Solar Basics: Why Efficiency Matters?

For this week’s entry in the Solar Basics series, we’re revisiting the topic of efficiency. Everyone spanning installers, manufacturers, online commenters and industry experts will stress that efficiency is one of the most important drivers in the solar purchase process. But few resources provide a clear explanation of what efficiency is, how efficiency is calculated and what factors influence efficiency. Today we’ll try and clear up the confusion.

For starters, here’s an informative interview with SunPower Founder and President Emeritus Dick Swanson in which he explains solar panel efficiency and how it benefits homeowners:

Dr. Swanson touches on two key areas that influence the efficiency of solar power systems. First is the rate at which the solar panels convert the energy in sunlight into energy that will power your home. This is basic efficiency. To use a concept that most consumers are familiar with, it’s analogous to fuel efficiency in a vehicle, or that rate at which fuel converts into miles traveled. Just like with a car, a solar panel with high efficiency levels is more favorable (although sunlight is free while gas prices are volatile!).

Second are the barriers to efficiency that residents experience due to the physical location and setup of their homes. Key among these barriers is usable roof space. Certain roof areas might be unsuitable for solar panels due to their size, the direction they face and the ability of the roof to support panels. Sources of shade, especially trees, can also affect usable roof space.

When homeowners compute all these factors, they’re left with a specific tract of their roof that is suitable for solar. In many cases, homeowners want even fewer panels than possible due to cost or aesthetic reasons.  In making the solar purchase decision, it’s in the best interest of any owner to ensure that they can deliver the most energy per square foot of solar panels installed. For space-constrained owners, this ensures they can achieve maximum output. For owners worried about aesthetics, they can generate the same amount of power in a smaller amount of space. Taking into account reliability factors from our last Solar Basics post, highly-efficient and reliable solar power systems allow homeowners to generate the most electricity over the lifetime of their system.

At SunPower, we aim for transparency. On our website, you can find listings of our residential panel offerings and how their efficiency levels stack up against the competition.  Here’s a video detailing how SunPower’s solar power systems are the most efficient in the world:

If you have any additional questions about solar panel efficiency or the efficiency of SunPower products, please post them to our Facebook page or leave them below.