Three types of solar heat collectors were evaluated for supplying part of the winter heating requirements of six different swine systems. Five methods of evaluation were performed: net present value, internal rate of return, payback period, percent heating cost savings, and percent purchased fuel savings. While most of the study assumed inflationary conditions a linear programming minimization model was used to select the system promising the greatest heat savings without inflation. It was found that generally the one-cover covered plate collectors were the most cost efficient. High capacity units tended toward more costly systems incorporating two-cover suspended plates and storage provisions. Solar energy proved to be a viable way to reduce purchased fuel and reduce heating costs...