Good question - I'm certain that one of our community members will chime in with assistance.
In the meantime, I wanted to alert you to an RFP Template Hub we have available at Ariba Exchange. We invite community members to post templates that others can use. I couldn't find a template related to solar energy, but there may be other templates you'll find useful. And, if you do get a RFP template for solar energy we hope you'll add it to the hub.
Here's the link:
Ariba Exchange Community Manager