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3 Questions with Nishikant ‘Nish’ Sonwalkar

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Nishikant “Nish” Sonwalkar, founder of SunDensity and inventor of the company’s trademarked photonic smart coating (PSC) technology, was named the top winner of the Luminate NY Finals in September 2020. The Luminate NY accelerator supports startups that offer optics, photonics, and imaging (OPI)-enabled technologies. As winner of Luminate NY’s third cohort, Sonwalker earned $1 million in funding for his company.

Unlike conventional antireflection coatings, SunDensity’s photonic smart coating decreases the levelized cost of energy (LCOE) by producing more power per panel. The coating can also be applied to digital imaging platforms such as night-vision cameras and CCDs — increasing digital camera responsivity — and to surfaces such as architectural windows to block heat in the summer and retain it during the winter.

Sonwalkar and SunDensity are currently targeting the development of a highly scalable manufacturing process. The company plans to open its own lab and release a line of pilot coatings in the next few months.


How do you quantify the effect that your photonic smart coating will have on the solar energy/solar power sector?

We quantify this effect in two ways: First, we do an optical characterization of the spectrum of white light before and after the coating to understand how much wavelength shift has occurred and how the shape of the spectrum has changed.

We next put coated glass on top of a solar cell and measure power output in terms of current and voltage (I-V characteristics) generated with and without the photonic smart coating. Our outdoor testing of two similar panels — one with PSC-coated glass and another identical reference panel without coating — indicated that a 22% efficiency solar cell reached 27% efficiency. This is a groundbreaking increase caused by the change in the photonics of the solar cell. The impact of efficiency gain provides more than a 20% increase in the power output. This leads to a significant reduction in the LCOE over the cell’s life cycle of 25 years. Any reduction in LCOE has a direct influence on the cost of energy generated by solar photovoltaic (PV) power systems. For a utility-scale power plant, for example, it is a significant potential improvement that will foster wider solar power adoption where the cost of solar energy is comparable or even less than the conventional gas-fired power plants. A development of over 580 GW of solar power enabled by PSC-coated solar panels will lead to the reduction of 2.9 gigatons of CO2 emission, which can have a significant effect on preventing climate change.

What is the mechanism by which your coating enables the conversion of blue light to red light?

We first trap the incoming photons using a photonic crystal structure created by the coating layers. We then shift the photons’ wavelengths by localized surface plasmon resonance layers created by the highly specialized nanoparticles embedded in the coating’s layers. Magnetron sputtering on glass substrates enables this highly scalable, high-precision, continuous process. Once the coating is applied on the inner side of the solar glass, the glass cover is glued on top of the solar cells to manage photons going into the solar cells.

We have filed patents on our innovative and highly efficient method, which enables downconversion of the high-energy (blue) photons to low-energy (red) photons that readily get absorbed in the bandgap of a PV solar cell. This process enables a quantum match between the energy of the incoming photons and the energy bandgap of a PV solar cell, leading to the generation of more electrons, thereby increasing the solar cell’s power output.

What do users need to know, and what must they do, to start using this coating on their panels?

Our users are power plants/utility-scale producers. The solar panel manufacturers supplying to the power plants do not need to change their production process; all they must do is to purchase the PSC-coated glass as cover for their solar panels. We partner with the glass companies to supply PSC-coated glass to the panel manufacturing companies. Again, we have chosen an industry-standard magnetron sputtering in-line coating process. Glass companies routinely use the process to apply antireflection coatings. As a result, we have also reduced barriers for our entry into the glass-coating market. Additionally, retrofitting is not required for new panels, as the PSC coating is embedded in the glass itself.

For existing and older panels, we have another product under design, which is a paper-thin glass with PSC coating. This coating can be laminated over the existing panel in a peel-and-stick method to improve the performance and power output. This will allow the SunDensity product line to reach residential, commercial, and utility-scale solar power plants to help usher in an era of clean energy that will be more commercially viable and able to compete with existing market prices and forces.

Photonics Spectra
Jan 2021
3 Questions

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