This article is in the individual Projects section of OpenSolar. Once you've navigated to the Projects page, click the specific project you would like to edit. Next, click into the Design section.
OpenSolar also allows you to upload your own imagery to use for designing systems. To upload an image, simply drag and drop the image onto the map in Studio mode. If you get an error, please ensure that the image file size is no greater than 1 MB. You will need to rotate the image outside of OpenSolar to face north before uploading it.