Hi Jeff,
Thanks for your feedback.
We apologize for the confusion. While the diagram provides a 48V connection, each solar panel is rated at 12v. At the same time, it will also be up to your liking whether to connect them all in parallel to go with a 12V or parallel-series connection to end up with 24V, 36V, or 48V.
Please feel free to submit a ticket directly to us here should you have further questions: https://www.renogy.com/contact-us/. Or you may call us at (909) 287-7111 Monday through Friday 8:30am - 5:00pm PST. Please also have a multi-meter ready, this will help us troubleshoot faster. We hope to hear from you soon. Best, Renogy customer support