STEM education has expanded from classroom settings to informal or afterschool programs to incorporate more resources that can further facilitate and enhance the learning process. A growing number of informal learning programs include a variety of STEM subjects, including energy science. This study describes and evaluates a week-long immersive summer program in energy science and engineering that highlights the learning process and interactions between teachers and students as co-learners. The program incorporates lectures, field trips, hands-on activities, research projects, and the development of lesson plans. We used surveys and open-ended questionnaires to measure participant reactions and gain participant feedback on the program activities. Participants indicated a preference for the hands-on activities and field trips. Teachers expressed appreciation for the knowledge gained in energy science, while students particularly valued their social interactions with teachers during the program. Future programs could be improved through changes to lecture length, frequency, and delivery. Challenges include maintaining resources and stewardship.