Development and experimental evaluation of a complete solar thermophotovoltaic system

We present a practical implementation of a solar thermophotovoltaic (TPV) system. The system presented in this paper comprises a sunlight concentrator system, a cylindrical cup-shaped absorber/emitter (made of tungsten coated with HfO2), and an hexagonal-shaped water-cooled TPV generator comprising 24 germanium TPV cells, which is surrounding the cylindrical absorber/emitter. This paper focuses on the development of shingled TPV cell arrays, the characterization of the sunlight concentrator system, the estimation of the temperature achieved by the cylindrical emitters operated under concentrated sunlight, and the evaluation of the full system performance under real outdoor irradiance conditions. From the system characterization, we have measured short-circuit current densities up to 0.95 A/cm2, electric power densities of 67 mW/cm2, and a global conversion efficiency of about 0.8%. To our knowledge, this is the first overall solar-to-electricity efficiency reported for a complete solar thermophotovoltaic system. The very low efficiency is mainly due to the overheating of the cells (up to 120 °C) and to the high optical concentrator losses, which prevent the achievement of the optimum emitter temperature. The loss analysis shows that by improving both aspects, efficiencies above 5% could be achievable in the very short term and efficiencies above 10% could be achieved with further improvements

Attraction of <i>T. dimidiata</i> by light of different wavelength.

<p>(A) Light emitting diodes (LEDs) of the indicated wavelength were used in the dual choice chamber and attraction measured for adult male and female triatomines. (B) Triatomines were also given the choice between white and yellow light. *, **, and *** indicate a significant difference with the control without lights (<i>P</i><0.05, <0.01 and <0.001, respectively) and numbers in parenthesis indicate the number of triatomines tested.</p

Activity pattern and light attraction of <i>T. dimidiata</i> during the night.

<p>(A) The number of individual movements per hour was determined from the analysis of the video recordings of adult males, females and 5^th stage nymphs. (B) The time adult males (dark gray bar) and females (white bar) entered the tunnel with light was recorded. Shaded gray areas indicate the night period.</p

Observed distance from houses to the nearest light according to their infestation status.

<p>(A) Distance to the nearest peridomicile light of infested (black bars) and non-infested houses (light gray bars). (B) Distance to the nearest public street light of infested and non-infested houses. Data are presented as mean ± SEM. *, **, and *** indicate a significant difference between infested and non-infested houses (<i>P</i><0.05, <0.01 and <0.001, respectively).</p

Spatial patterns of infestation and artificial lights.

<p>(A) Examples of spatial distribution of infested (red circles) and non-infested houses (empty squares) and public street lights (yellow circles) from parts of the indicated villages. (B) Examples of spatial distribution of infested and non-infested houses and peridomicile lights (yellow squares) in the indicated villages. Lines represent the streets. Scale bars: 50 m.</p

Relationship between infestation and the proximity of street lights.

<p>The proximity of a public street light resulted in a 1.64 fold increase in the likelihood of a house being infested (95% confidence interval: 1.23–2.18).</p

Attraction of <i>T. dimidiata</i> by white light in a dual-choice chamber.

<p>(A) Screen capture image of the chamber showing a triatomine about to enter the lit tunnel (arrow). (B) Attraction by light of adult male and female and 5^th nymphal stage triatomines. The attraction index was calculated as described in the methods, with positive values indicating preference for the lit tunnel, negative values for the dark tunnel, and 0 indicates random distribution in both tunnels. Control experiments were carried out with both tunnels in the dark. *** indicates a significant difference with the control without lights (<i>P</i><0.001) and numbers in parenthesis indicate the number of triatomines tested.</p

Key eco-bio-social determinants for house infestation by non-domiciliated <i>Triatoma dimidiata</i>.

#<p>indicates the most important variables in the averaged model and</p>*<p>indicates a statistically significant odds ratio of variables when considered individually.</p

Typical housing and peridomestic structures in rural Yucatan, Mexico.

<p>Typical housing and peridomestic structures in rural Yucatan, Mexico.</p

Comparison of predicted infestation probability and observed infestation in groups of 20 houses based on the averaged model.

<p>Houses were divided into 15 groups based on their predicted individual probability of infestation and their mean probability of infestation was compared with the observed infestation index for each group. The relationship was: Predicted infestation = 0.032+0.878*Observed infestation (R² = 0.85, <i>P</i><0.0001).</p