.ResourceUsageCurrent
                'Template'                 = $Site.Template
                'Sharing Capability'       = $Site.SharingCapability
                'Lock Status'              = $Site.LockState
                'Last Modified Date'       = $Site.LastContentModifiedDate
                'Subsites Count'           = $Site.WebsCount
            })
    }
    $SiteUsageData
    #Export Site Usage Data to CSV
    $SiteUsageData | Export-Csv $CSVPath -NoTypeInformation
    Write-Host "Site Usage Report Generated Successfully!" -ForegroundColor Green
}
Catch {
    Write-Host -ForegroundColor Red "Error generating site usage report:" $_.Exception.Message
}