Most people likely think that the hot and sunny San Antonio climate is optimal for generating solar power. While San Antonio is a great place for solar, the number of sunny days is the major reason. In fact, hot temperatures can actually lead to small reductions in solar panel energy production. In this article, we examine this effect and how to evaluate temperature coefficient.
Why Does Solar Panel Energy Production Decline in High Heat?
It’s normal to think that hot summer days are great for solar panel energy production. After all, we associate heat with the sun. While these days do generate good power, you might be surprised to learn that a sunny summer day in Minneapolis is likely a bit better for solar panel efficiency than a sunny summer day in San Antonio.
The reason for this ultimately comes down to the laws of thermodynamics. Solar panels generate energy in part through a flow of electrons inside their circuits. You may remember from science class that heat increases the activity of electrons. As they get hotter, they move a lot more. Inside your solar panel, this increased movement causes them to bounce around a little too much, reducing the voltage produced.
The good news is that this effect is not significant. You will still produce a lot of power on sunny summer days here in San Antonio. However, your solar panel energy production will decrease. Fortunately, there is a way to anticipate this effect, something known as the temperature coefficient.
What is the Temperature Coefficient?
If you’ve looked at the different solar panels on the market, you have probably noticed that they have a number of different metrics. One of these is the temperature coefficient, which is a way to evaluate the impact of heat on solar panel energy production.
Solar panels undergo a rigorous testing process. This testing typically occurs at a temperature of 25 degrees Celsius (77 degrees Fahrenheit). We mention Celsius because the temperature coefficient is calculated in Celsius, which is the standard in the majority of the world. The temperature coefficient essentially tells you the percentage of production lost for each one degree Celsius increase over 25 degrees.
How is Temperature Coefficient Calculated?
It is relatively easy to understand how the temperature coefficient is calculated. Let’s say that at 32 degrees Celsius (roughly 90 degrees Fahrenheit), solar panel energy production decreases by three percent.
Temperature coefficient measures the amount of solar panel energy production that is lost for every degree Celsius above the test temperature. Thus, the difference between 32 degrees and 25 degrees (the test temperature) is 7 degrees. Calculating temperature coefficient would mean dividing the three percent decline in production by 7. The result would be 0.43.
Thus, in this example, it is expected that for every increase of one degree Celsius, this solar panel would lose 0.43% of its maximum production. Thus, when evaluating solar panels, temperature coefficients closer to zero are optimal as they mean a solar panel’s energy production is less negatively impacted by heat.
How to Reduce the Impact of Heat
Of course, there are many things that can be done to reduce the impact of heat on solar panels. This typically involves finding ways to prevent the solar panel from absorbing as much heat on hot days. Many of these things can be done during the installation process.
For example, a common tactic involves mounting rooftop solar panels with a few inches of space between the panels and the roof. This provides for greater airflow which helps cool the panels, reducing their temperature and solar panel energy production loss. This is one of the reasons why finding a quality installer for your solar panels is so important.
Additionally, people in hot areas like San Antonio may opt for solar panels that are designed with lighter colored, reflective materials rather than panels that are black. This allows less heat to be absorbed since darker colors absorb more heat.
Finally, it is sometimes possible to install some of the electrical components of a solar system in a shaded area, which also helps to mitigate the impact of heat on solar panel efficiency. These are all small things that can be done to help enhance the performance of your solar panels.
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