This is a hot topic and I will try and simplify the issues in relation to residential solar. Let’s start with a little history. A few years ago in the mid -2000’s the dramatic increase in the use of computers snapped up the available supply of silicon. What little silicon remained on the worldwide market went into computer chips and was not available for silicon solar panels. In fact, silicon solar panels became very limited in supply. Thus, they became very, very expensive.
However, the new owners of First Solar saw this scenario unfolding years earlier. In fact, waiting in anticipation for this day to occur they had placed in storage a huge supply of their own type of solar panels which used Cadmium Telluride (CdTe) instead of silicon. You would expect this of the new owners since First Solar was owned at this time by none other than the Walton Family of Walmart fame and glory.
Simultaneously, the European appetite for solar ran unabated. At about 72 watts per panel, Cadmium Telluride (CdTe) solar panels reigned supreme and became the preferred choice of panel for the European Union. Hundreds of large utility-scale solar parks were installed in the European Union by developers who endured the mind-numbing permitting processes found in the EU. Regardless of price and cumbersome permitting these parks eventually covered hundreds of thousands of acres. Many of these parks were installed at well over $5.00 per watt while at the same time the manufacturing cost of a CdTe panel was under $1.00 per watt resulting in a generous profit margin for the panel manufacturer.
Several problems with CdTe panels began to grow with the main factor being the increased number of panels that it takes to match silicon panels in relation to the output of energy. Solar power produced by CdTe panels takes up far more space on precious roof-tops where space is limited. More panels mean more racking and more wiring. This limitation began to resonate both in Europe and the United States. Sales of CdTe solar panels began to slowdown.
Then in what seemed like the blink of an eye, the Chinese exploded on the worldwide scene with their own versions of solar panels made from the old stand-by, silicon. The Chinese plants were heavily subsidized by their government and prices of panels began to drop like a rock while the wattage contained in a single panel grew steadily.
Today we can find 400+ watt Chinese solar panels made from silicon that sell for under $1.00 per watt. And for the homeowner who is comfortable doing his/her own electrical this is where you may want to start in your search for a solar panel to fit your needs. However, the truth is that a significant number of the Chinese solar panels do not meet the wattage listed in their technical specifications. In addition, manufacturing defects limit the life of these panels. So for the DIY homeowner there is an interplay between your own risk tolerance, the price you can afford, and the quality of the panel that you wind up with by sheer chance. I suggest to DIY homeowners using this route to make sure that you buy at least 20% more panels than you need for your project so that you will have plenty of replacement panels.
But for the homeowner who wants more certainty, I recommend Kyocera panels from Japan. Kyocera is affordable but have the fabulous high quality standards that made Toyota famous. Kyocera has a plant in Mexico and they have been able to bring their prices into a delightfully affordable range. These panels are made from silicon and you should be able to find them for around $1.50 a watt or less.
Now you are asking about the many other variables that enter into the decision-making process regarding residential solar: efficiencies, amorphous silicon (a-Si), copper indium gallium selenide (CIS/CIGS), crystalline silicon, monocrystalline silicon, polycrystalline silicon. Gosh! This means that we are going to have a Part Two!