Clean leaves, pollen, and dust off of your panels every few months to keep them operating at maximum capacity. Use a soft, long-handled brush to sweep dirt and debris away, using a ladder if necessary.
Remove stubborn stains using a garden hose and a mild detergent. Dish soap works well, or you can choose any biodegradable household cleaner. Apply the cleaner with your soft brush, then rinse the panels with the hose until all cleaner is removed.
Maintain the mounting brackets and supports. Clean these items regularly using a mild detergent and water. When you clean them, check that all connections are solid and tight.
Use a roof rake to remove snow from your panels. Snow that covers the panel cells will keep them from providing adequate power to your home. Roof rakes can be purchased at most home-improvement stores, and should be used carefully to avoid damaging the panels.
Consider installing a self-cleaning system. Several companies, including OCS, have simple cleaning systems that will maintain your panels for you. These systems can be hooked up to reclaimed water sources (like rain barrels) or right into your water lines. These systems are especially useful if your panels are on a high roof or in an inaccessible location.