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How We Choose the Best Solar Panels

Solar panels are the primary component of a solar power system and are comprised of solar cells which convert sunlight into direct current (DC) electricity via a process known as the photovoltaic effect (PV).

We have installed solar panels for homes and businesses throughout Southern California. We work only with the most reputable solar panel manufacturers, so the solar panel system that we design, build and install on your property will be guaranteed to produce the amount of energy that we say it will for the next 20 years or longer.

Our long track record of serving San Diego and the rest of Southern California since 2004 gives us the insight needed to know which solar panels to use and which to avoid, as not all solar panels are created equal.

Photo of robotic arm lifting solar panel in laboratory

Solar Panel Selection Factors

When determining what solar panels to use for our residential solar power installations, we adhere to a strict product selection criteria. Not just any solar panel can be included in a Sullivan Solar Panel system. We will only provide solar panels from manufacturers who are financially stable, have a proven track record, and are socially responsible.

Since we guarantee the performance of every system we sell for the first 10 years, we have a vested interest in making certain the solar panels we offer will perform as expected. The systems we install are designed and built to last over 25 years. With longevity and performance as fundamental criteria for selection, we will only deal with a handful of proven solar panel manufacturers.

Photo of someone checking checkboxes with a marker

Our Solar Panel checklist is fairly straightforward:

  • Illustration of a white colored checkbox with a white check Has the manufacturer been making solar panels for at least 25 years?
  • Illustration of a white colored checkbox with a white check Is the manufacturer financially stable?
  • Illustration of a white colored checkbox with a white check Does the manufacturer have a proven track record of producing quality products?
  • Illustration of a white colored checkbox with a white check Is the manufacturer socially responsible and aligned with the interests of the United States and our efforts to get the United States freed from imported fossil fuels?
  • Illustration of a white colored checkbox with a white check Does the manufacturer employ Americans or produce solar panels in North America?

Having been in the industry for as long as we have, we have watched as numerous solar manufacturers have come and gone. We are among the most established and reputable solar power companies and know how to maximize our customers' return on investment.

Black and white photo of a man and a child looking enthusiastically at a solar panel

The History of Solar Panel Technology

Solar panel technology is not new. Silicon-based solar modules were first used commercially by Bell Laboratories in the 1950 and solar power systems were originally used to bring small amounts of electricity to remote areas. Solar panels later were also used to fuel space exploration as the United States entered the space race in the 1960s. Interestingly, the original silicon-based solar modules had conversion efficiencies of as little as six percent. Today’s silicon-based solar panels have efficiencies as high as 25 percent.

In the past 60 years, solar power efficiencies have increased by an average rate of approximately 2.6 percent each decade. Silicon-solar modules have a theoretical maximum efficiency of 33 percent. As you can see, the belief that solar panels are going to be infinitely more efficient in the coming years is misguided, as the efficiency of today’s silicon solar modules is approaching its theoretical maximum.

Zoomed in photo of of monocrystalline and polycrystalline panels

Types of Solar Panels

The most expensive type of solar panels, monocrystalline solar panels are highly efficient in a variety of weather conditions and carry the longest lifespan. In fact, some monocrystalline solar panels installed in the 1950s are still functioning today.

Polycrystalline or multiple crystal solar panels

This type of solar panel does not function as well in shady areas, but they are more affordable and very efficient when placed in areas that receive lots of sunlight.

Cropped Image of SunPower, Panasonic and LG brand logos Image of SunPower, Panasonic and LG brand logos

We Use Only Quality Solar Panels

Panasonic Solar Panels

With over 40 years of research and development, Panasonic’s HIT Photovoltaic Modules offer industry leading warranties. Where many products only provide 10 years of warranty coverage, Panasonic offers 25 years on both product workmanship and performance. Their linear power output guarantee means that after 25 years, your panels will still be operating at 90.76% or higher.

Additionally, with the industry’s best temperature coefficient, Panasonic’s panels continue to operate at high levels despite of soaring external temperatures. This means the panels will provide your system with more energy throughout the day.

LG Solar Panels

LG Neon 2 modules, are one of the best values on the market. They provide near comparable high efficiency performance at affordable prices. Created using the most up-to-date technologically advanced processes available, they are recognized for their durability, convenient installation and aesthetic exterior. By conducting tests that exceed IEC standards, LG ensures that their modules satisfy the highest quality criteria upon leaving the production line. As a global, financially strong company, LG is a leader in the solar industry and will be a reliable partner for its customers for years to come.

Close up photo of solar array mounted to residential rooftop with view of palm tree and neighboring home in the background

Solar Panel Warranty Considerations

Product Warranty

Solar manufacturers typically provide a warranty for the product (the hardware) and a separate warranty for the rated power (the output) of the product. Solar panels are built to last longer than 25 years. The product warranty covers the components of a solar module which includes the solar cells, the aluminum frame, internal bypass diodes, the electrical junction box, and the tempered glass surface. A standard solar panel warranty is 10 years on the parts and 25 years on the output, adjusted for degradation.

Power Output Warranties

A power output warranty is based on how much power a panel produces over the life of the solar panel after taking into account solar cell degradation. As solar panels age, they can slowly degrade in efficiency, so solar power manufacturers often provide conservative ranges for power output to limit their exposure to warranty claims.

Cropped illustration displaying linear vs. standard output warranty protection Illustration displaying linear vs. standard output warranty protection

Linear vs Stepped Warranty Protection

Most manufacturers warrant that the solar panel will produce a given percentage of the original rated power. This typically is 90% of the nameplate rating for the first 10 years and 80 percent for the next 15 years. This standard type of power output warranty is known as a stepped warranty, which allows for aggressive solar cell and solar panel output degradation over time.

