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RESEARCH TOPIC: Solar module, Laser and the energy required to power the laser cutting machine.
Comprehensive Guide to Solar Panel Types
The push for renewable energy sources has led to a surge in solar energy use. In the past decade alone,
the solar industry grew by almost 50%, buoyed by federal support such as the Solar Investment Tax
Credit and strong commercial and industrial demand for clean energy.
As the solar sector continues to rise, it’s worth studying the backbone of the solar industry: solar panels.
This guide will illustrate the different types of solar panels available on the market today, their strengths
and weaknesses, and which is best suited for specific use cases.
What is a Solar Panel?
Solar panels are used to collect solar energy from the sun and convert it into electricity.
The typical solar panel is composed of individual solar cells, each of which is made from layers of silicon,
boron and phosphorus. The boron layer provides the positive charge, the phosphorus layer provides the
negative charge, and the silicon wafer acts as the semiconductor.
When the sun’s photons strike the surface of the panel, it knocks out electrons from the silicon
“sandwich” and into the electric field generated by the solar cells. This results in a directional current,
which is then harnessed into usable power.
solar module
The entire process is called the photovoltaic effect, which is why solar panels are also known as
photovoltaic panels or PV panels. A typical solar panel contains 60, 72, or 90 individual solar cells.
The 4 Main Types of Solar Panels
There are 4 major types of solar panels available on the market today: monocrystalline, polycrystalline,
PERC, and thin-film panels.
Monocrystalline solar panels
Also known as single-crystal panels, these are made from a single pure silicon crystal that is cut into
several wafers. Since they are made from pure silicon, they can be readily identified by their dark black
color. The use of pure silicon also makes monocrystalline panels the most space-efficient and longest-
lasting among all three solar panel types.
However, this comes at a cost — a lot of silicon is wasted to produce one monocrystalline cell,
sometimes reaching over 50%. This results in a hefty price tag.
Polycrystalline solar panels
As the name implies, these come from different silicon crystals instead of one. The silicon fragments are
melted and poured into a square mold. This makes polycrystalline cells much more affordable since
there is hardly any wastage, and gives them that characteristic square shape.
However, this also makes them less efficient in terms of energy conversion and space, since their silicon
purity and construction are lower than monocrystalline panels. They also have lower heat tolerance,
which means they are less efficient in high-temperature environments.
Passivated Emitter and Rear Cell (PERC) panels
PERC solar panels are an improvement of the traditional monocrystalline cell. This relatively new
technology adds a passivation layer in the rear surface of the cell that enhances efficiency in several
ways:
It reflects light back into the cell, increasing the amount of solar radiation that gets absorbed.
It reduces the natural tendency of electrons to recombine and inhibit the flow of electrons in the
system.
It allows greater wavelengths of light to be reflected. Light waves over 1,180nm can’t be absorbed by
silicon wafers and simply pass through, so they end up heating the cell’s metal back sheet and reduce its
efficiency. The passivation layer reflects these higher wavelengths and stops them from heating up the
back sheet
PERC panels allow greater solar energy collection in a smaller physical footprint, which makes them ideal
for limited spaces. They are only slightly more expensive to produce than traditional panels, due to the
added materials needed, but they can be manufactured on the same equipment, and can end up having
a lower average cost per watt due to their efficiency.
To get a better feel for the benefits of PERC panels, check out our blog 5 Important Benefits of PERC
Solar Panels You Need to Know.
Thin-film solar panels
Thin-film panels are characterized by very fine layers that are thin enough to be flexible. Each panel does
not require a frame backing, making them lighter and easier to install. Unlike crystalline silicon panels
that come in standardized sizes of 60, 72, and 96-cell counts, thin-film panels can come in different sizes
to suit specific needs. However, they are less efficient than typical silicon solar panels.
Thin-Film Solar Panel Variations
Unlike crystalline panels that use silicon, thin-film solar panels are made from different materials. These
are:
Cadmium telluride (CdTe)
Amorphous silicon (a-Si)
Copper indium gallium selenide (CIGS)
Cadmium telluride (CdTe)
CdTe has the same low-cost advantage as polycrystalline cells while possessing the lowest carbon
footprint, water requirement, and energy payback time of all solar panels types. However, the toxic
nature of cadmium makes recycling more expensive than other materials.
