Regardless of what type of solar panel you end up purchasing or is including in your system, it is important to understand the four major factors that will affect your solar system’s performance:
The biggest factor affecting the optimal performance of solar power system is how much sun it receives. Engineers call this variable solar insolation, which is simply a measure of the amount of sunlight that the solar cells receive. The more sunlight that the solar panels receives the better the solar system will operate, however, even if you live in a colder climate or a more northern geography, if your home receives plenty of sunlight, you are still a good candidate for solar power. (If you want to learn more about how solar panels work, you can click here.)
Please note that Germany, which is farther north than just about any state in the U.S., is the world leader in solar photovoltaic energy with over 9,000 Megawatts. That’s almost enough to cover the roofs of 2 million U.S. houses! So again, if you live in a colder or more northern climate, not too worry…as long as you receive plenty of sunshine you should still be able to go solar. To see how many hours of sunshine, on average, you can expect to get over the course of a year, check out the National Renewable Energy Lab’s online Solar Radiation Data calculator.
(2) Roof Slope and Solar Panel Orientation
Solar panels can be installed in a variety of different ways on a building, however, most people install their solar power system on their roof. Assuming your solar system is mounted on your roof, the next biggest variable in determining your solar systems effectiveness is the actual slope of your roof. Your roof slope will really help determine exactly how much sunlight your solar system receives. Furthermore, the proper roof slope will also depend on the latitude in which you live. For example, the closer to the equator you live, the flatter your roof should be as the sun is more directly overhead. The more pole centric you live, the steeper your roof should be as the sun is shining at more of an angle as opposed to overhead. And if you live in the United States, in general, solar energy installers will insist that your home receive plenty of sunshine from the south, due to the tilt of the Earth’s axis, so that your solar panels will receive maximum exposure. In the end, if you live in the U.S., have a solar system that faces to the south, and is mounted on a with a slope between 20 and 60 degrees, you should be in good shape to turn your home into a solar power home.
As a corollary to factor #1 above, if your solar panels are blocked by shade, they are not going to receive the proper amount of sunlight to operate effectively. So make sure that your roof is free from shading caused by trees, buildings or power poles. With trees, you can trim them or remove them to create the proper amount of sun exposure but if you have man-made structures blocking the sun on your roof, you may be in trouble.
Solar installers measure the shade coverage on your home in 30-minute increments. Also, as a rule of thumb, if more than 10% of any one of your panels is shaded then that panel may shut down the whole system temporarily because most panels are wired in series and connected to a single power inverter so the performance on one panel affects the others. Again, this shading may be mitigated somewhat if you can remove the blockage but sometimes this isn’t possible. As a result, many installers deal with this situation by customizing your solar power system such that the panels are either wired in parallel (where one panel will not affect the operation of the other) or such that each of the solar panels are connected to its own small individual power inverter. These techniques enable each solar panel to operate efficiently on its own without any adverse impact from shading on any of the other panels in the system.
(4) Dust and Dirt
Solar panels consist of a series of carefully manufactured, wafer thin photovoltaic cells which are very fragile. However, these cells are placed in and protected by a tempered glass case which is framed by non-corrosive aluminum. Because solar panels are exposed to the elements they are typically very sturdy and built to withstand rain, hail and other weather-related threats. In addition, the solar cells that make up the panel experience very little break down over time, similar to computer chips. As a result, most solar manufactures offer a full warranty over their solar panels for 20-25 years. However, the build of dust and dirt may impact the performance of your panels over time unless you are constantly cleaning them. Not to worry though as most solar manufacturers offer performance guarantees over 10-25 year period. Always make sure that the panels your solar energy installer uses come with a performance warranty.
Assuming you have quality solar panels, properly installed and oriented by a reputable solar panel installer, you should enjoy many years of ample electricity from your solar system. However, bear in mind, that since a solar power system is made up of electrical components, your system will experience electrical loss. For example, the wiring on your system will contribute to a certain amount of electricity loss which is due to the distance the electricity travels (among other things) and most solar installation professionals will try to minimize the total wiring length needed. In addition, you may also experience power loss as the DC current from the solar system’s panels passes through the power inverter and is converted to AC power. As a point of reference, good inverters are about 95% efficient. Finally, while plenty of direct sun is good for boosting total output, solar modules are not efficient at high temperatures.