How to get your pictures out of Facebook and into Google Photos
Facebook isn't a good long-term photo storage solution, and they make it hard to get your photos out, once they are in. Fortunately +Andrew Martonik
has written up step-by-step instructions on how to get your photos out of Facebook (including the limitations), and then how to get them in to +Google Photos
The short version of how to get your photos out of Facebook:
1. Go into your Facebook account settings on the web, and select "Download a copy of your Facebook data."
2. Wait for the Facebook email with a link to your data, and download the .zip file
3. Unzip the file on your computer, and isolate the "Photos" folder inside
4. (Optional) Don't use Facebook as a backup of photos you intend to download later
The images will be lower resolution than your originals, and will be missing the EXIF data (date, time, location).
Read the detailed instructions at +Android Police
on how to then upload those images to Google Photos: http://www.androidcentral.com/how-get-your-pictures-out-facebook-and-google-photos