Allowing aggressive solar panel degradation is not aligned with the best interests of our customers, so we use only panels which have linear power output warranties. Our solar panel manufacturers warrant the panels they provide our customers will not degrade any faster than 0.7% per year.

When contrasting the two warranty types, note that a stepped warranty can have significant adverse financial impact on our customers, which does not align with our objective of turning every customer into a solar advocate.

Photo of solar array on top of house with warning sign superimposed in foreground

Solar Panel Output and Product Warranty

If a solar panel manufacturer provides a 10-year product warranty and a 25-year power output warranty, buyer beware! Let’s say a solar manufacturer warrants its solar panels will produce a given wattage for 25 years and also warrants the solar panel parts will last at least 10 years.

If the solar panel stops producing power in year 11, the output warranty will kick in and the panel will be replaced by the manufacturer, right? Not likely. If a bypass diode or other component in a solar panel fails in year 11, the manufacturer product warranty is what will determine the outcome.

In this case, the manufacturer would reject the claim and state the solar panel is out of its product warranty term, leaving the cost of the replacement of the solar panel to fall on the customer.

High contrast graph displaying production bell curve

Manufacturer vs. Solar Installation Company Production Warranties

A solar panel power output warranty is not the same as a solar energy production guarantee. Solar panels are rated in watts, which is a measure of instantaneous power. Solar energy is measured in kilowatt-hours, which is a measure of power delivered over a period of time

A solar manufacturer warranty provides some level of protection that a solar panel will output a given wattage when it is exposed to light under standard testing conditions. This does not mean that the solar panel will produce a given amount of energy over time, or kilowatt-hours when it is installed in the real world.

Solar manufacturers warrant that their panels will produce power, but they don’t guarantee that the contractor who installs them knows what they are doing and that the system, comprised of their solar panels, will produce the energy that is promised by a solar installation company, if any.

Illustration of parts of a solar panel working together to form a solar module

How do Solar Panels Work?

Solar panels are made of solar cells, which are a silicon semiconductor sandwich with a positive and negative charged layer. When photons in sunlight hit the cell, a direct current is created driving electrons from the negative charged silicon (n-type) to the positive charged side of the “sandwich.” This direct current leaves the individual cell and combines with the current from the other cells in a circuit contained within the solar panel. Typically, there are three solar circuits in a solar module comprised of 20 cells a piece, or 60 cells total (sometimes there are 80 cells in larger solar panels).

A typical solar power system is comprised of 12 to 30 solar panels for a home and from 30 to hundreds of panels for a business or other large commercial installation. Multiple solar panels connected together are known as a solar array, which can be connected to one or more inverters so the inverters can be electrically connected to the public energy grid. Learn more about how solar power works.

Photo of solar panel partially covered by shade

Solar Panels and Shade - Not a Good Pair

Shade cast on a solar cell makes the solar cell shut down. That’s why it’s call solar power, not shade power! In a solar power circuit, a shaded solar cell acts like a resistor and current cannot flow through it effectively. Shaded solar cells get hot when they are shaded and act like a resistor.

Therefore, bypass diodes are incorporated into the solar module so that if a portion of the module is shaded, the shaded circuit will be bypassed. Each circuit of 20 cells has a bypass diode connected to the circuit. The bypass diode provides a bypass circuit for solar current if any of the three circuits encounter shading.

There is one bypass diode for each circuit for a total of three. This means if one solar cell of a 20-cell circuit gets shaded, the entire 20-cell circuit gets bypassed. In a 60-cell solar panel, this means one-third of the rated output gets lost if only a portion of one cell gets shaded.

Photo of solar expansive solar arrays with healthy modules next to destroyed modules

Do Bypass Diodes Fail? If so what happens?

A bypass diode serves two important functions in a solar panel. It mitigates the impact of shade on production and keeps shaded cells from heating up. When a solar cell is shaded, it becomes a resistor and if the bypass diode does not function, the solar module will push current through the cell causing it to heat up.

As we have seen in numerous tests, a heated cell can crack the glass surface of a solar panel and can burn a hole through the back encapsulation of the panel. This can result in a fire hazard.

This is why it is imperative that solar power installations are done utilizing best practices as outlined by the North American Board of Certified Energy Practitioners (NABCEP). Improperly designed and installed solar power systems pose a hazard to persons and property. Properly designed and installed solar power systems subjected to a rigorous quality assurance and quality control program are inherently safer.

Solar cells subjected to shading before 9 am and after 3 pm will not generate the heat that could result in damage to the solar power system or its supporting structure (your home or business), in the unlikely event a bypass diode fails.

Cropped image of circle with line indicating no microinverters Image of circle with line indicating no microinverters

Do Microinverters Solve the Shade Issue?

No, and here is why Sullivan Solar Power does not offer microinverters or AC modules as a standard offering. We’re not like other companies, who offer microinverters and AC solar modules as a means to bypass the entire conversation about the true impact of shade on a solar power system and the long term detriment shade impact has on system longevity and safety.

Microinverters do not mitigate the hazards of shade because those hazards occur at the cell level and microinverters are attached downstream from the cells. The only benefit of a microinverter is that it will limit the impact a shaded module has on performance of the overall system.

It will not limit the damage a shaded solar cell will wreak on a solar panel if the cell is shaded during peak sun hours between 9 am and 3 pm.

Photo of roof mounted solar array elevated above trees with expansive view

Properly Designed and Installed Solar Panels by Sullivan Solar Power

Whether you want solar panels installed in San Diego, Orange County, or Riverside, Sullivan Solar Power has a team of highly qualified NABCEP certified experts nearby to help. We will use best practices to ensure your solar panels are installed correctly and will produce the most amount of solar energy possible given your site specifics.

Contact us today and we will provide a wealth of knowledge for your use in helping you decide how to declare energy independence.

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