Techno-economic feasibility of grid-independent residential roof-top solar PV systems in Muscat, Oman

Oman is a country characterised by high solar availability, yet very little electricity is produced using solar energy. As the residential sector is the largest consumer of electricity in Oman, we develop a novel approach, using houses in Muscat as a case study, to assess the potential of implementing roof-top solar PV/battery technologies, that operate without recourse to the electricity grid. Such systems target the complete decarbonisation of electricity demand per household and are defined in this study as grid-independent systems. The approach adopted starts with a technical assessment of grid-independent systems that evaluates the characteristics of the solar panel and the battery facility required to provide grid-independence. This is then compared to a similar grid-connected system and any techno-economic targets necessary to enhance the feasibility of residential roof-top PV systems in Muscat are identified. Such an analysis was achieved through developing a detailed techno-economic mathematical model describing four sub-systems; the solar panel DC source, the grid-independent sub-system, the grid-connected sub-system and the economic sub-system. The model was implemented in gPROMS and uses real hourly weather and climate conditions matched with real demand data, over a simulated period of 20 years. The results indicate that, in the context of the system studied, grid-independent PV systems are not feasible. However, combined with a sufficiently high electricity price, grid-independent systems can become economically feasible only with significant reductions in battery costs (>90% reductions)

Free vibrations of a plate with varying number of supports

This experimental investigation tested the accuracy of an analysis which predicts the natural frequencies of vibration of a plate constrained by an arbitrary number of point supports along the edges, and also determined the number of such supports which approximates an infinite number

Redshift Determination and CO Line Excitation Modeling for the Multiply Lensed Galaxy HLSW-01

We report on the redshift measurement and CO line excitation of HERMES J105751.1+573027 (HLSW-01), a strongly lensed submillimeter galaxy discovered in Herschel/SPIRE observations as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). HLSW-01 is an ultra-luminous galaxy with an intrinsic far-infrared luminosity of L _(FIR) = 1.4 × 10^(13) L _⊙, and is lensed by a massive group of galaxies into at least four images with a total magnification of μ = 10.9 ± 0.7. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify a redshift of z = 2.958 ± 0.007 for this source, using the simultaneous detection of four CO emission lines (J = 7 → 6, J = 8 → 7, J = 9 → 8, and J = 10 → 9). Combining the measured line fluxes for these high-J transitions with the J = 1 → 0, J = 3 → 2, and J = 5 → 4 line fluxes measured with the Green Bank Telescope, the Combined Array for Research in Millimeter Astronomy, and the Plateau de Bure Interferometer, respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full CO spectral line energy distribution is described well by warm, moderate-density gas with T _(kin) = 86-235 K and n_H_2 = (1.1-3.5)x10^3 cm^(–3). However, it is possible that the highest-J transitions are tracing a small fraction of very dense gas in molecular cloud cores, and two-component models that include a warm/dense molecular gas phase with T _(kin) ~ 200 K, n_H_2 ~ 10^5 cm^(–3) are also consistent with these data. Higher signal-to-noise measurements of the J _(up) ≥ 7 transitions with high spectral resolution, combined with high spatial resolution CO maps, are needed to improve our understanding of the gas excitation, morphology, and dynamics of this interesting high-redshift galaxy