There are many factors you’ll want to take into account when choosing a solar (PV) system for your home. In this chapter, I will provide the basic information about the different types of solar panels for home use (monocrystalline, polycrystalline, and thin-film).
PV cells are fabricated using semiconductors as light-absorbing layers that convert the energy of photons into electricity without causing any noise or air pollution. When photons enter the cell through a transparent contact, they’re absorbed by the semiconductor, thus creating electron-hole pairs. A special layer called a “junction” in the body of the device provides the electric field that separates and gathers the generated electrically charged carriers, which are then collected by wires attached to the solar cell.
Multiple cells are strung together in a protective package to form a PV module. Then many modules are interconnected to form an array. Balance of System (BOS) components are the final element of a working PV system.
To help you better understand what kind of solar panels make sense for your proposed system, there’s a simple recommendation you can keep in mind that will save time and help you make the best decisions for your home. It can be summarized as follows: If the homeowner wants to obtain the maximum power from his or her available rooftop space, then monocrystalline or polycrystalline solar modules will be the best choice. Which of these alternatives you choose will depend on several factors, as explained later in this chapter. Only under special circumstances and for certain special applications would I recommend that you consider thin-film solar cells.
Once you have a pretty good idea about the space issue and other specific conditions at your location, then the above criterion will determine which sections of the book you’ll want to focus on.
Let’s start with the most common types of solar panels on the market and list their benefits and disadvantages. Then we’ll look at a few typical scenarios in which certain types of PV solar modules would be better than others.
Between 85 and 90 percent of the world’s photovoltaics are based on some variation of silicon. In recent years, about 95 percent of all PV solar system shipments by US manufacturers to the residential sector were crystalline silicon solar panels.
The silicon used in PV solar cells takes many forms. The main difference between monocrystalline silicon cells and polycrystalline silicon cells is in the purity of the silicon, and this depends on the manufacturing process. But what does silicon purity really mean? The more perfectly aligned the silicon molecules are, the more efficient the solar cell will be at converting solar energy (sunlight) into electricity (the photoelectric effect).
The efficiency of solar panels goes hand-in-hand with the level of silicon purity in the cells that make up the panels, or modules. But the processes used to enhance the purity of silicon are complex and expensive. However, the energy conversion efficiency rating of the PV solar panel shouldn’t be your primary concern. As you’ll soon discover, cost and space efficiency are the key factors for most people in selecting the optimum PV solar system, as well as the number of panels or modules and the power or number of watts per panel.
What’s important to remember right now is that the total number of panels used for a PV rooftop installation, multiplied by the power rating in watts peak (Wp) of each panel, divided by 1,000, will give you the total power of the entire system in kWp. The significance of the term “peak” will be explained later.
The thin-film type of PV panel is often the most cost-effective choice for tropical applications or for hot, desert-like climates. Thin-film panels can produce up to 30 percent more energy per year in hot climates as compared to crystalline panels. Many consumers tend to analyze the different types of photovoltaic panels and make their decision based on the estimated kilowatt hours produced annually by the system, not on the watts peak (Wp) value. But you’ll see later in this chapter that there are other factors you’ll need to take into account besides the potential annual kWh produced.
Let’s take a moment to clarify what the Wp value really means. The watts peak figure, given for any photovoltaic panel, is not the output from that panel. The actual output depends on the surface temperature of the panel, the intensity of light reaching the panel (the Insolation Index), the average daily “sun hours” at the site location, and the angle (tilt to the horizontal plane) and east-west orientation (azimuth angle) of the array to the sun, as well as the type and model of panel being considered. Watts peak (Wp) is a figure obtained under controlled laboratory conditions that do not occur in real life. It’s the maximum output of the panel, under perfect conditions. It’s important to point out that these laboratory “Wp” conditions apply only to crystalline panels, not to thin-film panels.
The website energyinformative.org/solar-panel-comparison is one of the most comprehensive and up-to-date solar panel comparison resources on the Internet. The solar cell comparison table below provides a quick overview that will also be helpful. This chart lists the most commonly used solar cell technologies today, with their basic characteristics and summary specifications.
A compact array of six mono panels installed flush with the roof surface—a very typical mounting.