Amorphous silicon (a-Si)
Amorphous silicon panels (A-Si) derive their name from their shapeless nature. Unlike mono-and
polycrystalline solar cells, the silicon is not structured on the molecular level.
On average, an a-Si cell requires only a fraction of the silicon needed to produce typical silicon cells. This
allows them to have the lowest production cost, at the expense of efficiency. This is why a-Si panels are
suited for applications that require very little power, such as pocket calculators.
Copper indium gallium selenide (CIGS)
CIGS panels use a thin layer of copper, indium, gallium, and selenium deposited on a glass or plastic
backing. The combination of these elements results in the highest efficiency among thin-panel types,
though still not as efficient as crystalline silicon panels.
Solar Panel Types by Efficiency
Among all panel types, crystalline solar panels have the highest efficiency.
Monocrystalline panels have an efficiency rating over 20%.
PERC panels add an extra 5% efficiency thanks to their passivation layer.
Polycrystalline panels hover somewhere between 15-17%.
In contrast, thin-film panels are usually 2-3% less efficient than crystalline silicon. On average:
CIGS panels have an efficiency range of 13-15%.
CdTe ranges between 9-11%.
a-Si have the lowest efficiency at 6-8%.
Panel type Efficiency
PERC Highest (5% more than monocrystalline)
Monocrystalline 20% and up
Polycrystalline 15-17%
Copper indium gallium selenide (CIGS) 13-15%
Cadmium telluride (CdTe) 9-11%
Amorphous silicon (a-Si) 6-8%
Solar Panel Types by Power Capacity
Monocrystalline cells have the highest power capacity, thanks to their single-crystal construction that
allows a higher output rating in a smaller package. Most monocrystalline panels can generate up to
300w of power capacity.
Recent advances in solar technology have allowed polycrystalline panels to bridge the gap. A standard
60-cell polycrystalline panel is now capable of producing between 240-300w. However, monocrystalline
panels still beat polycrystalline in terms of power capacity per cell.
Because thin-film panels don’t come in uniform sizes, there is no standard measure of power capacity,
and the capacity of one thin-film panel will differ from another based on its physical size. In general,
given the same physical footprint, conventional crystalline panels output more power than a thin-film
panel of the same size.
Solar Panel Types by Cost
Monocrystalline panels (or modules as they are technically known) carry a hefty price tag, due to its
energy-intensive and inefficient manufacturing process with only a 50% yield for every silicon crystal.
Polycrystalline modules are cheaper because they make use of the crystal fragments leftover from
monocrystalline production, which results in a simpler manufacturing process and lower production
costs.
Among thin-film solar panels, CIGS is the most expensive, followed by CdTe and amorphous silicon.
Apart from the lower acquisition cost, thin-film modules can be easier to install thanks to their lighter
weight and flexibility, which lowers the cost of labor.
While the total cost of residential systems has declined by more than 65% over the last decade, the soft
cost of a system has actually risen from 58% of total system cost in 2014 to 65% in 2020.
For more information about soft costs, check out our article on the soft costs in the solar industry, and
what’s being done to reduce them.
Panel (Module) type Average Cost per Watt
PERC $0.32-$0.65
Monocrystalline $1 – $1.50
Polycrystalline $0.70 – $1
Copper indium gallium selenide (CIGS) $0.60 – $0.70
Cadmium telluride (CdTe) $0.50 – $0.60
Amorphous silicon (a-Si) $0.43 – $0.50
Note that these figures don’t include the cost of installation and labor. With labor and other overhead
factors, the total can rise to $2.50 to $3.50 per watt.
Other Factors to Consider
Temperature
The temperature of a solar panel can affect its ability to generate energy. This loss of output is reflected
through the temperature coefficient, which is a measure of the panel’s decrease in power output for
every 1°C rise over 25°C (77°F).
Monocrystalline and polycrystalline panels have a temperature coefficient between -0.3% / °C to -0.5% /
°C, while thin-film panels are closer to -0.2% / °C. This means that thin-film panels can be a good option
for hotter environments or places that experience more sunlight throughout the year.
