​The Sunshine Farm, in central Kansas, offers a unique data set detailing all the inputs and outputs of a farming project intended to be based, as much as possible, on solar energy. Such a complete and detailed data set, encompassing more than 1.25 M data points for an 85-ha, 7-year project, has never before been compiled for any farm. The data show that important energy inputs that have thus far been left out of existing farm energy efficiency estimates, with implications for biofuels and other biomass for energy technologies. The SSF achieved energy efficiencies superior to conventional agriculture while maintaining soil health and delivering more nutritious, organic products. A first-ever analysis of the energy efficiency of horse traction shows that horses are significantly less energy efficient and much less labor efficient than tractors, although the horses in the study were clearly underutilized. An analysis of the farm removing all inputs and outputs relevant to the horses shows that without horses the Sunshine Farm would have been competitive with conventional energy efficiencies even taking into account the farm's higher labor inputs and small size.