Luminescent solar concentrators (LSCs) generally consist of transparent polymer sheets doped with luminescent species. Incident sunlight is absorbed by the luminescent species and emitted with high quantum efficiency, such that emitted light is trapped in the sheet and travels to the edges where it can be collected by solar cells. LSCs offer potentially lower cost per Wp. This paper reviews results mainly obtained within the framework of the Fullspectrum project. Two modeling approaches are presented, i.e., a thermodynamic and a ray-trace one, as well as experimental results, with a focus on LSC stability.

Spectral conversion of sunlight is a promising route to reduce spectral mismatch losses that are responsible for the major part of the efficiency losses in solar cells. Both upconversion and downconversion materials are presently explored. In an upconversion process, photons with an energy lower than the band gap of the solar cell are converted to higher energy photons. These higher photons are directed back to the solar cell and absorbed, thus increasing the efficiency. Different types of upconverter materials are investigated, based on luminescent ions or organic molecules. Proof of principle experiments with lanthanide ion based upconverters have indicated that the benefit of an upconversion layer is limited by the high light intensities needed to reach high upconversion quantum efficiencies. To address this limitation, upconverter materials may be combined with quantum dots or plasmonic particles to enhance the upconversion efficiency and improve the feasibility of applying upconverters in commercial solar cells.

Research and development of silicon heterojunction (SHJ) solar cells has seen a marked increase since the recent expiry of core patents describing SHJ technology. SHJ solar cells are expected to offer various cost benefits compared to conventional crystalline silicon solar cells. This paper analyses the production costs associated with five different SHJ cell designs, including an interdigitated back-contacted (IBC) design. Using life-cycle costing, we analyzed the current cost breakdown of these SHJ designs, and compared them to conventional diffused junction monocrystalline silicon modules. Coupling the results for current designs with literature data on technological improvements, we also present a prospective analysis of production costs for the five SHJ cells and modules.For current designs, module costs were calculated to be 0.48–0.56 USD per Watt-peak (Wp) for SHJ modules, compared to 0.50USD/Wp for a conventional c-Si module. The efficiency bonus for SHJ modules compared to conventional c-Si modules is offset by a strong increase in metallization costs for SHJ designs, as comparatively large amounts of low-temperature silver-paste are required. For module materials, the requirement for conductive adhesives results in a small cost penalty for SHJ modules compared to c-Si modules, which is more than balanced by the effect of higher efficiency in SHJ modules.Our prospective study showed that improvements in cell processing and module design could result in a significant drop in production costs for all module types studied. The SHJ modules gain much advantage by reducing and replacing silver consumption, increased cell efficiency and thinner wafers and have prospective production costs of 0.29–0.35USD/Wp. Conventional c-Si module cost is less sensitive to silver paste consumption, limiting the potential for cost reduction, and has prospective production costs of 0.33USD/Wp. Replacement of indium-tin-oxide was not found to contribute substantially to a reduction in module costs