Solar Panel Efficiency and Power Ratings: What Does It All Mean?

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So you’ve decided that solar energy is a smart move for your household. Now comes the tricky part of shopping for and researching the different solar energy systems on the market.

It helps to have a specific goal in mind when shopping for solar. In this case, your goal in purchasing a solar system is to maximize production output, minimizing the cost of installation and overall electricity savings month-over-month and year-after-year. In order to do this, you’ll need to understand how two main factors work together to determine how much energy your system will produce: Power Ratings and Efficiency Ratings.

Power Ratings

The power rating is just that: a measurement of how much power your solar panels will generate out of the box. You might also see it referred to as “minimum warranted power” or “negative tolerance rating.” Panels with a higher minimum warranted power and a lower negative tolerance rating will produce the most energy.

It gets even more confusing when you realize there are two different standards for evaluating the power of your solar panels: STC and PTC. In most cases, you’ll want to look at the PTC rating to gauge how your panels will perform in real world conditions. PTC ratings will also be used to calculate your rebate - so you’ll want to look more closely at this number than the STC rating. STC represents Standard Test Conditions (lab rating) while PTC represents more of the real-world ratings (weather, etc.).

Efficiency Ratings

Power rating isn’t everything, though. You’ll also want to look at how efficient your panels are. Efficiency ratings tell you how much power your system will produce per square inch. This means that higher efficiency panels will produce the same amount of energy as lower efficiency panels, but will take up less space - thus lowering your cost of installation.

When comparing the efficiency of different solar panels, know that the most efficient solar panels on the market today have PTC ratings as high as 22.5% while the industry average is closer to 16 - 18%.

Be careful, though. Not every home requires the highest quality, most efficient solar panels on available and spending too much on equipment is counterproductive to your goal of saving money with solar energy.

The general “rule of thumb” is that if you have limited roof space, you should always select the highest efficiency ratings.

Understanding Your Home’s Energy Needs

Homeowners should research and understand their home’s energy needs before deciding how much production they want to get of their new system.

As you shop around and talk to different installers, make sure to ask as many questions as you want. A good company will provide you with the information you need to make an educated purchase. They will also work with you to understand your home’s needs and recommend a system that is right for you.

At Solar Optimum, we go beyond exceptional service by offering real, honest talk about eliminating or reducing your electric bill. From the moment you contact us with your solar needs, we consider you a top priority and a potential lifelong customer.

Whether you simply have questions regarding where to start, or you've done your solar-energy research and recognize that we're the people who can turn your goals into reality — the Solar Optimum team is here to serve you.

Download our free guide to learn more about purchasing your first solar energy system for your home!

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