A solar electrical vehicle is an electric car power-driven by solar panels attached to the vehicle, typically the cars roof. These photovoltaic cells (PV) transform the sun's intensity into electric power and change sunlight into electricity to drive the electric motors. The energy produced by the sun can be utilized to supply energy for all or part of a car's movement, or additional secondary tasks. Solar vehicles have instruments to notifying drivers of energy supply and potential problems. Most solar cars are limited by the amount of energy generated for the vehicle because of their design.

Abstract

Solar Electrical Vehicles-The major automobile manufacturers are producing hybrid automobiles, which are part electric and part gasoline powered. Could these automobiles take another step and obtain some of their fuel from the sun? Solar Electrical Vehicles has developed a prototype PV Prius to help answer that question.

The PV Prius is fitted with a custom molded fiberglass photovoltaic module as shown in Figure 1. Solar Electrical Vehicles has applied for a patent on the PV Prius solar system.

The photovoltaic module is rated at 215 watts at AM 1.5. The module is connected to a DC-DC converter and peak power tracker. The output of the converter is directly connected to the primary motive NiMh battery.

The daily power production available for charging the Prius primary motive battery is estimated to be between 850 and 1,300 watt-hours. The car uses 150-175 watt-hours per mile. Thus, the expected range per day that the PV Prius would have on solar power alone would be between 5 and 8 miles. Based upon a nominal daily trip length of 28 miles the gasoline consumption of the PV Prius would be reduced by 17% to 29%.

Description of Solar Module

The solar module is fabricated from molded fiberglass to fit on the roof of a standard Toyota Prius automobile. The solar module includes 146 four-inch- square mono-crystalline cells which are rated at 16% nominal efficiency. The cells generate 3.5 A short circuit and 0.57 VDC open circuit. Using a series connection, the PV Cells, which produce 80 VDC, open circuit, 70 VDC at the peak power point with a string current of 3.25 amperes at AM 1.5 conditions.

Figure 1. Photo of the Prototype PV Prius

An insulating layer of Tedlar is bonded to the fiberglass with a heat-cure adhesive. The solar cells are series connected and then bonded to the Tedlar insulation with EVA encapsulant. Finally, a Tefzel layer is bonded to the top of the cells for ultraviolet and weather protection. Figure 2 provides a diagram showing the individual layers of the solar module.

Figure 2. Solar Module Component Layers