Fire rating
The updated International Building Code of 2012 requires solar panels to match the fire rating of the
roof where they are installed. This is to ensure that the modules do not accelerate the spread of flames
in the event of a fire. (California goes one step further by requiring the whole PV system, which includes
the racking system, to have the same fire rating).
As such, solar panels now carry the same classification rating as roofs:
Class A
effective against severe fire test exposure
flame spread should not exceed 6 feet
required for wildland-urban interface areas, or areas with high fire severity and wildfire risk
Class B
effective against moderate fire test exposure
flame spread should not exceed 8 feet
Class C
effective against light fire test exposure
flame spread should not go beyond 13 feet
Hail rating
Solar panels are also tested for hail impacts.
UL 1703 and UL 61703 standards address hail storms, by dropping 2-inch solid steel spheres on solar
panels from a height of 51 inches, and by firing 1-inch ice balls on PV panels with a pneumatic cannon to
simulate hail impacts.
Because of their thicker construction, crystalline panels can withstand hail hitting at speeds of up to
50mph, while thin-film solar panels carry a lower rating due to their thin and flexible nature.
Hurricane rating
While there is no formal solar classification rating for hurricanes, the Department of Energy recently
expanded its recommended design specifications for solar panels to safeguard against severe weather.
The new recommendations include:
Modules with the highest ASTM E1830-15 rating for snow and wind loading in both the front and back.
Fasteners with true locking capability based on DIN 65151 standard
The use of through-bolting modules with locking fasteners instead of clamping fasteners
The use of 3-frame rail systems for improved rigidity and support against twisting
Tubular frames over open-shaped C channels
Perimeter fencing around PV systems to slow down wind forces
Light-Induced Degradation (LID)
LID is a performance loss commonly seen in crystalline panels during the first few hours of sun exposure.
This happens when sunlight reacts with oxygen traces left over from the manufacturing process, which
affects the silicon lattice structure.
The LID loss is directly tied to the manufacturing quality and can range from 1-3%.
Summary: Solar Panel Types Compared
PERC Monocrystalline Polycrystalline Thin-film
Initial Cost Highest High Middle Highest to lowest:
CIGS
CdTe
a-Si
Efficiency Highest (5% more than monocrystalline)20% and up 15-17% CIGS: 13-15%
CdTe: 9-11%
a-Si: 6-8%
Appearance Black with rounded edges Black with rounded edges Blue with square edges
Depends on the thin-film variant
Advantages Requires least space
Most efficient
Highest power capacity
Less expensive alternative to PERC panels without the passivating layer Middle option in terms of cost,
efficiency and power capacity Lowest costEasier to install
Disadvantages Most expensive initially
Some earlier panels suffered from light and elevated temperature induced degradation
High initial cost
Low yield in the manufacturing process
Low heat tolerance, not suitable in hot environments Shorter lifespan than crystalline panels requires
more space
Least efficient
So, Which Solar Panel Type Should You Use?
As crystalline and thin-film panels have their own pros and cons, the choice of solar panel ultimately
comes down to your specific property and condition settings.
Limited Space
Those living in a dense area with limited space should opt for highly efficient monocrystalline modules
to make the most of the physical space and maximize utility savings. If budget permits, going for PERC
panels can lower energy generation costs even more in the long run.
Large Properties
Those with a sufficiently larger property can save on upfront costs by using polycrystalline solar panels,
where a bigger panel footprint can offset the lower panel efficiency. However, a larger footprint could
also mean added labor costs, so it’s not necessarily cheaper to get a higher quantity of less expensive
panels. While the initial cost may be low, it may eventually be offset by reduced efficiency and higher
operating expenses in the long term.
As for thin-film solar panels, these are best suited for locations where the heavy and labor-intensive
installation of crystalline silicon is not feasible. Such locations can include commercial buildings with
tight spaces or thin roofs; compact spaces such as recreational vehicles and watercraft; and areas that
require flexible installation instead of rigid paneling.
Keep in mind that solar panels are designed for long-term installation, which can be as long as 25 years.
So whatever type you choose to go with, make sure to do your homework to ensure that it’s the best
option for your needs.
• The power obtainable from a single solar module which is about 300watt depending on the intensity
of sunlight ( brightness) 🔅 which might not be constant throughout the day.