If you know that you cannot reach your solar panels to clean them, the best thing to do would be to hire a professional to clean it for you. if you are not sure of who to call, you should ask the company that came and installed the panels for you.
Check into all of your potential rebates. You know there are rebates, correct? The government (in certain states) has a bunch of ways that they'll reward you for taking the solar energy plunge. And there are also benefits during tax season. Look into them all so you'll get every penny coming back to you.