Solar Photovoltaic Architecture and Agronomic Management in Agrivoltaic System: A Review

Agrivoltaic systems (AVS) offer a symbiotic strategy for co-location sustainable renewable energy and agricultural production. This is particularly important in densely populated developing and developed countries, where renewable energy development is becoming more important; however, profitable farmland must be preserved. As emphasized in the Food-Energy-Water (FEW) nexus, AVS advancements should not only focus on energy management, but also agronomic management (crop and water management). Thus, we critically review the important factors that influence the decision of energy management (solar PV architecture) and agronomic management in AV systems. The outcomes show that solar PV architecture and agronomic management advancements are reliant on (1) solar radiation qualities in term of light intensity and photosynthetically activate radiation (PAR), (2) AVS categories such as energy-centric, agricultural-centric, and agricultural-energy-centric, and (3) shareholder perspective (especially farmers). Next, several adjustments for crop selection and management are needed due to light limitation, microclimate condition beneath the solar structure, and solar structure constraints. More importantly, a systematic irrigation system is required to prevent damage to the solar panel structure. To summarize, AVS advancements should be carefully planned to ensure the goals of reducing reliance on non-renewable sources, mitigating global warming effects, and meeting the FEW initiatives.

Performance of wide band gap amorphous silicon alloys as passivation layer in graded band gap solar structure

This work investigates the behaviour of two amorphous silicon wide band gap alloys: amorphous silicon nitride (aSiN x ) and hydrogenated amorphous silicon carbide (aSi x C 1-x :H) as passivation layer in previously designed band gap tailored single junction photovoltaic structure: p + aSi x C 1-x :H/i-aSi:H/n + aSi 1-x Ge x :H. The work involves fabrication of PECVD made aSiN x samples followed by detailed optical characterisation on band gap tailoring interms of mole fraction,x. A rigorous study is made on the current density-voltage (J-V) characteristics as well as on the Internal Quantum Efficiency (IQE) characteristics of the recommended band gap tailored solar structure using aSiN x and aSi x C 1-x :H as passivation layers. The progressive band gap tailored solar cell structure using aSi x C 1-x :H passivation layer accomplishes conversion efficiency of 15.59 % while similar structure having aSiN x passivation layer delivers an efficiency of 15.32 %. By virtue of the obtained results, it is observed that aSi x C 1-x :H with high carbon content is more efficient than aSiN x to be considered as passivation layer. The work presents the performance of continuously band gap graded amorphous silicon alloy as passivation layer in single junction photovoltaic structures for the first time.

Updated solar neutrino fluxes with new heavy element abundances

In the present work we carry out an extensive study of the solar structure and solar evolution through the use of the TYCHO 6.92 code, which includes a variety of programs and subroutines. In this code we incorporate the most updated microphysical parameters such as screening, recent experimental measurements of the astrophysical factors-S (LUNA), several updated, recently measured, heavy element abundances, etc., and created new models describing crucial phenomena of the solar structure and solar evolution. We used this code to calculate and update nuclear reaction rates, solar neutrino fluxes, solar quantities which characterize the internal solar structure such as temperature, pressure, density, luminosity, heavy element abundances (4He, 12C, 14N, 16O, etc.) as well as sound speed profile and depth of the convection zone.

Signature of solar g modes in first-order p-mode frequency shifts

Context. Solar gravity modes (g modes) are buoyancy waves that are trapped in the solar radiative zone and have been very difficult to detect at the surface. Solar g modes would complement solar pressure modes (p modes) in probing the central regions of the Sun, for example the rotation rate of the core. Aims. A detection of g modes using changes in the large frequency separation of p modes has recently been reported. However, it is unclear how p and g modes interact. The aim of this study is to evaluate to what extent g modes can perturb the frequencies of p modes. Methods. We computed the first-order perturbation to global p-mode frequencies due to a flow field and perturbations to solar structure (e.g. density and sound speed) caused by a g mode. We focused on long-period g modes and assumed that the g-mode perturbations are constant in time. The surface amplitude of g modes is assumed to be 1 mm s−1, which is close to the observational limit set by Doppler observations. Results. Gravity modes do perturb p-mode frequencies to first order if the harmonic degree of the g mode is even and if its azimuthal order is zero. The effect is extremely small. For dipole and quadrupole p modes, all frequency shifts are smaller than 0.1 nHz, or 2 × 10−8 in relative numbers. This is because the relative perturbation to solar structure quantities caused by a g mode of realistic amplitude is of the order of 10−6–10−5. Additionally, we find that structural changes dominate over advection. Surprisingly, the interaction of g and p modes takes place to a large part near the surface, where p modes spend most of their propagation times and g modes generate the largest relative changes to solar structure. This is due to the steep density stratification, which compensates the evanescent behaviour of g modes in the convection zone. Conclusions. It appears to be impossible to detect g modes solely through their signature in p-mode frequency shifts. Whether g modes leave a detectable signature in p-mode travel times under a given observational setup remains an open question.