A spectrally splitting photovoltaic-thermal hybrid receiver utilising direct absorption and wave interference light filtering

We have developed a novel spectrally splitting hybrid solar receiver by combining a simple dichroic filter and a liquid channel as a selective absorbing medium. The combination acts as a band pass filter for silicon solar cells. The geometry can be optimised for any linear concentrator; in this paper we have optimised it for a commercially available linear rooftop micro-concentrator. The optics of the concentrator at its focal region has been investigated using ray tracing. A simple 5-layer dichroic filter made of titanium dioxide and silicon dioxide has been designed, optimised, and fabricated with a focus placed on manufacturing simplicity. It has been shown that such a filter directs 54.5% of the concentrated light to the silicon photovoltaic cells; the Si cells considered in this paper can convert 26.1% of this energy into electricity which is significantly higher than their 20.6% efficiency under the full spectrum. This is due to the fact that 73.3% of the incident flux is within the cell's relatively high spectral response range, which can be efficiently converted into electricity. The rest of the spectrum can be collected as high temperature heat. This research shows the possibility of employing low-cost direct absorption-dichroic filtering hybrid receivers in liner concentrators.