As developers strive to increase their solar production while minimizing costs, bi-facial modules are becoming an important and up-and-coming solar technology that will help increase energy production. Bi-facial panels harvest energy from both sides by absorbing light reflections in addition to direct sunlight. This increases the overall energy production and reduces developers’ overall levelized cost of energy.  In contrast, traditional solar panels have a single face exposure, where opaque back-sheeting is installed preventing the back of the cell from generating any additional power. Some manufacturers of these bi-facial panels are touting up to a 30-percent increase in power, however most are not willing to guarantee this production at the time due to unknowns in the reflectivity of the background or the obstructions that could impact the reflection because of the racking system, harnesses, etc. Some suppliers will warrant the additional power generation if they are provided the conditions and design of the system. Due to their double-paned design, bi-facial panels also have a longer warranty period and reduced degradation compared to traditional solar panels   

Pitfalls to Consider

While bi-facial modules harvest energy from both sides of the panel by absorbing reflective light, there are a few drawbacks to using them that should be considered during the design phase. The extra energy production is highly dependent on the ground conditions. These variables can make it difficult to guarantee how much extra energy, if any, will be generated. Another potential pitfall of a bi-facial module system is the degree of variance of the reflective source. During the winter, reflectivity can occur from snow, which increases power production. However, during the rest of the year reflectivity of the surface might be much less. This differential may require increased costs in the overall design for a condition that occurs for a minor portion of the year. Additionally, current premiums on bi-facial modules and potentially higher mounting and installation costs over traditional modules may be a deterrent. But it is expected that the module costs will decline in the near term, and more racking systems will soon be available.

Best Practices for Implementation

 To overcome problems with bi-facial modules, it’s recommended that bi-facial panels be designed by an EPC familiar with these who can assist a developer in understanding the conditions of the site and choosing a system that fits the site conditions.

From a developer’s perspective, such as Macquarie’s Green Investment Group,  bi-facial technology represents an opportunity to achieve reliability, higher grid utilization and improved land utilization over the life of solar projects. To maximize the results, real and perceived challenges from an owner’s and financing party’s perspective, such as the need for site specific albedo data, accurate energy modeling and verification of reliability, must be addressed early-on. Working with qualified partners, these challenges can be tackled and bi-facial modules can be pursued. With manufacturing capacity ramping up and import tariffs stepping down, investors are seeing a strong case for the deployment of bi-facial technology.

The market for bi-facial modules continues to grow and is becoming more of an attractive alternative to traditional panels, as these modules can become a more reliable and cost-effective solution.

Author: Ryan Lewis, senior estimator, PCL Construction and Jorge Martinez, vice president, Macquarie’s Capital/Green Investment Group