Simple Shade Sail actually, no moving parts, no batteries, and easy to install w/eye-bolts and small turn-buckles (adjustable, screw-type, stainless).  Initially, installed w/bungee cords to see the fit between wooden beams w/out drilling into new wood.  Once happy w/fit, inserted those eye-bolts and attached turn-buckles to eye-bolt and shade corner, and adjust for tightness at each corner.