Updated: Feb 28, 2021
It is often assumed that newer technologies will always surpass that of older ones. That's usually the case, considering updated technologies are meant to build upon the flaws and weaknesses of their predecessors. However, a critical thinker would typically prefer to research first before making conclusions based on broadly accepted concepts.
Having laid that out, let's pose the question we come across with regularly from homeowners. What's best? black panels or blue panels?
My answer to that is... it depends!
But before we go deeper into understanding the differences, let's go back in time to the roots of photovoltaic (PV) technology and walk our way forward to today's solar panels.
Solar Early Days
Solar has experienced a number of important technology breakthroughs since the first ever solar array was installed on a New York rooftop in 1884. American Inventor Charles Fritts was the first to produce such solar cells made from selenium wafers and an extremely thin layer of gold. Fritts' invention was based on the 1839 breakthrough discovery by French Scientist Edmond Becquerel, who's observations created the base upon which the entire solar industry today is built and defined—the “photovoltaic effect”. Selenium cells were very expensive to produce and thus this material is no longer used in the manufacturing process of modern PV systems.
The shift to more efficient, cheaper materials started when a Bell Labs semiconductor researcher by the name of Russell Shoemaker Ohl inadvertently made a p-n junction from pieces of silicon in 1940. However, the technology using silicon to make solar cells more affordable and efficient is credited to another team of Bell Labs' scientists in 1954.
While early Selenium cells could convert sunlight into electricity at 1-2 percent efficiency, the first ever silicon solar cell could convert sunlight at four percent and at a much lesser cost. Howbeit, commercialization was not initially a huge success as the first silicon solar cells were still expensive to produce. Yet, within a few years, solar cells started to become common to power satellites as well as other applications that followed.
We've made great strides since, as modern cells are four times more efficient now than what early Bell Labs cells were capable of in 1954. But, let me not get ahead of myself...
Types of Solar Panels
If you research different types of solar panels, you will come across thin film as the third major technology in the solar market, but for the sake of this article, we will only focus on the main two—monocrystalline and polycrystalline panels.
Most solar panels you will see have either a blue hue to them or they will appear black in color. The reason for this color difference is the interaction of light with the two different materials the panels are made of: monocrystalline and polycrystalline. Monocrystalline are black and polycrystallines tend to be blue. But, what's the benefit difference between black panels and blue panels? read on...
Monocrystalline cells are the latest technology of the two. It was developed with the purpose of improving the efficiency of solar panels, and increase it's reliability and life cycle. Monocrystalline panels range between 15-20% efficiency—a definite upgrade when compared to poly. The manufacturing process requires a higher level of material purity. The silicon is all oriented in the same direction in a single solar cell, creating one large silicon crystal—this process is known as the Czochralski process. Aligning the silicon into one single cell is energy-intensive and results in considerable wasted silicon, because the excess material needs to be cut off to fit the structure. As a result, monocrystalline panels are more expensive as they cost more to produce and add more waste and stress to the environment.
Blue panels are technically known as polycrystalline solar panels and the manufacturing process is consistent to the early silicon p-n junction Bell Labs discoveries of the 1940s. The panel derives its name "poly" because it is made up of lots of tiny silicon crystals allowed to cool and fuse together in a structure. Because the cells are made up of multiple crystals, randomly poured into the structure, these are not aligned uniformly, thereby decreasing the output of the cell compared to that of Black panels. Polycrystalline cells are typically between 13-16% efficient—slightly less than it's black counterpart.
Eficiency vs. Cost Benefits
Black panels typically generate more power than blue panels not just because of their higher efficiency but they also come in higher capacity modules. Most monocrystalline solar panels produce over 300 watts (W) of power capacity, some now even exceeding 400 W for commercial applications. Black solar panels are also space-savers as you typically require fewer modules than the blue ones to produce the same amount of energy.
Without a doubt, blue solar panels have their own array of benefits. It's true that polycrystalline panels, tend to have lower wattages due to its lower efficiency. However, poly-cells are less expensive to manufacture, thus have a lower cost; when space and sun exposure don't present production limitations, poly-cells would pose as a more affordable alternative; if you’re concerned about your ecological footprint, it might be something to consider that blue solar cells produce less waste in the manufacturing process and less energy in their production process.
Another difference to consider is how temperature affects the panel's peak power output (PPO). The way manufacturers calculate this phenomenon is through something called heat coefficient. As solar panel temperature escalates, its output current also ascends while the voltage production decreases linearly. Since power is equal to voltage times current, this translates into lower production in warmer climates. The power loss due to temperature is also dependent on the type of solar panel being used.
Mono-cells tend to have a higher heat coefficient than poly-cells giving black panels an edge over blue panels in hot weather. However, some may argue black panels absorb more heat than the reflective properties of the silicon fragments found in blue panels—thereby causing them to decrease their efficiency in hot climate (refer to individual manufacturer's spec sheet for model comparison on a case by case basis).
When it comes to physical appearance of the solar panels, to each his own—it all depends on each individual’s unique sense of aesthetics. But many users find that the cost benefit surpasses the less appealing look of the speckled blue hue of polycrystalline silicon. On the flip side however, cost not being an issue, homeowners may generally prefer monocrystalline solar panels as they find them more contemporary, aesthetically desirable and easier to the eye.
The short answer to this question is Monocrystalline cells will generally carry warranty of 25 year minimum, whereas Polycrystalline modules will have [up to] 25 year warranty. This is due to the average lifespan of each. Monocrystalline solar panel manufacturers will usually offer a 25-year warranty because of the proven durability of the material. Although on this constant of lifespan, poly-cells are not much different, the warranty period offered by the manufacturers may vary.
Aesthetics aside, when deciding which panels to use on a project you should always consider space, sun exposure, future needs, cost and life expectancy of the system. Whatever you choose should be consistent to the particularities of the project at hand according to the topics discussed previously.
MANOLO BARDEGUEZ - Welcome to my Blog. I hope the articles on this site inspire you and I encourage you to discover the benefits of going solar for yourself by clicking Go Solar. By clicking Join you can also learn how you can join our movement to connect the world to sustainable technologies and get paid handsomely by the fastest growing solar company in America. If you have any questions, you can contact me directly by email at ManoloBard@SunbrightNet.com or call me by clicking the phone icon above.