If you are thinking of adding solar energy to your home, garden, recreational vehicle, or even just for your camping and outdoor gear, you may be wondering about what they cost and how to install them. Of course, a major factor in the ease of installation, use, and energy efficiency is the weight of a solar panel. Today we'll explore how much a solar panel weighs, and how much weight it may take to get your energy needs met.
So Exactly How Much Do They Weigh?
Solar panels usually weigh 2-4 pounds per square foot. This weight load also needs to be distributed optimally on the roof; installers need to minimize the number of mounting locations in order to protect the integrity of the roof. This may mean that the weight per mounting location can be quite heavy.
How Many Solar Panels Do I Need?
Solar cells work in tandem, so that large solar panels not only generate more electricity overall, but they generate more electricity together than they would separately. A single installation of a 5x3 solar panel, for example, will generate more electricity than two panels half that size.
The typical solar panel is about 5 feet by 3 feet, and generates 320 watts of power per hour in peak conditions (full sun shining directly on the panel for that hour), or .32 kWh per hour. The amount of sunlight your solar panels will receive depends on where your home is located in the world, and the average amount of sunlight your home receives in a day. Assuming, for example, that you get 6 hours of direct sunlight on your solar panels in a day, you may be able to harvest 57.6 kWh per month from a single panel installation.
To determine how large a solar panel installation you may need, you can look at your current energy bills. Remember to average your needs over the year, as the amount of sunlight, and the amount of energy usage, varies over the course of the year. The average American home uses 897 kilowatt hours per month, averaged over the year. So if an average home got 6 hours of daylight per day, they would need 15 5x3 solar panels to meet their energy needs every month. 15 solar panels amounts to approximately 675 pounds in weight.
Is Your Roof Strong Enough For Solar Panels?
While 675 pounds sounds like a lot, they average out to 2-3 pounds per square foot, which is well within the weight tolerances of most roofs. However, there are a few things to consider in addition to the overall weight.
Is your roof in good condition?
If your roof is old, weak, or leaky, you should repair the roof before installing any solar panels. Not only will a new, solid roof be a better surface for your solar panels, but the presence of solar panels makes roof repairs more difficult and expensive. It is best to invest in any needed repairs first.
What about your rafters?
Solar panel assemblies should be attached through the roof to your rafters, not just to the roof itself. In some weather conditions, wind can get beneath the solar panels and cause an updraft. If the panels are not installed correctly, this uplift can be damaging to the panels and to the roof. Uplift should be prevented if possible.
What is the angle of your roof?
If your roof is at a very steep angle, it presents more challenges for solar panel installation. The angle of your roof may not be optimally angled to capture the direct rays of the sun. The panels themselves may often need stronger bracing and reinforcement racks to prevent any possibility that they will slide off of the angle of the roof. It may also need specialized equipment for the safety of the crew during installation.
Other Solar Panel Options to Consider
Solar cell technology improves every year, making solar panels more lightweight and more efficient. However, if you have concerns about the additional weight on your roof, there are some other solar options to consider.
High-efficiency solar panels
So far, we have been discussing the size, weight, and energy returns of typical solar panels. However, there are solar panels that are more efficient, generating more electricity with a smaller footprint. Generally speaking, high-efficiency solar panels are more expensive than traditional ones, but may be a good choice for your home.
Solar shingles are designed to look and work just like traditional roof shingles, but to provide electric power in the process. While they used to be much more expensive than solar panels, they are becoming more affordable, and are a great option if you need to repair your roof at the same time.
Other installation sites on your property
Some people have homes that are deeply shaded by trees, have a sub-optimal roof angle, or other factors that make their roof not a good choice for solar panel installation. But it is still possible to install solar panels elsewhere on the property, and simply use cables and lines to connect the electricity to the house. If you have a shady house, but a sunny spot on the lawn or elsewhere on the property, you could consider a free-standing solar panel installation that isn't on the roof at all.
Solar panels are designed to fit within the weight tolerances of most roofs, provided that the roof is in good condition, and weight is not typically a concern with a good installation. However, even if your roof is old, weak, or in a poor location for harvesting sunlight, there are still options for ways to add solar energy to your home, helping the planet, making you more energy independent, and saving you money on your energy bills every month. It's best to review your energy usage to help determine what you need, and then explore all the options to select the solar energy installation methods that make the most sense for your home.