Performance comparison of transparent solar windows to traditional windows – pv magazine International


Study results from the Wells Fargo Foundation and the NREL Initiative showed that photovoltaic coated windows can significantly reduce the coefficient of solar heat gain.

From pv magazine USA

In the IN2 Project NEXT, NEXT Energy Technologies photovoltaic coated windows were tested against traditional commercial windows, tracking performance based on their respective Solar Heat Gain Coefficient (SHGC), an industry standard performance measure for commercial windows. The results show that NEXT Energy’s technology could reduce the SHGC by an otherwise equal window of less than 0.20.

NEXT Energy is a California-based company that develops seamless energy harvesting window technology. The objective is to allow glazed facades to become producers of renewable energy on site and at low cost for buildings. NEXT Energy participated in a multi-year photovoltaic window project as part of the Wells Fargo Innovation Incubator (IN2), which measured the overall energy performance of NEXT Energy transparent photovoltaic windows compared to traditional commercial windows.

Commercial buildings account for 36% of total electricity consumption in the United States, at a cost of more than $190 billion per year. Additionally, windows account for 30% of a commercial building’s heating and cooling energy, costing U.S. building owners an estimated $50 billion a year, according to the DOE. Considering the potential savings, in addition to energy production, it is important to reduce the SHGC to 0.20. SHGC measures the amount of heat, or solar gain, created by sunlight passively entering buildings through windows. Excessive solar gain can lead to overheating in a space and inefficient energy management throughout the building.

“These are extremely significant results for the energy efficiency of insulating glazing. Achieving an SHGC of less than 0.20 while providing a neutral aesthetic has been a monumental challenge for all of us who create vacuum coated architectural glass. The balance between performance and appearance is at the heart of ideal harmony and it seems that NEXT has achieved this,” said Garret Henson, vice president of sales and marketing at Viracon, a manufacturer of architectural glass for commercial buildings. in North America.

In the manufacture of NEXT Energy’s windows, PV technology is enabled by proprietary organic semiconductor materials that are abundant in the earth and low cost, the company reports. This material is applied evenly to glass as an ink in a high-speed, low-cost, and energy-efficient process, allowing the glass to harvest sunlight and convert it to electricity rather than heat.

“The results of the collaboration with NEXT give us data on how to redefine the ways architects and building owners measure the performance of commercial windows,” said Trish Cozart, IN program manager.2 and Director of NREL’s Center for Innovation and Entrepreneurship. “If you can generate substantial amounts of electricity from a building’s windows, that can mark a new chapter. Now the focus is on the assessment of the SHGC to account for the impacts of power generation as well as solar heat gain.

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