Bifacial solar cells and modules are making a big comeback as the photovoltaic industry is looking for more ways to get more power out of the extant solar panel technologies. Let us take a closer look at what bifacial solar panels are and how they actually work.
HOW DO BIFACIAL CELLS WORK?
Bifacial cells are solar cells that are designed to allow the entry of light from both sides. They employ a standard front surface design that is very similar to the ones that are used in screen printed solar cells that are practically the industry standard. The only major difference is the structure of the rear surface. It is not covered with reflective aluminum. Instead, a finger grid is used to allow the passage of sunlight through the back.
The silicon material that they use in bifacial cells is of a much higher quality, which makes it possible for the photogenerated charges on the rear surface to contribute to the power production as they travel towards the front surface. The design also makes it necessary to use transparent materials on either side of the module.
Solar Panels Diagram
Traditionally, bifacial cells were used in building integrated photovoltaic applications and in areas where most of the solar energy is in the form of diffused sunlight that has bounced off the ground and all the surrounding objects (snow prone areas and extreme latitudes). However, with the plateauing of peak efficiencies and cheaper solar glasses, bifacial modules are back in the limelight.
To match the photovoltaic generation profile with the onsite demand, most of the consumers go for an east-west orientation. Half of the panels are tilted towards the east and the other half are tilted towards the west, for better generation peaks in the mornings and afternoons respectively. The double peak profile better matches the electricity use onsite, especially for commercial and residential installations.
This approach will work even better if we employ vertically installed bifacial modules, which would cut down the number of required modules by more than half. Not only will this setup benefit from the two generation peaks, it will also benefit from all the diffuse light that enters the module from the indirect side.
When comparing the financial merits of bifacial solar panels against single-sided modules, we should consider the leveled cost of electricity and not just the dollars-per-watt cost of the respective modules. For photovoltaic consumers who are connected to the grid, the ability to match the onsite demand with the photovoltaic generation profiles – thereby maximizing the use of the generated photovoltaic electricity rather than feeding it back into the American grids at a reduced rate – can significantly boost the returns on solar panel investment, in spite of the slightly higher upfront cost of the bifacial solar module. You get a better bell curve distribution of generated power and the maintenance costs are pretty much the same. So, if you are planning to go for one, it helps to know that the benefits clearly outweigh the drawbacks.