The most practical tip for a homeowner installing solar here in the USA is to take an agnostic approach to solar panels. Great deals can be found when you become comfortable with the idea that your panel may not last as long as you were lead to believe when you read the manufacturer’s warranty.
I use this example as a teachable moment for solar: Do you remember at Christmas when most families placed strands of Christmas lights on their trees using the large multicolored bulbs as decoration? Those strands of lights were expensive! And then one year the bright white strands that were made in China broke into the US market. And families bought truckloads of them because they were so inexpensive. Now, not only do Christmas trees have lights but the entire house and yard is swimming in layers of strands of lights. When one strand breaks you simply
buy another strand because they are so inexpensive one doesn’t think of sending them back to the manufacturer for a replacement. My thinking is that this is rapidly becoming the attitude to take
In fact, a similar attitude is what the European Union has adopted and this is where I first heard the term “agnostic” used in relation to solar panels. Homeowners who use this approach should settle on a solar panel that has an element of interchangeability. And if you can tolerate a little more uncertainty, defective panels that do not meet the wattage requirements to carry a brand name may be the panel for you. Let me explain in relation to CdTe panels.
A CdTe panel is produced on a 250-foot long production line. Any speck of dust that adheres to the surface of the glass during the manufacturing process produces a “cool” spot and a corresponding reduction in wattage capability. At the end of the production line, the wattage on the panels are measured and the panels are sorted into wattage categories ranging from premium to basic and the manufacturer places his brand label on the panel. However, panels that do not make it to the basic level of wattage are called defective and cannot receive a brand label. They are then sold on the market as a very inexpensive “off-brand” with a limited warranty. These panels may be perfect for the brave DIY homeowner who wants to go completely off the grid for the least amount of investment.
The same idea works for silicon panels and they are used far more widely in the USA then CdTe panels. If you use silicon panels who will want to remember that silicon degrades over time in high heat and cannot tolerate a wide range of climatic conditions including freezing. In 2011, about 95% of all shipments by U.S. manufacturers to the residential sector were crystalline silicon solar panels. The silicon used in PV takes many forms. The main difference is the purity of the silicon, itself. Silicon purity is measured in terms of molecular alignment. The highest levels of alignment result in the production of greater levels of electricity. The processes used to enhance the purity of silicon are expensive. In fact, satellites in space are powered exclusively by silicon solar panels that have the absolute highest rates of efficiency and energy production. However, they are unaffordable for the average homeowner. Therefore, cost and space considerations need to be the driving factors for families unless you are launching a satellite.