NYPA Headquarters Second Solar PV System

A second solar PV system was installed on the roof of NYPA Headquarter building located at 123 Main Street, White Plains, on August 26, 2008.  The system is comprised of two 4kW subsystems; one made of Kaneka’s thin film amorphous silicon cells and the other of Sharp’s polycrystalline silicon cells.  The objective of the installation is to compare the performance between the thin film solar cells and conventional polycrystalline solar cells.  This installation is in addition to the existing 5.5kW system installed in 1997. 

It is estimated that the system is going to generate about 8,400kWh electricity per year with a total savings of $1260 and corresponding CO2 emission reductions of 5.418 short ton.    

Cheap, durable, and efficient devices are needed to generate a significant amount of electricity from the sun.  Thin film solar cells use a fine layer of semiconducting material, such as silicon, copper indium gallium selenide (CIGS) or cadmium telluride, deposited onto a substrate to harvest electricity from sunlight at a fraction of the cost compared to conventional photovoltaic cells.  The cost savings are realized primarily due to reduced material needs, lower manufacturing energy requirements and broader suitability to mass production. 

The substrate material could be glass, flexible metallic foils, high-temperature polymers or stainless steel sheets.  Due to the flexibility with the substrate materials and its lightweight characteristics, thin film solar cells are suitable in special architectural uses, such as photovoltaic roof shingles, windows, siding and others (so-called Building Integrated Photovoltaics).  Thin film cells also have the potential to produce more power over time than the older technology, because they resist the sun’s heat better and produce more power when the temperature spikes.

Despite its lower cost and broader market applications, thin film solar cell does have its challenges.  The first challenge is the lower energy conversion efficiency.  Lower manufacturing temperature affects the crystal formation.  The amorphous silicon has dangling and twisted molecular bonds, which results in more interrupted electron flow and correspondingly lower energy conversion efficiency.  The second challenge is high land/area usage resulted from lower energy conversion efficiency.  More panels are needed for thin film cells in order to achieve the same amount of power output.  Another challenge is the reliability.  The lifetime of the device still remains to be seen.              

For this demonstration project, Kaneka’s thin film solar panels have amorphous silicon deposited on the glass substrate and have rigid frame.  They were installed side by side with Sharp’s polycrystalline solar panels.  Sun irradiance and panel temperatures will be monitored in-situ, as well as system energy generation data.  We will confirm the benefits and challenges that both technologies are facing.   

Manufacturer: Kaneka for Thin Film and Sharp for Polycrystalline

Solar Technology: Amorphous Silicon and Polycrystalline Silicon

No. of Modules: 68 and 24

PCU: Fronius 4500 LV, 208Vac for both systems