Heterojunction technology can absorb a wide spectrum of sunlight. It applies thin layers of solar cells into a new structure, producing a new type of solar cell. ‘Normal’ solar cells employ only
one layer of photovoltaic materials, while heterojunction panels have three layers of photovoltaic material. HJT has one crystalline silicon solar cell sandwiched between two amorphous silicon (a-Si) solar cells.
So, what is an a-Si solar cell? The a-Si solar cell is not structured in a regular way. This type of solar cell is not as efficient as conventional crystalline silicon at converting sunlight into electricity, however it can harness the part of the “sunlight spectrum” which crystalline silicon
cannot absorb to generate electricity. It also costs much less to produce.
Thus, HJT solar cells that have a-Si in its front and back are more efficient because amorphous silicon layers absorb the extra photons that could not be captured by the middle crystalline silicon layer.