We report on the design and installation of a spectrometer system for monitoring solar radiation in Cochabamba, Bolivia. Both the light intensity and the spectral distribution affect the power produced by a photovoltaic device. Local variations in the solar spectrum (especially compared to the AM1.5 standard) may have important implications for device optimization and energy yield estimation. The spectrometer system, based on an Ocean Optics USB4000 (300-900nm) spectrometer, was designed to increase functionality. Typically systems only record the global horizontal radiation. Our system moves a fiber-optic cable 0-90 degrees and takes measurements in 9 degree increments. Additionally, a shadow band allows measurement of the diffuse component of the radiation at each position. The electronic controls utilize an Arduino UNO microcontroller to synchronizes the movement of two PAP bipolar (stepper) motors with the activation of the spectrometer via an external trigger. The spectrometer was factory calibrated for wavelength and calibrated for absolute irradiance using a Sellarnet SL1-Cal light source. We present preliminary results from data taken March-June, 2013, and comment on implications for PV devices in Cochabamba.
This article reports the construction of a portable, low-cost LIBS (Light Induced Breakdown Spectroscopy) system for use in the Bolivian mining industry for the qualitative and quantitative analysis of the composition of mineral samples. The device consists of a portable laser, a medium-resolution spectrometer and an optomechanical light collection system. The laser developed for the device is a YAG:Nd+++ with an estimated power output of 10 MW/cm2. Weighing approximately 3 kg and powered by lithium ion batteries, it is easily carried and can be used in remote locations. The spectrometer has a resolution of 0.3 nm allowing the detection fine spectral features, while its range of 80 nm is broad enough to simultaneously show many of the principal spectral lines of the element of interest. A monochromatic CCD camera was used as the detector of the spectrometer and was fitted with an external trigger to coordinate the camera frames with the firing of the laser. The light emitted by the plasma is collected with a photographic objective and is transmitted to the spectrometer via a fiber optics cable. A mechanical system was incorporated to make, both the laser beam and the receptor positionable. In the preliminary tests of the prototype, a LIBS spectrum of a Bolivian copper coin was obtained. Analysis showed that the spectral lines obtained coincide with those of a copper reference spectrum and demonstrate the capacity of the device to perform qualitative analysis of materials.