what do you do during a solar decathlon when its overcast and rainy? i dont know, but 20 teams of college students do: they have designed and are currently building solar powered houses on the national mall between 10th and 14th streets. that's cornell's entry above. the competition began last friday and finishes this sunday the 18th. see what they are up to monday thru friday 11 a.m.-3 p.m.; Sat. & Sun., 10 a.m.-5 p.m. for some reason, the exhibit is closed Wed., Oct. 14.