Abstract
The challenge in solar energy today is not the cost of photovoltaic (PV) electricity generation, already competing with fossil fuel prices, but rather utility-scale energy storage and flexibility in supply. Low-cost thermal energy storage (TES) exists but relies on expensive heat engines. Here, we introduce the concept of luminescent solar power (LSP), where sunlight is absorbed in a photoluminescent (PL) absorber, followed by red-shifted PL emission matched to an adjacent PV cell’s band edge. This way the PV cell operates nearly as efficiently as under direct illumination but with minimal excessive heat. The PL absorber temperature rises because of thermalization, allowing it to store the excessive heat, which can later be converted into electricity. Tailored luminescent materials that support an additional 1.5 kW h PV electricity for every 1 kW h of (virtual) heat engine electricity with a dynamic shift between the two sources are experimentally demonstrated. Such an ideal hybrid system may lead to a potential reduction in the cost of electricity for a base-load solution.
Highlights
Concentrated solar power (CSP) denotes the technology wherein a thermal absorber is heated by the concentrated sunlight, enabling thermal energy storage (TES) for dispatchable generation.[1−3] CSP electricity generation is considered expensive in terms of the levelized cost of electricity (LCOE), roughly 7 ¢/kW h nowadays, in regions with high solar flux,[4,5] compared to 2 ¢/kW h6 for Si-based photovoltaics (PVs) in similar regional conditions
Hybrid-concentrated photovoltaic/thermal (PV/ T)[18−20] methods, where electricity generation by a PV cell is performed in parallel to the extraction of unused heat, allowing TES, can potentially meet the requirements for constructing the sought after renewable base-load solution
Heat transfer fluid (HTF) stores and later transfers the heat to a heat engine for electricity generation
Summary
Concentrated solar power (CSP) denotes the technology wherein a thermal absorber is heated by the concentrated sunlight, enabling thermal energy storage (TES) for dispatchable generation.[1−3] CSP electricity generation is considered expensive in terms of the levelized cost of electricity (LCOE), roughly 7 ¢/kW h nowadays, in regions with high solar flux,[4,5] compared to 2 ¢/kW h6 for Si-based photovoltaics (PVs) in similar regional conditions. Projection of a base-load solar energy LCOE below 3 ¢/kW h implies that, potentially, half the US energy production may come from solar by 205012 and comply with the European green deal roadmap.[13,14]. To utilize both heat energy and PV electricity from solar radiation, we may, for instance, look at the concept of solar thermal PV (STPV),[15,16] where the energetic tail of thermal emission is harvested by a low bandgap solar cell. Current PV/T techniques such as spectral splitting, where part of the solar spectrum is channeled to the PV cell while the other is channeled to a heat cycle, fall short because they sacrifice heat utilization for PV efficiency or vice versa
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