Experimental Study And Performance Optimization Of The Linear Flat Mirror Concentrator

Concentrating photovoltaics (CPV) technology, which is considered to have agreat potential for efficiency improvement and cost reduction in solar powergeneration, has been showing a fast growing trend in recent decades. Concentrator isan important part of the CPV system, since its focal spot directly affects the workingenvironment of the concentrator solar cells. Aiming at overcoming the problems ofexisting concentrators, a low-cost Linear Flat Mirror Concentrator (LFMC) wasproposed and the optimization was studied in this thesis.In order to guide the design and utilization in the CPV system of the LFMC, theoptical performance of the LFMC with specific design parameters at typical incidenceangles was simulated using software TracePro and Solidworks. Its concentration ratio,uniformity of the focal spot, spot width and shade between adjacent mirrors wasstudied. There is no shade between adjacent mirrors when the incidence angle is lessthan the limit incidence angle, and the flux density distribution is uniform in the80mm wide effective focal spot, around16kW/m2. Otherwise, the shades emerge.The LFMC with same design parameters as the model was designed anddeveloped. The flux density distribution of the focal spot at typical incidence angleswas tested and calibrated with the indirect measurement method in the principle of theCCD (Charge Coupled Device) imaging. To a great degree, the flux density dependson the DNI. The flux density values divided by the DNI at the corresponding moment,we can get the tested concentration ratio of the concentrator. The tested concentrationratio reaches the highest value when light is at the normal incidence, and the averageis14.63. When the light is at0°or±15°incidence angle, the optical simulation can bea good characterization of the concentrator performance, while the relative error of thesimulated and tested values is below5%.The minimum distance formula between mirrors without shading at limit incidentangle is derived, and the mathematical modeling is programmed based on this formula,and every design parameter is analyzed and optimized. The results show that, theimpact of the mirror number and mirror width on the size and performance of theLFMC is relatively small. The limit incident angle and the height of receiver have alarge impact on its concentrating performance, and the limit incident angle alsoconstraints the running time and the size of the concentrator system. Using the backcontact crystalline silicon solar module from SunPower as the receiver, we do the optimization and optical simulation about the concentrator. The simulation resultsshow that the light intensity distribution on the cell is even, the average irradiance isaround15.5kW/m~2and the system generated output is up to2.65kW.