Updated: Jan 14, 2022
One common question from prospective homeowners and businesses is, "what is the difference between a standard efficiency solar panel and a high-efficiency solar panel?" While efficiency is a general difference, it is not the only difference. Inside, we discuss these differences.
What is a High-Efficiency Solar Panel?
A high-efficiency solar panel has a rating of greater than 20 percent efficiency. What that means is that the solar panel must collect and convert more than 20 percent of the incoming solar radiation that strikes its surface. A standard-efficiency panel collects and converts less than 20 percent of the incoming solar radiation that strikes its surface.
High-efficiency solar panels are generally more expensive than are standard efficiency solar panels. However, the sticker price can be deceiving. What the price tells us is the initial cost of the panels. What is not mentioned is the price per watt-hour of energy produced. High-efficiency solar panels convert more incoming solar radiation (sunshine) into usable energy. Potentially, that means you may need fewer panels, which can affect the total cost of the solar array.
Another aspect of price is the rate of degradation of the panel's efficiency. Over time solar panels lose efficiency, but the rate at which they do is not the same. Studies show that high-efficiency solar panels degrade slower . but degradation still occurs. So, while high-efficiency solar panels cost more initially, they may cost less over the life of the solar array. That is because they will produce more energy due to their slower rate of decline.
A big difference between the two is found in the warranty for parts and labor. Another important market trend is that high efficiency panels have a 25 year parts and labor warranty. Standard panels generally have a parts warranty for ten years.
A standard solar panel has an efficiency rating above 17-19 percent range. There are differences between brands so shopping around is helpful. Because high-efficiency solar panels are rated to capture 20 percent or more of the sunlight that strikes their surface, they produce more usable energy. Depending on the efficiency rating, that can mean as much as ten percent more power per panel. That additional energy production can grow as the degradation of the panel occurs - this being a comparison of standard panels vs. high-efficiency panels. Over the lifetime of the array, you will gain more energy from high-efficiency solar panels since they produce about 10 percent more energy over energy production with standard panels.
If you are looking into going solar, you will probably look at the cost of a solar array and its installation cost. Dig deeper and start to look at the costs of producing a watt of energy. Make a list of questions to ask solar companies and solar installers. That list can look like this:
• How much is the cost of the system and installation per watt of electricity it produces? The answer will help you see the value of the offer. The price per watt can range from $.2.20 per watt to over $3.30 per Watt. That's a big difference, and that cost is what you will pay for the energy the array produces.
• What is the degradation rate of the panels? That data should be available, and it will help you see how efficient the array will be year-over-year. If a panel degrades by one half of a percent per year, it loses 5 percent efficiency in ten years. Panels that degrade quicker cost you more because they produce less energy. That can be an opportunity to make a more informed decision about which type or brand of solar
panels you choose. It can also be a deciding factor between one solar company and the next.
• Are high-efficiency panels worth the extra cost? Answering this question is really about discovering the actual cost of the system - cost per watt of energy produced and the system's overall efficiency at years ten, fifteen, and year twenty. These answers show the value of the overall system and the ROI on your solar investment.
A big tip is understanding that solar installation and costs are not the same from one house to the next. Each property and home have solar advantages and challenges that are unique to that property. Those factors also include how energy usage occurs at your home and can go beyond just understanding how much energy you need. The best solution is to have a solar evaluation and one that can answer the questions we've posed here.
Sources and Additional Reading
 Photovoltaic Degradation Rates - An Analytical Review - U.S. Department of Energy