Test Results

3.1. Canadian Tests

The tests were performed over a two week period in October 2006 and the results are summarized in the following tables. Table 1 lists the two primary test conditions, #1 for NOCT test conditions typical of PV systems and #2 for test conditions typical of solar air collectors. The heat was drawn off at two rates, 36 and 108 m3/h. m2 (2 and 6 cfm/ft2) of collector surface and results are shown separately for each flow rate.

[2] Introduction

Hybrid Photovoltaic/Thermal (PV/T) collectors are devices that simultaneously convert solar energy into electricity and heat. The reason behind the concept of hybrid PV/T is only 6-15% (depending on the cell type and technology) of solar radiation converted into electricity by solar cell. The remaining energy is converted into heat which caused increased the solar cell temperature that will affect decreasing the solar cell efficiency. There are several reasons to combine Photovoltaic (PV) and Solar Thermal Collector into one PVT device which are larger overall conversion efficiency, reduced energy payback time, reduce economic payback time and improved aesthetics. Cooling the solar cell with working fluid like water and air will increase the solar cell efficiency. There are two ways to cool the PV/T, which are cooling by water and cooling by air. Cooling by water can be applied to produce hot water and cooling by air can be utilized for space heating application. Based on those facts, PV/T will be the ideal solution in the higher environmental temperature and also to keep long life the Solar Cell.

A Typical model of PV/T is the direct attachment of PV modules onto a solar collector surface. Per unit area the total efficiency of a PV/T panel is higher than the sum of the efficiencies of separate PV

[3] Rabl, A., (1985). Active Solar Collectors and Their Application, Oxford University. Press, Inc. New York

[4] Results and discussion

The results from HOMER show that for a load of 6000 kWh with a capacity shortage allowance of 10% and a hub height of 20 m not for all locations a feasible system is possible (Figure 3). For the load of 6000 kWh no feasible systems were found for the locations with the two highest latitudes. For loads of 3300 kWh and 1800kWh for all locations feasible systems were found. The NPC varies between $48,000 and $87,000 for the highest load and $17,000 and $33,000 for the lowest load. It is obvious that energy saving measures would a cost effective alternative instead of enlarging the system size.

[5] Introduction

The overall problem with the use of PV-systems is the high cost of the solar cells. This makes it appealing to concentrate irradiation on the PV module in order to minimise the required PV-area for the same output. With increased light concentration, there will be a demand of increased cooling on the PV cells in order to lower the working temperature preventing damages and maintaining cell efficiency. Solar8 is a photovoltaic/thermal parabolic concentrating system that tracks and concentrates light into a water cooled photovoltaic module working as a thermal absorber. By using the heat generated in the absorber, the photovoltaic/thermal device (PVT) generates not only electrical, but also thermal energy (Fig. 1). The photovoltaic module is formed by two sections, each one with 32 cells. These sections can be connected both in series and parallel. Generally, a concentrating system with a large number of series connected cells like Solar8 is highly sensitive of local defects in the optical system and on the solar cells, supposed to receive an equal amount of irradiation. The total electric

Добавить комментарий

Ваш e-mail не будет опубликован. Обязательные поля помечены *