Multi-element lenslet array for efficient solar collection at extreme angles of incidence

Abstract

Photovoltaics (PV) are a versatile and compact route to harness solar power. One critical challenge with current PV is preserving the optimal panel orientation angle with respect to the sun for efficient energy conversion. We experimentally demonstrate a bespoke multi-element lenslet array that allows for an increased power collection over a wide field of view by increasing the effective optical interaction length by up to 13 times specifically at large angles of incidence. This design can potentially be retrofitted onto already deployed amorphous silicon solar panels to yield an increased daily power generation by a factor of 1.36 for solar equivalent illumination. We 3D printed an optical proof of concept multi-element lenslet array to confirm an increase in power density for optical rays incident between 40 and 80 degrees. Our design indicates a novel optical approach that could potentially enable increased efficient solar collection in extreme operating conditions such as on the body of planes or the side of buildings.

Multi-layer light trapping structures for enhanced solar collection

“…The non-planar optical surface can further reduce reflective losses on the edges of the first array lenses for light incident at particular angles. Such arrangement resolves some of the reflective losses of the previously presented MELA design [19], while providing a similar angular diffusion of light at higher incident angles. Our simulation indicate that this design is particularly useful for near-normal incidence deployment and can be employed for case-specific applications where the solar alignment is predefined or guaranteed, such as tracking-integrated systems.…”

“…This efficiency sweep was performed by varying the absorption factor that defines the conversion efficiency for a single normal light bounce within the absorber layer and subsequently compute the increase in optical power that can be absorbed for rays with power density equivalent to or greater than 1 mW/m 2 . These efficiency ranges were determined to encompass the minimum average efficiency for commercial devices (see [29] for crystalline silicon and supplementary material in [19] for amorphous silicon) and the theoretical efficiency limit for each silicon technology (see [30] for crystalline silicon and [31] for amorphous silicon). Both results predict that the optical gain decreases as the panel efficiency increases.…”

“…Multi-element optical devices are revolutionising the way we control light for many photonics technologies and can be tailored to transform the trajectories of light in a bespoke manner. Recent advances have demonstrated the use of such multi-element optics in the form of a lenslet array for efficient solar collection at extreme angle of incidences [19]. These systems can be a compound of multiple optical elements or the combination of optics with novel materials to achieve multi-layer unconventional control of light.…”

“…The multi-layer lenslet array approach is adopted from recent work outlining a design of two arrays of hemispheric lenses that are bonded together with their curved faces, to be used on top of solar cells to promote light trapping at extreme angles and enable their use in non-tracking deployments. These optical elements build on our previously reported MELA arrangement to produce a wide field of view (±80°) that allows efficient coupling for normally incident light with increased efficiency for rays incidents at high angles of incidence [19]. This previously reported MELA design focused on solar cells with no integrated light trapping structures, limiting the designs compatibility for a broad range of commercially deployed solar panels.…”

Microlenses arrays: Fabrication, materials, and applications

“…Peer et al employed light interaction with a periodically structured MLA to enhance absorption in solar cells and enhanced light emission in OLEDs (Peer, Biswas, Park, Shinar, & Shinar, 2017). Alsaigh and co‐workers put multi‐element lenslet array on solar photovoltaic (PV) surfaces to improve solar conversion efficiency from 4.6% to over 8% (Alsaigh, Bauer, & Lavery, 2020).…”