Process for optimising the service life of a bifacial multijunction photovoltaic module and photovoltaic module or panel suited to this process

A method for lifetime optimization a two-sided photovoltaic module comprising at least one multi-junction stack, for which a first side of the module, under which is located a first junction layer of said stack, is exposed to the sun at the beginning of life of the module in a base position of the module, referred to as first-life position, and for which a last junction layer of said multi-junction stack, of two-sided type is arranged under a second side of the module not exposed to the sun receiving diffuse and reflected light under the module and also a part of light passing through the stack, wherein the method comprises:

• (a) measuring a first irradiance IRup on the side of the module exposed to the sun and a second irradiance IRlow on the side of the module not exposed to the sun, when the first side of the module is exposed to the sun;
• (b) measuring the output power PFM from the full module;
• (c) calculating the estimated output power PE1 of each junction layer of the multi-junction stack taken individually when the first side is the side exposed to the sun;
• (d) calculating an estimated output power for said last junction layer PLL of the module as a function of the first irradiance in a turned over position of the module, called second-life position, where the second side of the module becomes the side exposed to the sun and the first side of the module becomes the side not exposed to the sun;
• (e) comparing said estimated output power of said last junction layer PLL with the output power of the full module PFM measured when the first side is the side of the module exposed to the sun,
• to provide a recommendation for turning over the module when the output power of the full module PFM in the base position becomes less than the estimated output power of said last junction layer PLL in the turned over position of the module.