Estimation and certification of energy production in photovoltaic power plants with bifacial modules

Last April 24 the conference entitled "Estimation and certification of energy production in photovoltaic power plants with bifacial modules" took place. It was provided by the Instituto de Energía Solar,

Last April 24 the conference entitled “Estimation and certification of energy production in photovoltaic power plants with bifacial modules” took place. It was provided by the Instituto de Energía Solar, which celebrates its 40th anniversary this year. The conference took place in the South Campus of the Universidad Politécnica de Madrid and had more than 150 attendees from both the academic and business sectors. QPV had the pleasure of collaborating as host with the IES-UPM.

The event began with a talk on the “Procedure for estimating and certifying production with bifacial modules” given by the university professor Eduardo Lorenzo. In this talk we learned some history of this technology, which began very early in Spain, dating back to the first developments in 1982. This early experience was accompanied by the development of engineering procedures necessary for the practical use of the modules: estimation of the radiation received by the back face, power measurement etc. From this experience, the IES-UPM learned that bifacial cells are a natural step in the path of high efficiency cells, which is precisely the one followed by photovoltaic technology in recent years, which leads him to believe that the weight of the bifacial is called to grow significantly in the coming years, as many analysts point out. It is expected that, by 2028, 35% of the modules will be of this technology.

Afterwards, the some technical concepts of these modules were discussed. For the bifacial case, it is necessary to define a PR that takes into account the actual radiation received by both sides. As in the monofacial case, this PR can be defined either using pyranometers or reference modules and either correcting to standard measurement conditions or not. The accuracy and variability of the index will be affected by the chosen method. It should be noted that, according to the tests carried out by the IES-UPM, a greater difference can be seen in the measurement between pyranometer and reference module in the bifacial case than in the monofacial, which makes the use of reference modules in the bifacial plants.

Finally, the possibilities of simulation of this technology with SISIFO were presented. This simulator, developed by the IES-UPM and bankable, incorporates the calculation of the radiation received by the bifacial modules following calculation procedures based on viewing angles, and incorporates it in the modeling and productivity estimation of bifacial power plants. In addition, on the same day, a simulation workshop was held to learn about the use of SISIFO in the design of facilities with this type of technology.

In the middle of the day, between the talk and the simulation workshop, attendees were able to visit the facilities of the IES-UPM in the South Campus. Among them, and in relation to the day, we could see the generator of bifacial modules where this technology is investigated and the calculation models developed are tested. Below, we can see some images of this:


[1] A. Luque, E. Lorenzo, G. Sala, and S. Lopez Romero, “Diffusing reflectors for bifacial photovoltaic panels”, Solar Cells, vol. 13, pp. 277-292, 1984.

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