A discussion of our Vernon Hills solar homes is well suited to the purpose of this control symposium. It is timely since we have been able to observe operations through the 1976-77 heating season and, as a consequence, the controls have beem modified for the 1977-78 season.

The initiation of a plan for modification made it necessary to consider the objectives of control systems -- however they might be constrained by cost or existing physical considerations.

The obvious and general objectives of a solar system are the maximization of solar harvest, optimum utilization of the harvested energy, a minimum of fossil energy consumption, avoidance of system losses and reasonable space comfort. The systeming and component dependent objectives are: (1) the optimization of beam radiation; (2) avoidness of freeze or stagnation; (3) provisions for excess heat storage or rejection; (4) power failure system protection; (5) control to enhance the use of low energy levels; (6) maximum reduction of utility energy inputs; (7) automation; and (8) simplicity, reliability and maintainability.