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Your solar panels will be a significant investment, so it's perfectly understandable that you would want to protect them. Mother Nature can dish out the punishment: rain, wind, and hail threaten any outside structure. You might want to shield your solar panels with some sort of clear plastic screen. But will they still work if you do? Solar panels work through plastic reasonably well. Solar cells generate most of their power using visible light, so if you can see through the plastic, your panels will generate electricity. You will lose a little power, however, and the extra protection might not be all that valuable. The rest of this article will talk a little more about how solar panels work and also about their durability. Solar panels are designed to hold up under severe weather, and they are more rugged than they look at first glance. You can use clear plastic or glass to shield your solar panels without losing much power. But you might decide that it isn't all that necessary. The Solar Panel and the Spectrum The key to your solar panel is a unique combination of materials with special properties that combine to generate electrical current when exposed to bright light. Modern solar panels use two thin layers of semiconducting material. These two layers of semiconductors are where the power ultimately comes from. One material will have an excess of free electrons, while the other will have a shortage of electrons. On a molecular level there will be "holes" in the second layer that an electron can move into. Intense light will perturb the electrons so that they move from one layer into the "holes" of the second, creating an electrical current. The sun gives off light in many frequencies, corresponding to all the colors of the visible spectrum, and some frequencies that are beyond our ability to see: infrared and ultraviolet light. The typical solar panel can use light in all these frequencies. But visible light does most of the work of moving electrons around and generating current. A transparent material, such as glass or plastic, will absorb a minimal amount of light but let most of it pass through. So if you shield your solar panels with clear plastic, you won't lose a great deal of power. Solar Power and the Elements Your typical solar panel will come with a durable glass or plastic screen, so the parts that generate electricity are already shielded from the elements. Shielded pretty well, in fact. Solar Panels and Rain A well-designed solar panel will have the power-generating materials completely enclosed in water-repelling materials, minimizing their exposure to rain or humidity. Solar cells are almost always installed at an angle, usually sloping to the south, which allows them to catch more of the sun's rays. (They are turned to the north if you live in the Southern Hemisphere.) This slope also means that rainwater and snow slide off of them quickly. If your panels are installed correctly there should be no standing water that can seep into your solar panels and damage the key components. Solar Panels and Wind Strong winds can be a serious problem, especially if you live in the southern states with a history of hurricanes. You might worry about hurricane-force winds tearing your solar panels out of their moorings. But local building codes can be quite stringent, especially in areas that are prone to tropical storms. In southern Florida, for instance, building codes are based on solar panels remaining in place after being subjected to sustained winds of over 160 miles per hour. If you hire a reputable contractor who follows building codes, your solar panels should stay fixed in anything short of a category five storm without any additional wind protection. At that point the entire structure will be at risk. Two things are critical here. First, you want your panels fixed as firmly as possible. Your local building codes will provide standards for fasteners and connections; you want to be sure these are followed. Second, if you're worried about winds, you want as little space as possible between your roof and the panels. This prevents wind from going underneath your panels and creating "uplift" that can tear your panels off. If they are installed correctly, your solar panels can even serve to protect your roof structure. They should be as durable as any structure in your home. If you put up a plastic shield around your solar panels to protect them from the wind, that will create another obstruction that the wind will push against. In a strong enough storm, your shielding could be dislodged, damage your roof or solar panels, and add to overall debris. Solar Panels and Hail Hail is the last big weather threat, and it is one that can strike pretty much anywhere in the lower 48 states. But once again, solar panel makers are aware of the problem, and they have engineered panels that are up to the challenge. The outer shells of solar panels are designed to withstand one-inch hailstones falling at a speed of 50 miles an hour. Adam Savage of Mythbusters fame put his solar panels to the test and they fared pretty well, shaking off ice projectiles with hardly a scratch, though they didn't stand up as well to hard plastic or metal. In addition, because solar panels are installed on a slope, falling hail will usually strike a panel at an angle rather than head-on. This means even the largest hailstones will make a glancing hit that is less likely to damage the panel. If your solar panel setup allows you to adjust your panels to track the sun, you can use this to your advantage: whenever hail is in the forecast, move your panels to face the horizon. Doing this will make your solar panels into smaller "targets" and guarantee that any strikes will be at a wide angle. If You Still Want to Erect a Shield If all that doesn't reassure you, and you want an extra layer of protection, the best approach will be to use the same materials that solar panel manufacturers use for protective coatings; these will give you the best combination of light penetration and toughness. Most solar panels use tempered glass rather than plastic. Any additional shielding should probably follow this lead. Conclusion Solar panels mostly rely on visible light, rather than infrared or ultraviolet, to produce power. If you want to provide extra shielding for your solar panels, you don't have to worry much about losing power. Your solar cells will work through just about any clear, durable material. But you probably won't need the extra protection. Solar panels themselves are designed to shed water and fend off hail. And if they are correctly installed they should hold under all but the worst of hurricanes. Nothing is indestructible, but solar panels are pretty rugged.

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