Which Type of Solar Panel Suits You?
Solar plants are grabbing eyeballs of all commercial, industrial and residential consumers of electricity. On the supply side, manufacturers are competing on research to bring better solar panels and as a result, consumers now find many options in terms of solar panels technology. In this article, we explore different types of solar panels and and try to find which type of panels will suit your needs the best.
Solar panels are made of solar cells. Based on the materials used for solar cells, solar panels are classified as:
|Panel Type||Solar Cell Material||Features|
|Crystalline||Silicon Crystals||1. Efficiency(~16-24 %) high compared to thin-film and amorphous.
2. Costs higher compared to thin film and amorphous
3. Almost all commercial applications use crystalline solar panels.
|Thin Film||Combination of materials like Silicon, Cadmium, Copper etc.||1. Efficiency(~10-12 %) lesser compared to crystalline panels.
2. Costs lesser comapred to crystalline.
3. Not preferred in many applications as their cost vs efficiency is not attractive.
4. Suitable in applications where space is not a constraint or flexible panels are required.
|Amorphous||Amorphous Silicon||1. Efficiency(~7 %) is very low.
2. Costs low compared to thin-film and crystalline.
3. Used for small applications like powering hand calculators.
In this article, we focus on crystalline solar panels as they are the most used panel for commercial applications.
Crystalline solar panels can be classified as
1. Standard Crystalline
2. PERC Crystalline
3. Bi-facial Crystalline
Solar cells used in standard crystalline panels receive sunlight on the top side and convert light energy into electricity. The most popular panels in this type as of 2019 are :
In PERC crystalline panels, a light reflective layer at the back of solar cell is used. As a result, solar cells use reflected light from the back surface as well as direct light from the top side.
Standard Panels vs. PERC Panels
With reflective layer, light losses reduce and efficiency improves. The overall efficiency of PERC panels is ~2% higher than standard crystalline panels. Standard panels have an efficiency of ~ 16-17%.
PERC panels have been in use for over 10 years. As the costs were high, they were not widely deployed as compared to standard crystalline panels. However, in recent times, PERC panel prices dropped and have come closer to standard panels. As of Mar 2019, there is about ~4-5 USD cents difference between PERC and standard panels.
The most popular panel in PERC technology is
1. 72 cell Mono PERC(360-390Wp)
2. 144 Half-cut Poly PERC (340-360Wp)
3. 144 Half-cut Mono PERC (380 – 410Wp)*
72 Cells vs. 144 Half-Cut Cell Panels
In 144 half-cut panels, standard 72 cells are cut into two halves to get 144 half-cut cells. These cells are arranged in a way to split the current into two halves while cross-section of current travel path remains the same. As the cross-section does not change but the current level decrease, the resistive losses in 144 half-cut cells are lower and the efficiency is higher compared to 72 cell panel.
Advantages of using a half-cell module-:
1. Half-cut cells improve efficiency by about 1.5-2% as compared to 72 cell panel.
2. Lesser risk of Point mechanical damage.
144 half-cut poly PERC panels are being deployed in fields recently. 144 half-cut mono PERC are in the testing phase by some manufacturers and in the commercial phase by other manufacturers.
As the name suggests, bi-facial crystalline solar panels have two faces or have cells on both sides of a panel. This enables the panel to produce more energy by absorbing light from the back as well as front sides.
Bi-facial panels are yet to become fully commercial and mature. At this point of time, they are considered largely for utility applications.
Which Solar Panel Suits Best for My Need?
To answer the question, let us look at what parameters are important for comparing solar panels. Two parameters are the most important for comparing panels. They are Performance and Price.
There are many metrics related to the performance of solar panels. But, the two most important performance factors for solar panels are efficiency and durability.
The efficiency of a solar panel tells about the space you need to produce fixed energy. If a panel is more efficient, then one needs less space as compared to a less efficient panel to produce the same energy. Higher the efficiency the better a panel is.
Price is one of the most important factors to decide the worth of solar. It varies from one panel type to another.
On the three parameters, we compared crystalline panels of different types in below table.
|S. No.||Technology||Standard Size |
|Efficiency (%)||Price (INR/Wp)||~Return on Investment* (%)|
|1.||Poly crystalline-72 Cells||330||17.0||24||18 %|
|2.||Mono crystalline (PERC)- 72 Cells||360||18.5||27||16 %|
|3.||Poly crystalline (PERC)-144 Cells||360||18.2||27||16 %|
|4.||Mono crystalline (PERC)- 144 Cells||380||19.2||28||14 %|
*Return on Investment is an indicative figure used to illustrate the difference between types of panels. It depends on assumptions on the tariff, interest rates etc.
The selection of the type of panel depends on
If there are no space constraints to produce the required energy, then the least efficient technology is the most suitable. In practical, space is a constraint. Then, the choice comes down to expected return vs. the energy production that you are comfortable with.