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.

In 1954, Bell Labs pioneered the development of solar power technology, creating solar panels able to provide enough power to support the telephone service to a 1950s farming family. Approximately 56 years later, SunPower, in conjunction with Alcatel-Lucent and ConEdison Development, will install a 1.2 MW ground-mounted solar power system at Bell Labs’ global headquarters in Murray Hill, New Jersey.

Occupying six acres of the 200-acre Bell Labs campus, the SunPower system will generate approximately $2.5 million in cost savings over the next 15 years, which is the equivalent to the amount of energy required to power more than 200 average New Jersey homes on an annual basis.

At SunPower, our president and founder Dr. Richard Swanson has studied up on the early days of the solar industry and is excited about the implications of this installation. Swanson said “SunPower is proud to install this system at Bell Labs, the birthplace of many seminal technologies such as the transistor. Bell Labs is also the birthplace of the first practical solar cell in 1954. Now, 56 years later, solar cells have become one of the fastest growing sources of clean electrical power, so it is fitting that this national treasure is turning to solar cell technology for its power.”

Over the years we have found that while more and more people understand that solar energy is a great alternative to fossil fuels, many are still in the dark, so to speak, about solar cell efficiency.

In the following three part video blog series Dr. Richard Swanson, Founder, President and Chief Technical Officer of SunPower, shares some of his solar expertise and discusses the importance of solar panel efficiency. Dr. Swanson is a true solar energy pioneer who developed one of the first high efficiency photovoltaic solar cells to start SunPower 25 years ago.

In this first installment, Dr. Swanson explains solar cell efficiency and how higher efficiency solar panels benefit home owners. In clearing up the questions ‘what is solar cell efficiency and is there a limit to solar efficiency?,’ Dr. Swanson provides the following insight:

"Energy and sunlight are hitting your house in abundance. What we’re trying to do is to take the energy that is in the sunlight and convert it to electrical energy you can use to power your refrigerator and your lights, things like that" If you could turn all of the energy from the sunlight hitting your solar panels into electrical energy, the efficiency ratio would be 100 percent. But you can’t get that much out. The best efficiency you could ever get is 30 percent. SunPower is trying to improve the solar cell to reach that theoretical maximum efficiency of 30 percent. Where does the other 70 percent go? It turns into heat."

Additionally, Dr. Swanson explains how higher efficiency solar panels benefit home owners:

"After accounting for trees, pipes, etc. the typical house has a much smaller amount of useable roof area [for a solar system] than you might think. From that small region, you want to get enough energy to run your whole house " and that requires highly efficient solar cells."

We hope that the interview, filmed at SunPower’s very own Richmond, CA facility, will put you on the path to solar illumination. Let us know if you found this video helpful and what other solar panel efficiency questions you have!

Next week, Dr. Swanson will explain why solar panel efficiency is so important in calculating ROI and the total cost of a solar installation. If you crave some more solar discussion before then, join our community on Facebook at www.facebook.com/sunpower.

Enjoy!

For today’s installment of Solar Basics, we’re going to discuss the importance of system reliability. SunPower solar technology delivers the highest reliability in the industry, so our dealers and salespeople talk a lot about reliability with prospective customers. But for customers who are comparing many different manufacturers at many different price points, they want to know how to measure reliability and why it matters. Those are very fair questions. Here’s one video from SunPower dealer Independent Power Systems of Boulder, CO, which demonstrates one type of reliability:

SUNPOWER HAILSTORM VIDEO:

Solar system reliability is best summed up by three metrics:

1.    The functional lifetime of the panels - All dealers should share the functional lifetime of the panels. This is the number of years the panels are expected to produce power (as set by the manufacturer).

2.     How well the panels perform over their lifetime - Just like a computer processor or a rechargeable battery, solar panel production degrades over time. Some panels maintain higher levels of production over the course of their lifetime.

3.     Energy production continuity - Since solar panels need to face the sun, they are subject to the elements. Over a 25-year lifetime, the panels are exposed to a lot of rainstorms, hailstorms, snowstorms and even the occasional hurricane. All of these factors represent risks that could knock a panel offline. All panels differ on how well they can handle extreme weather and maintain consistent uptime. Be sure to ask your dealer for more details.

Reliability is important when you take into consideration the total cost of ownership over the lifetime of your panels. You are not receiving the full value of your investment whenever your panels aren’t functioning properly. A standard 25-year warranty may not cover you for everything. In addition, imagine having to go through the hassles of dealing with the company to replace the panels and the loss of energy production - and, what if this happened every two years or less? The losses can add up quickly…

To make sure you are investing in a reliable solar energy system, we’d recommend you to get answers to the following questions before you buy:

1.      How much experience does the company have installing and manufacturing solar panels?
2.      How extensively do they test their panels?
3.      What certifications do they have? Do they settle for the industry standard or go beyond it?
4.      How much of the design and manufacturing process does the company control

At SunPower, we take reliability very seriously. Check out this video detailing how we build and test our solar panels to provide the highest level of reliability in the industry:

In late January, SunPower CEO Tom Werner spoke on the ‘Economic Forecast 2011’ panel, an event organized by the San Jose Business Journal. Tom and fellow panelists, including San Jose Mayor Chuck Reed, Sobrato Organization Chairman John Sobrato and PriceWaterhouseCoopers Managing Director Rob Gittings, talked about the current state of their industries and provided their economic outlooks for 2011.

Among the morning’s comments, Tom described how 2010 is the first year of the Solar Decade. Solar is appearing everywhere, on commercial buildings and residential rooftops.

Tom talked about how SunPower is committed to halving the cost of solar over the next five years, making it a viable option for even more households and businesses. This cost reduction will make solar less dependent on incentives and will also allow owners to save more money on their monthly electricity bill.

See below for video of Tom’s comments. Also, check out Tom’s companion article from the San Jose Business Journal which describes the ‘Decade of Solar’ and SunPower’s growing investment in the Silicon Valley economy.

If you have any further questions or comments, please post them to our Facebook page.

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