As tandem PV moves closer to commercial production, testing needs to keep pace. With different cells responding to different parts of the spectrum, accurately measuring performance means taking a more flexible approach. Multi-channel LED simulation could offer a simpler way to characterise individual devices and assess current matching, without the complexity of traditional spectral response testing.
Solar technology is moving into its next phase, with multi-junction devices, particularly silicon-perovskite tandems, edging closer to commercial production. Silicon remains the workhorse of the global solar industry, but tandem cells could capture more energy by combining materials that respond to different parts of the solar spectrum.
That also makes them more demanding to test. Unlike a conventional silicon cell, a tandem device’s performance depends not just on how much light reaches it, but on which wavelengths are present. Understanding that spectral response is therefore becoming an increasingly important part of measuring how these devices perform.
The importance of current matching in multi-junction devices
The power output of multi-junction PV devices is strongly linked to the current generated by each sub-cell. Because the sub-cells are typically connected in series, the junction producing the lowest current limits the current of the entire device. Achieving an appropriate current balance between the junctions is therefore important.
The optimum balance depends on the application and on trade-offs involving factors such as stability, degradation and materials. It also depends on the irradiation spectrum because each junction absorbs light over different wavelength ranges1.