Even though (Mono/Multi) Crystalline based Solar PV modules are the most popular type of solar panels in the world, Thin Film based Solar PV modules are fast catching up. While crystalline solar modules are more popular in colder regions like Europe/North America, Thin Film solar modules might be a very good option for countries with hot/tropical climate (with higher temperatures) like India, Singapore, Africa, Middle East and other equatorial regions.
Even though Thin Film solar modules are referred as a singular unit in this article, there are three popular types of Thin Film modules based on the materials used to make them - a-Si, CdTd, CIGS. The below mentioned parameters may be different for each type.
Advantages of Thin Film solar modules over Mono/Multi Crystalline solar modules:
- Thin Film modules perform better and have a higher power generating ability over crystalline modules in high-temperature regions as they have a lower negative temperature coefficient. Thin Film solar modules can give more kWh per KW installed in hot regions, comparatively.
- Higher the temperature, more is the efficiency-difference offered by the two technologies. Thin Film solar modules perform relatively better with increasing temperatures.
- Thin Film modules are more cost efficient than crystalline modules. But this factor depends on market conditions as crystalline modules are becoming increasingly cheaper due to lower silicon prices/mass production. The cost referred here is only for the solar modules and not for the related products like Inverter, etc. whose cost may vary depending on the project.
- Thin Film solar panels are flexible. They can be bent/folded and hence they are less susceptible to damage and give more flexibility during installation. There are Thin Film modules that can be installed on the (external) walls of a building, integrated into/instead of the roofs, fixed on roof tiles, etc.
- Thin Film solar panels are thin/light-weight. Due to this, they do not exert excessive loads on the roof and heavy supporting structures (to hold them) may not be required. If planned properly, installation costs may be reduced for Thin Film solar technologies.
- Thin Film solar panels sport a more aesthitic look and hence are preferred over crystalline solar panels for BIPV applications. BIPV = Building Integrated Photo Voltaic.
- Many large solar power plants in countries like India already use Thin Film solar panels.
- Thin Film modules can absorb solar radiation from a broader spectrum range that may even include UV and IR. Hence, they can work longer during the day and work better in rainy/cloudy conditions.
- Thin Film solar modules are not affected as much as crystalline modules due to the direction/angle of sun-light falling on it.
A white paper released by Photovoltaics International and authored by First Solar says that First Solar's 50 MW CdTe based Thin Film modules were able to generate 45 MW of power on a typical day in a region with hot climate, while crystalline modules in similar conditions would generate only 40 MW. The region where they recorded the above readings had the following conditions: 37 Degree C ambient temperature, 65 Degree C module temperature and 1000 W/sq-meter irradiance.
In the same white paper, it is noted that when solar modules need to be exposed to an average temperature greater than 25 Deg. C, Thin Film modules provide a better performance than Crystalline modules. You can download and read the white paper from here.
Let us also look at some limitations of Thin Film solar modules over Crystalline solar modules:
- Thin Film solar modules occupy more area/space (almost twice the area) than crystalline solar modules for the same capacity.
- Crystalline solar modules dominate the world-wide solar market (they dominate European/North American installations). They have much higher market share than Thin Film technologies.
- Crystalline solar modules are more reliable because they have been used for large scale power generation over the last three decades and it has been observed to be a very mature/reliable technology. The warranty failure rates are slightly lower for crystalline solar PV modules.
- Due to mass production (esp. in China) and due to the world-wide fall in the silicon prices (raw material), crystalline solar module costs are getting reduced quickly. The price difference between the two technologies is narrowing down and Thin Film solar modules no longer enjoy a huge price differential in colder regions (Europe) due to which they are becoming increasingly unpopular there, except for BIPV applications.
- When the ambient temperature is less than 25 Deg. C, Crystalline solar panels are more efficient than Thin Film solar panels.
