If you’ve got a server with plenty of space you could run icloudpd: https://github.com/icloud-photos-downloader/icloud_photos_downloader
Apple
Here you can talk about Apple's ecosystem, Apple's OSs (Operating Systems), Apple's apps, Apple's everything!!
Thanks, do you happen to know if backing up to an external drive is also possible with this?
Sure, you’d just specify where to download to.
Move your photo library from ~/Pictures to an external storage volume with enough storage space. Then, either turn off iCloud Photo Library and allow the process to download all you photos or just export like you were doing to the external.
Why do you want to back them up? The iCloud sync is pretty good, unless you are worried about deleting photos yourself by accident and not noticing during the 30-day window that they would still be in the “recently deleted” directory.
Thanks! I’m backing up just in case. I try to do that with all my important data
If you end up copying the photo library file to an external volume, be sure to hold down “option” next time you launch photos.app—that will let you select the new location for the photo Library.
What are you trying to backup to? I’m assuming some 3rd party service? You might have to break it up by year or something and do it in batches.