Homogenous Voltage-Matched Strings Using Three-Terminal Tandem Solar Cells: Fundamentals and End Losses

Progress in three‐terminal heterojunction bipolar transistor solar cells

“…In this respect, Gee 21 provided a partial solution that sacrifices two solar cells in the array and demands the output voltage of the top cell to be an integer multiple of the output voltage of the bottom cell. This approach was experimentally verified using AlGaAs/GaAs 3T‐HBTSCs by Zehender et al 22 The voltage‐matching configuration of three‐terminal devices has been extensively studied by McMahon et al 23 …”

“…19,20 In this respect, Gee 21 provided a partial solution that sacrifices two solar cells in the array and demands the output voltage of the top cell to be an integer multiple of the output voltage of the bottom cell. This approach was experimentally verified using AlGaAs/GaAs 3T-HBTSCs by Zehender et al 22 The voltage-matching configuration of threeterminal devices has been extensively studied by McMahon et al 23 An attractive solution to the stringing problem is to stack a 3T-HBTSC on top of a silicon cell, 24 as illustrated in Figure 3, interconnecting the two subcells by a conductive transparent adhesive such as the one described by Klein et al 25 Connecting the top contact (T) of the 3T-HBTSC to the rear contact of the Si cell leads to a twoterminal triple-junction solar cell using voltage matching. Remarkably, if the 3T-HBTSC is made of GaInP/GaAs, the resulting triple-junction device has a limiting efficiency of 43% (AM1.5G spectrum).…”

A framework for comparing the energy production of photovoltaic modules using 2-, 3-, and 4-terminal tandem cells

“…Because there are string-end losses for VM strings, the string conversion efficiency increases as the string length Please do not adjust margins Please do not adjust margins increases, and the impact of string-end losses is greater for stype than r-type tandems. 15 Overall, when the current-matching is nearly perfect, a 2T configuration is typically the best choice, but it does require a pair of optimum bandgaps and a tunnel junction or other ohmic connection between the subcells. If such a connection or bandgap combination is not possible, then a 4T configuration could be considered, but the optical and I 2 R losses associated with a 4T configuration would need to be carefully considered and controlled, as a typical 4T (as in Figure 1) has three contacts requiring a design compromise between optical transparency and lateral conduction, with their associated I 2 R and optical losses.…”

“…The fundamentals of voltage-matched (VM) strings formed from 3T tandems have been described by McMahon et al 15 (and references therein). This prior work showed how 2T strings can be created from 3T tandems using different subcell voltage-matching ratios ( V top / V bot ), and described the associated string-end losses.…”

Energy Yield Modelling of Textured Perovskite/Silicon Tandem Photovoltaics with Thick Perovskite Top Cells

“…This architecture promises to solve, both, the issue of current mismatch losses for the 2T architecture and of optical losses and high fabrication complexity for the 4T architecture. Even if delivering the highest energy yield (EY) at the cell level [14], when connecting the cells together, end-string losses are expected [21] and therefore further research is required to assess the performances of the 3T architecture.…”