Upload all iOS photos to Flickr
Flickr gives you 1TB of free storage, which is bananas. Get an account, if you don't already have one and go to Settings > Privacy & Permissions and set the Defaults for New Uploads to View: Only you. Then this recipe will upload every photo that hits your iOS Camera Roll to Flickr as a private photo. This happens in the background. Then download the free IFTTT iOS app and set it to only upload photos over wifi to save your cellular data. Now your photos will be in iCloud and on Flickr. All of this is free.