Thin-film solar cells include four sub-categories, defined as follows:
1. Amorphous silicon (A-Si)
2. Cadmium telluride (CdTe)
3. Copper indium gallium selenide (CIS/CIGS)
4. Organic (or polymer) solar cells (in early stages of research and development)
Before proceeding with your purchase, be aware that whichever PV solar technology you select, you must be diligent and careful to analyze the reputation of the available module manufacturers as well as their standard warranty terms. It really pays to read the fine print. You should look beyond efficiency ratings to the financial health and long-term prospects of the companies issuing these warranties. We’ll explore this issue in more detail below.
A close-up shot of a mono cell, the basic building block of a monocrystalline PV panel.
Invented in 1955, monocrystalline, meaning single crystal, is the original PV technology. Commercially, monocrystalline entered the market in the late 1970s and is well known for its durability. The useful life of monocrystalline solar modules is about 35 years. They’re consistent in performance and reliability. Single-crystal modules are composed of cells also called “wafers” cut from a cylindrical block of continuous crystal. Monocrystalline cells may be fully round, or they may be trimmed into other shapes. Because each cell is cut from a single crystal, it has a uniform color that’s dark blue or dark gray with a hint of blue.
Solar cells made of monocrystalline silicon (mono-Si), also called single-crystalline silicon cells (single-crystal-Si), are quite easily recognizable by their even coloring and uniform look, indicating high-purity silicon.
Monocrystalline and polycrystalline solar panels are easy to differentiate. Polycrystalline solar cells are perfectly rectangular, with no rounded edges. They typically have a speckled bright blue color.
Since they’re made out of the highest-grade silicon, monocrystalline solar panels have the highest efficiency rates, running from 16 to 18 percent, typically, over the last decade. In recent years, SunPower has produced the highest-efficiency solar panels on the US market to date. Their E20 series provides panel conversion efficiencies of up to 20.1 percent. SunPower more recently released their X-series, with an impressive efficiency rating of 21.5 percent.
In addition, monocrystalline silicon solar panels are the most space efficient. Since these solar panels yield the highest power outputs, they also require the least amount of space compared to any other type of solar panel. They produce up to four times the amount of electricity compared to most thin-film solar panels for the same panel surface area. This is good to remember if your available rooftop space is somewhat insufficient.
Furthermore, monocrystalline solar panels last the longest. Most solar panel manufacturers put a 25-year warranty on their monocrystalline solar panels. The monocrystalline silicon modules manufactured in the early 1980s are still functioning, according to many accounts.
Lastly, these particular solar panels tend to perform better than similarly rated polycrystalline solar panels under low-light conditions. For many climates, this also is an important consideration.
However, monocrystalline solar panels also have some disadvantages. They’re the most expensive of all photovoltaic solar module types. From a financial standpoint, a solar panel made of polycrystalline silicon might be a better choice for some homeowners, depending on the desired power output and available rooftop space.
Another downside is that if the solar panel is partially covered with shade, dirt, or snow, the entire array circuit can break down. Consider getting micro-inverters instead of the old standard conventional central inverters if you think shading or other obstructions such as snow might be a problem. Micro-inverters will make sure that the entire solar array isn’t affected by shade hitting only one or two of the panels in the array. The critically important topic of whether to choose micro-inverters or central or string inverters is discussed in more detail in Chapter 3.
The Czochralski process used to produce monocrystalline silicon is technically complex and requires very expensive equipment. This process creates large cylindrical ingots. Four sides are cut out of the ingots, and the four corners are rounded to make silicon wafers. Therefore, a significant amount of the original silicon ends up as waste. This is another factor that contributes to the higher cost of monocrystalline panels.
Finally, be aware that monocrystalline solar panels tend to be more efficient than the alternatives in hotter climates. The performance of all solar panel types, including monocrystalline, will suffer where average temperatures are much higher, but this is truer for polycrystalline solar panels. However, for most American homeowners, temperature won’t be a major concern.
Polycrystalline cells are made from a similar silicon material as that of monocrystalline cells, except that instead of being grown into a large single crystal, the raw material of polycrystalline cells is melted and poured into a mold. This mold forms the silicon into a square block that is then cut into square wafers, which waste less space and material than the round-cornered single-crystal mono-wafers. As the material cools, it crystallizes in an imperfect manner, forming random crystal boundaries and irregular color textures.
The efficiency of energy conversion for polycrystalline is slightly lower than monocrystalline cells of equal surface area. This means that the surface area per watt of energy produced by a polycrystalline module is greater than that of a monocrystalline or single-crystal module. The poly cells look different from the mono-or single-crystal cells, as their surface has a jumbled or speckled look with many variations of bright blue colors. In fact, they’re often quite beautiful.
