Off-Grid Solar Installation

Prepare

1). Determine the area of the roof to install the PV array. The array refers to the solar panels that make up the system. Select a location that maximizes the sun's rays each day. Inspect the roof location to ensure the installation area has a sound and watertight surface before installing the photovoltaic array.
2). Calculate the size of your system, or how many solar panels, can produce the required power output. Add the kilowatt-hours (kWh) used each month. Divide the total kilowatt-hours by 12. The result equals the average kWh you use per month. According to the U.S. Energy Information Administration, the typical American household used 920 kWh per month in 2008. Residents in southern states tend to have higher kWh usage.
3). Divide your average monthly kWh usage by 30. This figure represents your average daily kWh consumption. Divide the average daily consumption by the number of hours for sunlight. The available daily sunlight depends on the season and region where you live. This figure determines the correct size, or total watts, for the solar panels.

1). Go to the attic to locate the roof rafter where you will start the installation. Use a hammer to drive a nail through the roof covering, along the side of the rafter, to help locate the rafter on the exterior side. Use your tape measurer to determine the distance between rafters -- usually 16 or 24 inches on center. "On center" refers to the center point of one rafter to the center point of the adjacent rafter.
2). Position PV rails or mounting brackets over the rafters. Mark the locations for the lag screw holes. Pre-drill holes in the rafters; this technique prevents splitting the wood when inserting lag screws. Secure the rail/bracket components with lag screws.
3). Use a trowel to apply high-grade sealant around the lag screw heads. The sealant keeps moisture from infiltrating under the roof covering and interior. Move the solar modules to the roof one at a time. Secure the solar panels to the brackets or rails according to the manufacturer's guidelines.

1). Follow the instructions for wiring the panels together to get the desired voltage and amperage power output. Choose between the series, parallel or combination wiring method, according to your needs. Consult with your electrician to determine the proper technique for meeting your electrical power needs.
2). Keep the wiring run as short as possible to minimize energy loss by the system. Most of the wire should run on the interior side of the roof. This makes for a neat, professional appearance. Attach the system wires to the charge controller. The charge controller provides a safeguard to ensure the system does not overcharge the batteries or drain the batteries too low.
3). Connect the system to the DC/AC inverter. The inverter converts direct current electricity to alternating current electricity, which powers normal appliances. Link the PV system to the building's electrical distribution panel.