What kind of module mount: stationary or tracking?

PV modules (solar panels) can be mounted on structures that are stationary or track the sun. Stationary mounts may be seasonally adjustable so that they will tilt north or south to be perpendicular with the noon day sun. Trackers follow the sun keeping the plane of the modules perpendicular with the rays of the sun all day. The output of a solar array can be increased over 50% on a summer day on a tracker. On a yearly basis, depending on type of tracker and your geography, the PV output can range from 25% to 40% increase over stationary mounting.

Trackers are not cost-effective if the array is less than eight modules, unless they are part of a PV-direct water pumping system. Trackers are best if your energy demand is high in the summer months–refrigeration, water pumping, fans, etc. Also, your site needs to provide a low east-west horizon. If most of the early morning and late afternoon sun is blocked out by the terrain around your array, then a tracker is not good investment. A tracker will cost 2 to 3 times more than a quality stationary mount.

Stationary mounts can either be partially adjustable for seasonal angle of the sun or fixed in one angle for the whole year. The fixed angle is usually your latitude (36 degrees at Rocky Grove. Or plus or minus 15 degrees from your latitude if you want to favor the summer or winter months. Changing the season tilt angle four times a year will increase PV energy production by 5 to 7% over a fixed position. Usually roof mounted arrays are not adjustable due to the difficulty of access.