Some companies have developed alternatives to the traditional molds, such as ribbon growth and growth of crystalline film on glass. Most crystalline silicon technologies yield similar results with high durability. Twenty-five-year warranties are common for crystalline silicon modules.
The silicon used to produce crystalline modules is derived from silicon sand. It’s the second most common element on earth, so why is it so expensive? Well, in order to produce the photovoltaic effect, the silicon must be purified to an extremely high degree. Such pure semiconductor grade silicon is very expensive to produce. It’s also in high demand in the electronics industry because it’s the base material for computer chips and many other devices. Crystalline solar cells are about as thick as a fingernail; therefore, an entire solar PV module uses a relatively large amount of silicon.
Regardless of the technique used in growing the crystals, the construction of finished modules from crystalline silicon cells is generally the same. The most common construction method involves laminating the cells between a tempered glass front and a plastic backing, and then applying a clear adhesive similar to that used in automotive safety glass between the layers. The sheets are rectangular and all have approximately the same dimensions, usually about 1 meter wide by 1.8 meters long. The laminated sheets are then framed around the four edges with a sturdy aluminum “U” channel. The finished panel is about five to six centimeters thick and weighs approximately 30 kilos, which can be easily handled by one installer. That being said, the mounting of a module onto its rooftop support framework is usually handled by two installers, as shown in many of the photographs in Chapter 10.
Two poly arrays on two different slopes of the same roof.
A small array of seven poly modules.
The first solar panels based on polycrystalline silicon, also known as polysilicon (p-Si) or multi-crystalline silicon (mc-Si), were introduced to the market in the 1980s. Unlike monocrystalline-based solar panels, polycrystalline solar panels do not require the Czochralski process.
Ultimately, the process used to make polycrystalline silicon cells and modules is simpler and costs less compared to monocrystalline. In addition, the amount of waste silicon in the manufacturing process of polycrystalline cells is much less compared to monocrystalline. This reduces the production costs of polycrystalline cells.
Polycrystalline solar panels tend to have slightly lower heat tolerance than monocrystalline. In practical terms, this means that they perform at a slightly lower level compared to monocrystalline solar panels in high ambient temperatures, for example over 40 degrees C (104 degrees F). Very high ambient temperatures can slightly shorten the panels’ useful lifespan. However, this effect is minor, and most homeowners don’t need to take it into account unless they live in a very dry, hot desert.
As compared to monocrystalline, the efficiency rating of polycrystalline-based solar panels is typically 14 to 16 percent, which is due to lower silicon purity. Its space efficiency is lower as well. You generally need to cover a nominally larger surface to generate the same amount of electrical power as you would generate with a solar panel made of monocrystalline silicon.
Another drawback to polycrystalline panels is their aesthetic appeal. Monocrystalline and thin-film solar panels can sometimes be more aesthetically pleasing since they have a more uniform look as compared to the irregular, speckled blue colors of polycrystalline silicon, as shown in the photograph below.
However, this doesn’t mean that every monocrystalline solar panel performs better than polycrystalline silicon panels. You must take into account your unique situation and its needs when comparing the two.
Imagine if a PV cell was made with a microscopically thin deposit of silicon instead of a thick wafer. It would use very little of the precious material. Now, imagine if it was deposited on a sheet of film or thin metal or glass, without the time-consuming and costly work of slicing wafers from ingots with special equipment. Imagine the individual cells deposited next to each other, instead of being mechanically assembled. That’s the idea behind thin-film technology. It is also called amorphous, meaning “not crystalline.” The active material may be silicon, or it may be a more exotic material such as cadmium telluride.
These thin-film panels can be made flexible and lightweight by using plastic glazing. Some flexible panels can tolerate a bullet hole without failing. Some perform slightly better than crystalline modules under low-light conditions, such as when the sky is slightly overcast with a thin layer of clouds. Many websites still claim that thin-film PV panels are less susceptible to losing power on the entire array when only one or two modules are shaded. However, these early claims of superior shade tolerance seem to have been exaggerated.
The major disadvantages of thin-film technology are lower efficiency and uncertain durability. Depending on the technology, thin-film module prototypes have reached efficiencies between 7 and 12 percent, and production modules typically operate at about 9 to 10 percent. Some predict that future module efficiencies will climb to between 11 and 13 percent. Lower efficiency means that more roof space and mounting hardware are required compared to monocrystalline or polycrystalline modules to produce the same power output. Thin-film materials also tend to be less stable than those used in crystalline panels, and thin-film can suffer relatively more efficiency degradation during the initial months of operation and beyond. However, thin-film technology is the subject of constant research. We will likely see many new thin-film products introduced in the coming years with higher efficiencies and longer warranties.
