Crystalline silicon cell performance at low light intensities

Abstract

Measured and modelled JV characteristics of crystalline silicon cells below one sun intensity have been investigated. First, the JV characteristics were measured between 3 and 1000 W/m 2 at 6 light levels for 41 industrially produced mono-and multi-crystalline cells from 8 manufacturers, and at 29 intensity levels for a single multi-crystalline silicon between 0.01 and 1000 W/m 2. Based on this experimental data, the accuracy of the following four modelling approaches was evaluated: (1) empirical fill factor expressions, (2) a purely empirical function, (3) the one-diode model and (4) the two-diode model. Results show that the fill factor expressions and the empirical function fail at low light intensities, but a new empirical equation that gives accurate fits could be derived. The accuracy of both diode models are very high. However, the accuracy depends considerably on the used diode model parameter sets. While comparing different methods to determine diode model parameter sets, the two-diode model is found to be preferred in principle: particularly its capability in accurately modelling V OC and efficiency with one and the same parameter set makes the two-diode model superior. The simulated energy yields of the 41 commercial cells as a function of irradiance intensity suggest unbiased shunt resistances larger than about 10 kO cm 2 may help to avoid low energy yields of cells used under predominantly low light intensities. Such cells with diode currents not larger than about 10 À9 A/cm 2 are excellent candidates for Product Integrated PV (PIPV) appliances.

Performance of Photovoltaics Under Actual Operating Conditions

“…Other investigations have further demonstrated that series resistance losses are mainly responsible for the reduction in the FF for intensities of 60 % of one sun or greater (del Cueto, 1998). Both mono-c-Si and multi-c-Si technologies exhibit almost constant efficiencies in the irradiance range of 100 -1000 W/m 2 with mono-c-Si found to outperform multi-c-Si in an investigation performed on commercial PV cells (Reich et al, 2009). In addition, some c-Si cells were found to have higher efficiencies at irradiance intensities in the range 100 -1000 W/m 2 than at STC and this is attributed to series resistance effects, as a lower current leads to quadratically lower series resistance loss (Reich et al, 2009 (Mohring & Stellbogen, 2008).…”

“…These offer the advantage that other effects such as AOI, spectrum and temperature can be controlled and excluded from the investigation. A common approach used is the acquisition of the current-voltage (I-V) curves at the cell or module level using solar flash simulators, which allow the evaluation and comparison of the efficiency at different specified irradiance levels indoors (Bunea et al, 2006;Reich et al, 2009). Similarly, the effects of solar irradiance have been investigated in outdoor evaluations by first acquiring I-V curves at again cell or module level and secondly correcting the acquired data-sets to STC temperature, by using measured or manufacturer temperature coefficients (Merten & Andreu, 1998;Paretta et al, 1998).…”

“…Both mono-c-Si and multi-c-Si technologies exhibit almost constant efficiencies in the irradiance range of 100 -1000 W/m 2 with mono-c-Si found to outperform multi-c-Si in an investigation performed on commercial PV cells (Reich et al, 2009). In addition, some c-Si cells were found to have higher efficiencies at irradiance intensities in the range 100 -1000 W/m 2 than at STC and this is attributed to series resistance effects, as a lower current leads to quadratically lower series resistance loss (Reich et al, 2009 (Mohring & Stellbogen, 2008). Furthermore, CdTe thin-film technology has been reported as having a relatively good low irradiance performance (Heesen et al, 2010;) and specifically to exhibit significant performance increase at medium irradiance levels due to the relatively high series resistance of CdTe devices (Mohring & Stellbogen, 2008).…”

State-of-the-art review of solar design tools and methods for assessing daylighting and solar potential for building-integrated photovoltaics

“…Many researches has been carried out to investigate the behaviour of the PV cells under low light conditions, such as for c-Si [192], a-Si and CIGS [193] and other cell materials [194] [195] [196]. Stamenic et al demonstrated the influence of low light conditions in the simulation of (BIPV) systems [197].…”

A Proposal for Typical Artificial Light Sources for the Characterization of Indoor Photovoltaic Applications

“…Indeed, because our goal is to determine which light sources are relevant for a possible new standard for the indoor characterization of solar cells, it is the spectrum of the light sources that distinguishes the light sources, and not the low intensity, which is present for all light sources and will affect the cells equally over all light sources. We refer to [10,[49][50][51][52][53] for details of the influence of low intensity on the characteristics of different types of solar cells. Moreover, we also considered all suitable artificial indoor light sources and selected relevant ones which could be utilized as a standard for the indoor characterization.…”