Energetica India Magazine May-June 2021

SOLAR POWER Increased distance between trackers implies more hours of tracking and, therefore, increased module front side gen- eration. In other words, decreased generation resulting from tracker deviation during backtracking is lower. This is true for projects equipped with both bifacial modules and Monofacial modules. Maximum tracker angle is another key factor. For the same GCR, trackers with a larger tracking angle can operate lon- ger in tracking mode (directly facing the Sun), thus generating more power by direct irradiation. When solar elevation exceeds the limit angle, tracking stops and energy is lost. Increased Rear Radiation with Height Bifacial module height has a direct impact on power genera- tion because as module distance from the ground increases, bifacial module rear side irradiation does too. Module distance from the ground facilitates diffuse radiation penetration and increased view factor. Optimal bifacial module height ranges between 2 to 2.5 meters Similarly to Monofacial modules, shading has a negative im- pact on bifacial module performance. Some analysts suggest that module mounting system shading could result in a rear irradiation loss of up to 20%. In the case of standard 1P solar trackers, the torque tube is a significant module shading source. A number of analyses point out the fact that projected 1P tracker torque tube shading pro- jection varies along the module depending on the time of the day, potentially reaching an irradiation decrease of up to 15% with a distinctive peak. Specific interference location does not only favor reduced rear radiation, but also increases mismatch losses and may contribute to overheating of some cells, and as a result, a premature module degradation. Influence of Height and Pitch - Cooling The electrical conversion efficiency of a PV cell decreases as temperature increases, meaning the power generation of a module, both bifacial and Monofacial, increases as module cooling improves. The downside on bifacial modules is that they generate more heat due to rear side irradiation capture, meaning they tend to work at higher temperatures and, there- fore, need additional cooling. According to temperature distribution along the tracker, it de- creases as distance from the ground increases. This trend applies to both 1Pand 2P tracker, meaning the average tem- perature of the lower module in a 2P tracker is similar to that of the 1P tracker module. As for the upper module, temperature values are lower. Measurements show that the average differ- ence of 6 degrees Celsius translates into a power gain for the entire plant of about 1.2%. Enhanced cooling is caused by three factors. On the one hand, 2P tracker modules are further away from the ground, hence favoring air flow circulation under the tracker. On the other hand, aisles are twice as wide, hence favoring improved air inlet between rows. Lastly, SF7 Bifacial tracker design al- lows cool air to flow through the gap in the central part of the structure. According to Lujia Xu, a postdoc researcher at Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) “Lowering module temperature by around three degrees Cel- sius could bring about the same improvement to levelized cost of electricity (LCOE) at project level as a 1% increase in mod- ule efficiency. Findings also show that reducing operating tem - perature can also greatly increase a module’s lifetime” Analyzing the module cooling effect in a market like India where summer temperature goes to 50 degrees in many parts can definitely help developers in gaining the lowest LCOE with best tracking system design and module combination. 49 energetica INDIA- May-June_2021