The market for thin-film PV grew appreciably starting in 2002. In recent years, about 5 percent of US photovoltaic module shipments to the residential sector have been based on thin-film technology. It continues to have a sizeable market for small electronic devices and special applications, including building-integrated photovoltaics (BIPV). Thin-film technology has also been popular for very large solar farms in deserts, where the land cost is very low and the solar insulation index is very high.
Two DIY installers holding a long, amorphous silicon thin-film panel that can easily adapt to a curved substrate or surface.
Thin-film solar cells are manufactured by depositing one or several very thin layers of photovoltaic material onto a substrate. They’re also known as “thin-film photovoltaic cells” (TFPV). The different types of thin-film solar cells are generally categorized by the kind of photovoltaic material that is deposited onto the substrate. Commercial production of thin-film solar cells is currently based on three basic types: amorphous silicon (A-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). Very recently, a fourth type has been developed, namely organic solar cells. Solar panels based on amorphous silicon, cadmium telluride, and copper indium gallium selenide are currently the only thin-film technologies commercially available on the market. Organic or polymer solar cells may be available for some applications by 2020.
A fairly common ground-mounted thin-film PV solar farm.
An organic solar cell or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers. An example of an organic photovoltaic is the polymer solar cell. As of late 2015, polymer solar cells were reported in research projects to have reached efficiencies of up to 10 percent. However, figures for production models will not be available for several years. These PV cells have low production costs and may be cost-effective for some photovoltaic applications. The main disadvantages associated with organic photovoltaic cells are low efficiency, low stability, and low strength compared to crystalline silicon solar cells. This type of organic solar cell is not yet considered commercially competitive, and the technology is still in the early stages of research and development. Therefore, the homeowner looking for a solar PV rooftop system should not seriously consider it.
Because their electrical power output is low, solar cells based on amorphous silicon have traditionally only been used for small-scale applications such as in-pocket or portable calculators. However, recent innovations have made them more attractive for larger scale applications. With a manufacturing technique called “stacking,” several layers of amorphous silicon solar cells can be combined, resulting in higher efficiency rates (in the 6 to 8 percent range). Only about 2 percent of the silicon used in crystalline silicon solar cells is required in the manufacture of amorphous silicon solar cells. This makes a-Si cells extremely cost competitive per watt if you ignore the cost and availability of the space required. On the other hand, stacking is a relatively expensive process.
Cadmium telluride (CdTe) photovoltaics make use of a photovoltaic technology that is based on the use of cadmium telluride thin-film, a semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride is the only thin-film solar panel technology that, in some cases, has surpassed the cost-efficiency of crystalline silicon solar panels for multi-megawatt systems. The average efficiency of solar panels made with cadmium telluride is generally considered to be in the range of 10 to 12 percent.
First Solar has installed over five gigawatts (GW) of cadmium telluride thin-film solar panels worldwide. First Solar holds the world record for CdTe PV module efficiency at 14.4 percent.
Flexible thin-film solar cells that can be produced by roll-to-roll manufacturing are a highly promising route to cheaper solar electricity. Scientists from Empa, the Swiss Federal Laboratories for Materials Science and Technology, have made significant progress in paving the way for the industrialization of flexible, lightweight, and low-cost cadmium telluride (CdTe) solar cells on metal foils. They also succeeded in increasing the efficiency rating of the cells from below 8 percent up to 11.5 percent by “doping” the cells with copper.
A ground-mounted cadmium telerium PV solar array used for research. Cadmium telerium is often referred to as “CdTe.”
After crystalline silicon, CdTe solar cells are the next most abundant photovoltaic product in the world, currently representing about 4 percent of the world market. CdTe thin-film solar cells can be manufactured quickly and inexpensively, providing a lower-cost alternative to conventional silicon-based technologies. The record efficiency for a laboratory CdTe solar cell is 18.7 percent, which is well above the efficiency of current commercial CdTe modules that run between 10 percent and 13 percent.
Polyimide film is a new material currently in development for use as a flexible superstrate for cadmium telluride (CdTe) thin-film photovoltaic modules. Because Kapton film is over 100 times thinner and 200 times lighter than the glass typically used for PV panels, there are inherent advantages in transitioning to flexible, film-based CdTe systems. High-speed and low-cost roll-to-roll adhesion technologies can be applied for high-throughput manufacturing of flexible solar cells on polymer film. The new polyimide film potentially enables significantly thinner and lighter-weight flexible modules that are easier to handle and less expensive to install, which would make them a candidate for many applications, including building-integrated photovoltaics.
