How to Install an Exterior Solar Panel
Use these step-by-step instructions to wire and fully install a 1-kilowatt stand-alone system.
Use a Solar Pathfinder to determine if enough sunlight is available on the shed roof throughout the day. In this case, sufficient direct light reaches the solar panel between 11 a.m. and nightfall to provide the energy needed to operate typical workshop tools. Before wiring the solar panel, check the wiring diagram that comes with it for instructions specific to the unit.
Begin by connecting the wiring from the solar panel to the junction box. Add a watertight connector to the incoming end of the junction box and protect it from moisture. Strip the wires and insert the cable into the junction box. Connect the red wire to the positive connection and the black wire to the negative connection at the terminal posts. Use a screwdriver to tighten.
Attach the roof mounts supplied with the solar kit to the back of the solar panel. Bolt the support rails horizontally across the bottom of the unit (Image 1). Then bolt the support legs to the rails (Image 2).
With the mounting hardware in place, position the solar panel on the roof (Image 1). Temporarily attach the supplied support "feet" to the bottom of the legs and mark their mounting hole locations on the roof. After marking the holes, remove the feet. Drill holes (Image 2) for 2" screws. If the roof is plywood, add wood blocking inside to provide solid attachment for the screws. Apply butyl adhesive to the bottom of the detached mounting feet and use 2” screws to attach the feet to the roof. Position the panel and legs atop the feet and attach using the supplied hardware.
Route the wire from the solar panel across the roof, and position it under the overhang. Drill a 1/2” hole through the wall into the building interior just below this point. Pass the wire through the hole into the interior. Secure the wire with staples and seal the entry hole with silicone caulk.
Use 2" lag screws to secure the electrical utility box to the interior wall. The utility box houses the charge controller that manages the power between the solar panel, battery and load. It also houses the battery. Position the battery inside the utility box and insert the cable from the solar panel into the utility box. Use a watertight electric connector to seal the box from moisture.
Attach the wires to the terminal strip of the charge controller inside the utility box. Connect the red wire to the terminal marked positive and the black wire to the negative terminal. When the connection is completed and the power is on, a light on the controller will indicate when power is being generated by the solar panel (Image 1). Next, install the heavy-duty fuse (Image 2) inside the utility box. The fuse will act as an interrupt between the battery and the solar inverter.
Connect the battery to the fuse using heavy-duty No. 1 welding cable. Connect one end of the cable to the positive lug on the battery. Run another piece of welding cable from the fuse to the inverter and a third cable from the negative lug of the battery to the inverter. Run the wires from the terminal strip of the charge controller to the battery. Be sure to match the red wire to the positive terminal and the black wire to the negative terminal.
With the inverter turned off, connect two heavy-duty cables from the utility box to the back of the unit, which includes two receptacle outlets. Add a protective boot to prevent an electrical bridge from forming (which could cause a shock). Connect the positive and negative wires to the respective terminals, then turn on the inverter to check that power is flowing.
Attach the lighting fixture to the shed ceiling. Mount the electrical junction box that will house the timer switch near the door. Route 14-gauge wires from the fixture to the junction box. Clamp the wires to the box, strip about 3/4” from the black and white wires, and attach them to the timer switch as indicated on the label. Attach the bare ground wire to the green ground screw on the switch. Route 14-gauge wires from the charge controller to the overhead light fixture. At the controller, connect the red wire to the positive terminal, and the black wire to the negative terminal. At the fixture, connect the wires (black to black and white to white) to the wires from the timer switch. Secure these wire connections with wire nuts. Twist the bare ground wires together and attach them to the metal fixture. Before testing the lights and outlet power, double-check all connections.