IRVINE, CA (August 3, 2015): Join the growing number of volunteers signing on to assist with the U.S. Department of Energy Solar Decathlon, to be held at the Orange County Great Park on October 8-11 and October 15-18. Volunteers are needed to serve as docents, greeters, visitor liaisons, Education Day mentors and more. Some 64,000 guests visited the Great Park in 2013, the last year in which the competition was held, underscoring the need for a strong volunteer force to ensure a successful event.