However, due to low efficiencies and other limitations, as well as the premature stage of development of polyimide film PV technology, this type is not recommend to the homeowner looking for a PV solar rooftop system.
As it provides a solution to key issues like climate change and water scarcity, CdTe PV is considered the most eco-friendly technology among the available types, and it may provide some element of energy security. It’s also considered the most eco-efficient PV technology when comparing a range of applications, including installation on commercial rooftops or large-scale ground-mounted PV systems. Some claim that CdTe PV has the smallest carbon footprint, lowest water use, and fastest energy payback time of all solar technologies.
CIGS component elements are used to make thin-film solar cells (TFSC). Compared to the other thin-film technologies summarized above, CIGS solar cells have demonstrated the most potential in terms of efficiency. These solar cells contain lower amounts of the toxic material cadmium than is found in CdTe solar cells. Commercial production of flexible CIGS solar panels was initiated in Germany in 2011. The efficiency ratings for CIGS solar panels are in the range of 10 to 13 percent, but this may increase over time.
CIGS features much higher absorption than silicon, so a layer of CIGS can absorb more light than a silicon layer of the same thickness. With thin-film, some of the light-gathering efficiency is given up in exchange for the advantages of thinness. But with the highly absorptive CIGS, the efficiency trade-off is less severe than with silicon PV cells. The record efficiencies for thin-film CIGS cells are slightly lower than that of CIGS used in lab-scale, top-performance cells, which are rated at 19.9 percent efficiency. Compared with those achieved by other thin-film technologies such as cadmium telluride or amorphous silicon, this is the highest efficiency rating reported.
A ground-mounted solar array.
CIGS solar cells are not as efficient as crystalline silicon solar cells, for which the record efficiency is over 25 percent. However, many companies argue that CIGS is substantially cheaper due to lower fabrication costs and significantly lower material costs. A direct band gap material, CIGS has very strong light absorption. Two micrometers of CIGS is enough to absorb most of the sunlight that strikes it; a much greater thickness of crystalline silicon is required for the same amount of absorption.
The active layer of CIGS can be deposited directly onto molybdenum-coated glass sheets or steel bands. This takes less energy than growing large crystals, which is a necessary step in the manufacture of crystalline silicon solar cells. Also, unlike crystalline silicon, these substrates can be flexible, a notable advantage when it comes to design and fitting solar cells to curved surfaces, as demonstrated in the photos below.
Many thin-film solar cell types are still early stages of research and testing. Some seem to offer promising potential, and we can expect to see more of them in the future. Indeed, the initial attraction of CIGS was its promise of lower-cost manufacturing, both in terms of the materials required and in its streamlined, roll-to-roll manufacturing process. However, crystalline silicon market prices have decreased so much in recent years that this former advantage of CIGS has been erased.
Three CIGS arrays of four panels, each suspended by rope or cable demonstrate their flexibility.
An attractive example of BIPV with the PV solar system installed on this very steep, two-roof house in Colorado where there is often big snowfalls in winter.
C-Si (crystalline silicon) manufacturing has become much more streamlined and standardized, while CIGS remains a customized technology. And CIGS’s conversion efficiencies haven’t kept pace with c-Si. As of recently, Miasole was the current CIGS module record-holder, at 15.7 percent efficiency.
Lastly, I’ll briefly touch on the subject of building-integrated photovoltaics. Rather than being an individual type of solar cell technology, building-integrated photovoltaics have different methods of integration. BIPV can be developed with either crystalline or thin-film solar cells. They can be incorporated into facades, roofs, skylights, windows, walls, and other building surfaces that can be manufactured with one of the basic photovoltaic cell materials listed above. Smaller surfaces like covered walkways and solariums can also be designed and built as mini-BIPV projects.
If you have the extra money and want to seamlessly integrate photovoltaics with the rest of your home or condominium project, you might consider building-integrated photovoltaics, especially if your home is still in the design stage. These panels are extremely versatile and can be used to replace conventional building materials for practically any part of the building’s exterior. BIPV is increasingly being incorporated into the construction of new buildings as a principal or back-up source of electrical power, although existing buildings may also be retrofitted with similar technology. The advantage of building-integrated photovoltaics over more common nonintegrated systems is that the initial capital cost can be substantially offset by reducing the amount spent on building materials and labor that would normally be used to construct the roof or the other part of the building that the BIPV modules replace. These advantages make BIPV one of the fastest-growing segments of the photovoltaic industry for residential, commercial, and industrial applications.
