The solar panels (also known as photovoltaic panels or photovoltaic modules) are the most obvious and most visible component of your solar energy system. They are also the part of the system that has the most options to consider. When you are choosing solar panels for your system, there are a number of factors that will go into your decision. These factors are similar to those of other buying decisions you make, and they also are inter-related.
The type of solar module you choose is based on what you will be using it for. For homes and other stationary uses, the type of module will be different than the type that is best suited for portable uses such as boating or camping.
A solar panel is made up of a grid of solar cells, and there are different types of solar cells to consider. Monocrystalline silicon solar panels are the most efficient at converting solar energy to electricity, but they are also the most expensive. Polycrystalline silicon panels are slightly less efficient, but they tend to be cheaper since they are cheaper to produce. Thin film solar panels are the least efficient, but they are also the cheapest and they are uniquely versatile since the film is so thin and flexible.
You might also want to look at solar shingles, profiled on our page on building integrated photovoltaics.
Again, this has a lot to do with the materials. As you would read on our solar cells page, different types of solar panels have different durability. Solar cells actually become less efficient with use, and will eventually wear out on their own. Before purchasing a solar system, be sure to ask about the life expectancy of the solar panels.
The best solar panels should be warrantied for 20-25 years, but your initial outlay will be much more. A cheaper system might only last for 10 years. This is a matter of personal choice, and how much you have to invest right now versus how soon you are willing to replace your solar panels. Just make sure that the panels are priced so that they will pay for themselves in energy cost savings before the warranty runs out.
Frames also make a difference in durability of your solar panels. Today, most PV panels are framed in aluminum, which is sturdy and light.
The size of the panel generally determines the wattage it will put out at maximum. A 50 watt panel (i.e., a panel that can produce 50 Watts per hour under ideal conditions) will be about two square feet, while a 190 watt panel will be about eight. The wattage is also determined by the kind of solar cells used, whether they are single crystal, polycrystalline or thin film. Since thin film is the least efficient technology, you'd need a much bigger thin film solar panel to produce the same amount of energy.
The size of the solar panel(s) you install will depend upon what your energy needs are, and how much physical space you have.
The actual cost will be determined primarily by size and type of solar panels you purchase. When comparing solar panel prices, you'll find that they are generally priced in dollars per Watt. This allows you to compare prices on an even footing across different sizes and materials, to truly understand what the best deal is.