Solar Panel Efficiency

Solar Panel Efficiency and The Factors That Affect It


What’s a typical solar panel efficiency rating?

Most solar panels are around 11-15% efficient (check out this handy comparison table of solar panel efficiency to see the differences between brands). The efficiency rating measures what percentage of sunlight hitting a panel gets turned into electricity that you can use. The higher the efficiency, the less surface area you’ll need in your solar panels. Although the average percentage may sound a little low, you can easily outfit a typical roof with enough power to cover your energy needs.

What are the most efficient solar panels?

In the lab, scientists have developed solar panels that are 40% efficient, or even slightly more than that. But there’s a big difference between the lab and the real world. Manufacturers haven’t yet figured out how to take these experiments and produce economically viable products. Thinking you should wait for new whiz-bang panels is one of the most common solar myths.

Out of the solar panels on the market, SunPower makes some of the most efficient–one of their models is 19% efficient. They’ve reached that number by using several techniques, including a reflective coating that can capture more light from an angle. They also offer a line of panels that’s 18% efficient. Sanyo, another solar panel manufacturer, offers efficient models as well.

Should I choose the most efficient solar panels available?

High efficiency doesn’t mean better, it just means your panels use less space on your roof. Efficiency isn’t usually a critical concern unless you have an unusually small space for your solar panels. The most efficient solar panels cost a little more, so they’re a less common choice.

One Block Off the Grid’s pre-negotiated solar deals typically offer a choice of different recommended panels, including a more efficient panel for smaller spaces. If you have a normal amount of roof space to work with, you can focus more on the cost of the solar panels and the annual expected kilowatt production of your panels. We’ll help you choose the best panel for your particular needs and design a customized system around them. To request your free, no obligation system design and price quote, sign up here.

Getting the best power performance

In addition to efficiency and size, there are other factors that affect how much power your solar panels will generate. It’s important to make sure panels are installed in the optimal position, which is why you want to work with a highly experienced provider like One Block Off the Grid. The installers we work with will determine the correct orientation for your panels based on the direction and angle of your roof. They’ll also make sure the panels are installed with the proper amount of airflow so they stay cool– solar panels don’t like it too hot, and they’ll produce more power if they’re the right temperature. (To learn more, check out this article on how solar panels work.)

If you just go to the Big Box store and slap on a bunch of panels, you could end up wasting a lot of money. A high performing, long lasting solar array can incorporate dozens of factors in its design.

Factors that affect solar array efficiency include:

  • Panel Orientation

    In the U.S., your roof ideally should face south, but a quality design can often compensate for other directions.

  • Roof and Panel Pitch

    The “pitch” or tilt of your roof can affect the number of hours of sunlight you receive in an average day throughout the year. Large commercial systems have solar tracking systems that automatically follow the sun’s tilt through the day. These are expensive, however, and not typically used for residential solar installs.

  • Temperature

    Some panels like it hot but most don’t. So, panels typically need to be installed a few inches above the roof with enough air flow to cool them down. Some photovoltaic panels are designed to be more efficient in hotter climates. Check out the solar panels used by San Antonio and Phoenix home owners.

  • Shade

    Basically, shade is the enemy of solar power. With poor solar design, even a little shade on one panel can shut down energy production on all of your other panels (like a bad bulb in a string of Christmas lights). Before we design a system for your home, we’ll conduct a detailed shading analysis of your roof to reveal its patterns of shade and sunlight throughout the year. Then, our local installation partner conducts another detailed analysis to verify our findings.