After you’ve done some basic research by reading this book, and after you have a pretty good outline of your PV solar rooftop project, it’s a good idea to have your project evaluated by an expert. This will help you determine what type and quantity of solar panels would be best for your home.
One aspect to consider is space limitations. The majority of homeowners don’t have enough space for thin-film solar panels. In this case, crystalline silicon-based solar panels are usually your best choice. Regardless of space issues, though, you’ll likely want to choose between monocrystalline and polycrystalline PV modules. Furthermore, in many areas there are no residential solar installers who offer a thin-film solar panel option.
You’ll likely have a choice of different solar panel sizes. The 180, 200, and 220-watt rated solar panels (and even higher wattages) are usually the same physical size. They’re manufactured in exactly the same way but perform differently when tested, and hence they fall into different categories for power output. If available area is very limited, you’ll logically select the highest-rated power output for a particular physical size of module, and that will be monocrystalline.
Both monocrystalline and polycrystalline solar panels are good choices and offer similar advantages. Even though polycrystalline solar panels tend to be less space efficient and monocrystalline solar panels tend to produce more electrical power, this is not always the case. It would be nearly impossible to recommend one or the other without examining the alternative solar panels available, as well as your specific location and its physical conditions.
Monocrystalline solar panels are slightly more expensive but also slightly more space efficient. If you had one polycrystalline and one monocrystalline solar panel, both rated 220-watt, they would generate the same amount of electricity. But the one made of monocrystalline silicon would take up slightly less space, and this can be an important factor in deciding which type of PV module to use.
Two large arrays of poly panels mounted on the sloping roof of a low-rise commercial building.
In addition to the different PV technology descriptions and comparisons, there are numerous other factors and considerations you should take into account before making a final decision about which solar panel to buy.
For homes and buildings with ample roof space, a panel’s peak efficiency shouldn’t be the primary consideration. It’s more important to consider the system as a whole, balancing price with quality. Where space is really limited, efficiency considerations may outweigh the desired output of the solar system. These, of course, will carry a higher price tag. But for the budget-conscious homeowner, the number to look at will be dollars-per-watt for the entire PV system.
A small array of mono panels mounted flush to the surface of a wooden shingle roof. Wood roof shingles are normally made of cedar that has a natural attractive finish and they have a long useful life to match the expected useful life of PV panels.
A close-up shot of the mid-bracket securing two poly panels to the support railing below (not visible here).
In the end, the cost and performance of your system will depend not only on the panels you use, but also on the inverter you choose. If you hire a contractor, his or her installation costs will also come into play. Performance will also be affected by the east-west orientation (azimuth) of your roof and the tilt angle of your panels, which are commonly installed at an angle parallel to the roof.
It’s also important to look beyond module-efficiency ratings. As a prospective solar system owner, you’ll need to consider the company behind the product you’re buying. Although quality technology is important in the selection of solar panels, you must remember that both monocrystalline and polycrystalline silicon solar cells are proven technologies, and one should not automatically be considered better than the other.
Manufacturing equipment for silicon wafers is more readily available than ever. The market for PV solar panels is relatively easy for large companies to enter. A critical difference between quality manufacturers and others is whether the company in question invests seriously in research and development. R&D investment by a manufacturer is indicative of the company’s commitment to creating innovative and high-quality products. It also shows that the company is planning to be active in the market for a long time.
A small array of six poly panels on a small steep roof.
For most households, balancing affordability with reliability is important. Solar-power systems are expected to work for 30 years or more, and warranties are usually valid for 25 years. But warranties are only useful if the manufacturer remains a solvent company. Though it’s impossible to know what will happen to a company 15 or 25 years from now, it’s still wise to form an idea whether the manufacturer is financially sound and likely to be around for at least as long as the warranty period. If panels need repairing or replacing, the cost could become substantial if the warranty is of no use. Most of the PV module manufacturers are public companies. This makes it easy for you to ascertain if they’re financially solid and if they are seriously investing in R&D. These criteria will determine if the warranty is of real value.
A DIY installer inspecting his mono panels up on an aluminum ladder. This kind of ladder is not recommended for use when wiring the PV rooftop system as it can conduct electric current. I always insist that DIY PV system installers use only wooden ladders.
