NDJ Sustainable
Engineering,  LLC

BIPVT

We are working toward net-zero energy buildings through harvesting solar energy and improving energy efficiency of building envelope!

Building Integrated Photovoltaic Thermal System (BIPVT)

We are conducting intensive research and development to validate the manufacturing and integration method.

    Integration

    Although the original design of BIPVT panel includes four layers, i.e. photovoltaic (PV), thermoelectric (TE), functionally graded material (FGM), and fiber reinforced lightweight concrete (FRLWC) substrate layers, our recent performance tests have shown that the current TE technology cannot make the system cost effective. The panel without TE layer (BIPVT) provides much higher life cycle benefits than either a traditional panel without water cooling or the PVTET panel. Therefore, we will first transform this technology from the laboratory into the large scale production using the existing silicon PV modules on the market and the developed FGM manufacturing method. The design of the proposed BIPVT panel is shown in the figure, which is sized to integrate with industry standard structural framing spaced at 16" or 24" on center, but custom panels can easily be developed for longer spans. The prototype design references the International Building Code (IBC 2006) for roof assembly requirements for weather protection, such as flashings to prevent moisture penetrations at all roof interruptions and terminations. The proposed panelized system will employ a field-applied joint system. Gasketed design alternatives can also be developed. The following major components are included in the design:
  • The PV monocrystalline layer provides direct current production; polycrystalline and also a-Si thin films, CIGs thin films, and CdTe are alternative choices. All PV series array circuiting will be National Electric Code (NEC) compliant.
  • The FGM layer provides the polymer matrix for the closed water loop heat exchange system. Heat energy will be captured in the FGM layer and gathered with an insulated piping in the attic space.
  • The structural substrate provides the structural support for the BIPVT system so it can function as a roof deck and structural diaphragm for the building. A fiber reinforced lightweight concrete (FRLWC) panel will be used.

  • In addition, above the PV layer, a transparent protective layer functions as a water-proof membrane. A glass superstrate can be used in the current design. Our future exploration of the superstrate design will include the adoption of existing standard test procedures to promote acceptance of polymer superstrates, which are attractive due to their lightweight. The manufacture of this panel will not be more complex than the combination of traditional roof and PV panels. Once the FRLWC panel is successfully manufactured, the FGM layer can be cast through either the wet method or the dry method. At the beginning of the cure process, the FRLWC will be placed on the top of the mold contacting with the pure polymer. Applied vacuum and pressure will make the FRLWC perfectly glue on the FGM layer to form a whole piece of the panel. PV cells along with the protective layer will be glued on to the aluminum rich side of the panel through thermal conductive adhesive. The double serpentine connection alternatively aligns the water tubes with hot and cold temperatures keeping the panel surface temperature much more uniform.

    Once thermoelectric materials can be proven to be cost effective with an acceptable efficiency, say 4% of solar irradiation, the original design with four layers will provide a very promising solution to change the current PV market for high efficiency with low/medium cost PV cells. For example, CIGS PV cells may provide efficiency at about 16% for temperatures up to 85C. If 4% TE efficiency is achieved with a low cost QD-TE module, we may achieve an efficiency of 20%, which is achievable only by the very high cost multi-junction PV cells on the market.
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    integration