SolarHow Efficient Are Solar Panels

New Mexico’s state flag is the red sun of the Zia people, a symbol not only of our state’s rich cultural roots but also the relentless sun that is a part of everyday life in New Mexico, year round. The sun has a special place in the hearts of New Mexicans as it perfectly grows chiles in the earth and then later dries them in ristras hanging from every porch. The sun is as much a part of the New Mexican culture as yucca or the piñon pine.

So when it comes to solar power, there’s little wonder that New Mexico has invested so heavily into this technology. In a land where the sun shines nearly year round there is ample opportunity for solar panels to power homes and businesses. After all, it’s New Mexico’s uncommonly clear skies that make the state home to some of the most famous observatories such as Apache Pointe, the Very Large Array, and Magdalena Ridge. We’re a sunny state, and we embrace that.

So how efficient are solar panels in New Mexico? How well does the sun’s rays transform into electricity? Let’s find out.

What Affects Solar Panel Efficiency?

There are a lot of things that affect a solar panel’s efficiency—everything from weather to materials to wiring. Living in a great sunny state like New Mexico is going to help your energy efficiency better than living in cloudy Seattle, but what else makes solar panels more efficient? 

Well, let’s get the first question out of the way. What is the efficiency of a solar panel? The answer is somewhere between 15% to 22% of solar energy is converted into usable energy. This efficiency is often referred to as performance, and it is measured using the Standard Test Conditions test (STC).

Standard Test Conditions

The standard test conditions are a set of replicable conditions that determine the efficiency of a solar panel. They include the following:

  • Temperature of the cell: 25 degrees Celsius (approximately 77 degrees Fahrenheit)
  • Solar Irradiance: 1000 Watts per square meter (Wpm2) This is the amount of light falling on a given space at a given time.
  • Mass of air: 1.5. This number is a bit confusing, but has to do with the angle of the sun or, more specifically, how much air the sunlight has to pass through to hit the solar panels. A sun far on the horizon will have much more mass of air than sun directly overhead.

What all of this boils down to is the equivalent of a sunny day at 77 degrees with the sun on a 37 degree angle from the panels. Under these conditions, a solar panel with 15% efficiency hitting one square meter of panel would produce 150 Watts. 

Weather

In addition to testing the ideal conditions (which we recognize aren’t the typical conditions in New Mexico where average summer temperatures can range from 100 degrees in low areas to 78 degrees in high altitude areas. So in addition to using that standard test, they also check weather conditions.

Testing of Solar Panels Under Extreme Conditions

  • Snow: Not everywhere in New Mexico experiences a lot of snow—in fact, few places do have sustained snow falls regularly. Solar cells stop working when 5 cm of snow accumulates on the panel. Solar panel efficiency drops to 0%. Fortunately, in New Mexico we don’t have to deal with a lot of snow.
  • Wind: Wind doesn’t change a solar panel’s efficiency, but flying debris can damage a solar panel. Solar panels are tested for flying debris and are built to resist it.
  • Hail: To simulate hail, solar panel testing companies fire artificial hail at 20 to 30 meters per second. Under these conditions, solar panels remain undamaged.
  • Ice: Ice, like snow, can decrease efficiency if it gets too thick. Fortunately, solar panels with silicon coatings don’t have problems with ice buildup under normal conditions.
  • Damp heat testing: This is tested during highly humid conditions. In New Mexico, with the exception of a few weeks in late summer, we don’t have to worry about too much moisture.

Types of Panels

There are three primary types of solar panels on the market. (There are more, but these are the most common.) In order of most efficient to least efficient, they are:

Monocrystalline Solar Panels

Monocrystalline solar panels, also called single-crystalline cells, are made from the purest of silicon. This silicon is grown as a crystalline rod that is then cut into thin slices that will comprise the solar cells. They are the most efficient panels, with a solar panel efficiency coming in at between 19% and 22%. However, because they require pure silicon and are difficult to manufacture, they are the most expensive option.

Polycrystalline Solar Panels

Solar panels made of polycrystalline solar panels, also called multi crystalline cells, are not as efficient as monocrystalline cells. This is because the cells, as the name suggests, are grown not from a single silicon crystal, but from many smaller crystals. These smaller crystals are cut thin and make up an individual solar cell. Polycrystalline solar panels range in efficiency from 15% to 20%, and they make up the bulk of most solar panels on the market.

Wiring and Busing

One part of solar panel efficiency that often gets overlooked is the action wiring of the panels and the “busbars”. Busbars are metal bars that carry large amounts of current. Every home has busbars in it, made from aluminum or copper, that distribute power from the power source (solar panels in a solar home, or the electrical grid in a non-solar home) to the circuit breaker. The quality of the wiring and the busbars plays an integral role in the efficiency of the solar panel. Think of it like a water tower: there may be plenty of water in the tower for everyone, but if the pipes are leaky, or overly narrow, the water won’t come out at the rate you want it to.

Reflection

Finally, the reflection off a solar panel will contribute to the efficiency (or lack thereof). If a panel is highly reflective, the solar energy will bounce off of it and not be absorbed by the solar cells. This is why the glass layers on top of silicon cells are particularly important.

Conclusion

New Mexico’s climate makes it an ideal place for solar power. We have sunlight in spades, and very little weather that will interfere with the panels’ efficiency such as ice and snow. And when you combine the high efficiency of these solar panels (whichever type you choose) with the solar tax credits available for New Mexico residents, you can’t lose.

 

Are you ready to try solar panels on your home?

 

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