I worked on one while it was in the early planning stages.
it's a good time, but be ready to be very frustrated with the rules & regs. The way the rules work, you have the best chance of winning building a small, super insulated house with the bare minimum of windows, and the biggest, most impractical solar array possible (look at colorado's two winners).
basically the rules in effect discourage things like practical innovation, which is precisely what competitions like this should be fostering.