Purchase a pre-cut rectangle of plexiglass. Place the rectangle on a work surface. Shake the can of black matt spray for five seconds. Spray the rectangle with the paint spray to alter the reflective qualities of the plexiglass so it will appear more like that of a solar panel. Let the paint dry for a day before continuing.
Look at a picture of a solar panel to see the kind of pattern that is typically on its surface. Draw a similar pattern on one side of the plexiglass using a model paint brush dipped in white paint. Let the paint dry for a day before continuing.
Go to the attic. Drill a hole between two rafters to one side of the peak in the ceiling with a portable drill. Measure 10 feet to the right of the first hole. Drill another hole. Place a stainless steel lag bolt through each of the holes. Apply silicone paste around each of the holes.
Go to the roof. Place the exposed end of each bolt through the bottom hole of a short mounting pole. Screw a nut onto the end of the bolt to secure it to the mount from the inside. Tighten the nut with a pliers. Place bonding glue around the mount where it meets the roof. Let the bonding glue set for 24 hours before continuing.
Place bonding glue on the top of the mounts. Place a metal rail that is the same length of the plexiglass on top of each mount, parallel to the other. Let the bonding glue set for a day before continuing.
Place the plexiglass, pattern side up, on top of the rails so that the left and right sides of the plexiglass line up with the rails. Screw metal screws through the plexiglass and into the holes in the rails on each side, two or three screws per side, using a power drill with a Phillips-head tip.