Solid-State Solar Simulator

This paper presents an efficient, low-cost, and versatile LED-based solar simulator intended to produce a well-characterized spectrum for tests of solar cells and other photosensitive devices. Three major design aspects are addressed: LED spectra, power converters for LED drive, and control. The visible light of a standard solar spectrum is simulated using six LED colors. The number of LEDs and their placement for uniformity are addressed. Boost converters under current-mode control are used to achieve reproducible LED brightness through adjustable currents, or equivalent radiant-flux commands. The independent control of the six colors can simulate a range of different light sources and solar spectra. Uniformity tests verify that the system achieves standard spectral uniformity requirements over an area of 100 mm × 100 mm in simulations and 100 mm × 50 mm in experiments. LEDs in the proposed simulator consume less power and reduce the simulator size compared to the available state of the art. The user-friendly interface also allows active control of the simulated spectrum.

I. Introduction

Light-Spectrum simulation is a challenging power-electronics application that demands accuracy and thorough consideration of light characteristics. Most of the literature on light simulation has focused on simulating sunlight for photovoltaic (PV) testing, e.g., [1]–[3]. Sunlight simulation is also used to treat seasonal affective disorder and to support research on photosynthetic organisms. Other applications include fluorescence analysis in biological applications, color-temperature calibration for camera equipment, and color-rendition accuracy testing. This paper focuses on the design and implementation of a solar simulator where the target is to match the visible portion of the standard air mass (AM) 1.5 global (AM1.5G) solar spectrum [4]. The design of the LED platform, in addition to the power electronics and control, establishes a missing link in the literature, where these aspects are usually treated independently. Efficient solid-state LED lighting avoids inefficient halogen, xenon, and sodium lamps. Compared to the state of the art, utilizing LEDs simplifies thermal management and creates a compact low-cost system. The power-electronics topology and current-mode control, shown in Fig. 1, along with a user-friendly GUI achieve flexibility to control the desired output spectrum. This GUI is not usually considered in state-of-the-art solar simulators even though it provides a user-friendly interface to actively simulate different spectra. Radiant-flux control can be used to simulate solar spectra at different times of day, in addition to other light sources. Fig. 1.

Proposed LED-array configuration, where is the number of LEDs per string and is the number of strings or colors.