Solar Roof Tile: Transforming Residential Photovoltaic Systems in Qatar
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abstract
The state of Qatar, not only possesses a wealth of natural oil and gas, it is blessed by a high, relatively consistent, solar insolation exposure throughout the majority of the year, making solar photovoltaic (PV) a viable clean energy source to power the whole nation. Promoting the switch to renewable energy sources for domestic use will maintain Qatarâ s leadership role as a global energy exporter. This project addresses the challenges of implementing solar photovoltaic by proposing specially designed solar roof tiles for residential buildings in Qatar. Tackling the challenge with the shift towards renewable energy, in this proposal, begins with the residential buildings. Such effort, does not lay burden on the distribution company, Kahramaa, to invest into huge nation-wide infrastructure of solar farms. Instead, local generation of clean energy in the range of 5-10 kW reduces the reliance on carbon-based electric generation within residential neighborhoods, while not disrupting the operation of mechanical devices within the utility grid. A proposed solar roof tile, has the exact shape and material of the standard tile, but is coated with a photovoltaic layer with embedded energy conversion circuitry. The challenge with autonomous energy sources, particularly solar, is to harvest maximum available energy capacity, even with a stochastic and an unpredictable solar irradiance profile. Hence, the use of highly effective Maximum Power Point Tracking (MPPT) techniques, that ensure maximized harvest of the attainable solar irradiance energy from the PV system, becomes essential. The proposal of a solar roof tile raises structurally inherent flaws with the design - the curved morphology of the roof tile poses an inherent issue of self-shading. As such, shaded regions of the tile are only capable of capturing much lower energy compared to brighter regions of the roof tile. Classical MPPT techniques and traditional converter topologies are not well suited to tackle such issues of partial shading. The result is a roof tile that is limited to generating as much energy as its shaded region, which significantly drops the energy harvest of the whole roof configuration. The motivation for this project emerged from the NPRP Grant number 7-299-2-124 in which the partial shading problem was addressed by physically grouping PV strips on the roof tile according to their insolation and temperature. The resulting ideas and findings of the NPRP project were transformative, and have given rise to this PDRA proposal. This project considers a different approach to the partial shading challenge by locally equalizing the current at the cell level within the PV module.........
