Solar Energy
To extend the running time of a solar attic fan after dark, extra power is needed as well as a method to store that extra power during the day for use at night. The simplest method involves adding a second panel and storage battery. You can use a 12VDC fan system, but the format can be modified for 24VDC or above systems.
Instructions
1. Mount the fan system following the solar attic fan kit's mounting instructions. Be sure to leave room near the solar panel to mount a second solar panel.
2. Mount the second 12 VDC solar panel next to the attic fan solar panel, using the solar panel mounting kit and instructions.
3. Place the 12 VDC battery in a stable location near the attic fan motor. Note: the battery is heavy, do not place it between ceiling joists where only ceiling drywall is holding the weight.
4. Using pliers and utility knife, cut lengths of insulated wire to connect the positive (+) and negative (-) outputs of the second solar panel to the (+) and (-) terminals of the battery. Use the utility knife to strip insulation from the ends of the wire for the connections.
5. Use more wire (cut to length and the insulation stripped from the ends) to connect the battery terminals to the fan control inputs (+ to + and - to -). During the day, both solar panels will provide current to drive the fan and extra to charge the battery. After sundown, when the panels no longer provide current, the battery will begin a slow discharge, keeping the fan running until the battery has run out of charge. Depending on the solar panel output and the load represented by the fan, the fan may continue to run through the night.
Tags: solar panel, second solar, second solar panel, extra power, from ends