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We developed a system to estimate the photovoltaic (PV) potential of urban buildings using a 3D city model at level of detail 2 (LOD2), considering an arrangement of solar panels. Although the PV potential estimation of buildings at the level of city districts prefers LOD2 data, many urban city districts with buildings capable of installing solar panels on façades do not have LOD2 data owing to the high production cost of LOD2 data. Therefore, we investigated the possibility of utilising LOD1 data instead of LOD2 data in the PV potential estimation of buildings at the level of city districts. We conducted an experiment in the investigation using 3D city model data from 24 city districts, which are most of the large cities with LOD2 data in Japan. The experiment results suggest that LOD1 would not be a substitute for LOD2 data in the PV potential estimation of building roofs. The cause of the inadaptability is that most roofs in LOD2 buildings have more small polygons than LOD1 building roofs. Roofs of a LOD2 building with many small polygons have fewer solar panels than roofs of a LOD1 building with a large polygon. On the contrary, the experiment results indicate that LOD1 may be a substitute directly for LOD2 in the PV potential estimation of building façades that are expected to be used as a mounting platform for solar panels in urban buildings from now on. The average of the relative differences in the calculated PV potential of building façades between using LOD1 data and using LOD2 data is approximately 10% in the experiment. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) power generation is one of most promising means to prevent global warming in the present Japan. Since solar panels mounted on building façades are expected to come into wide use in urban areas, accurate estimation of PV potential of building façades is necessary for urban energy management planning. Accordingly, we have developed a system to estimate PV potential of urban buildings using a 3D city model. The system has two significant features: rapid estimation of hourly solar irradiance of points densely distributed on a building surface, and more flexible estimation of PV potential considering an arrangement of solar panels on a building surface. The paper reports our newly developed method to estimate PV potential of urban buildings considering an arrangement of solar panels using dense solar irradiance distribution on a building surface. The rapid estimation of dense solar irradiance distribution on a building surface enables the system to handle more flexible arrangement of solar panels with providing width and height of a solar panel, and clearance around solar panels. Considering some restrictions such as minimum solar irradiance of a solar panel makes PV potential estimated by the system become more realistic. The paper reports experiments conducted in seven urban districts in Japan to investigate the flexibility of the method by using various settings of panel installing conditions. Experiment results indicate that our developed method can estimate PV potential flexibly considering an arrangement of solar panels corresponding to various settings of panel installing conditions such as size of a solar panel. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) power generation is one of most promising means to prevent global warming in the present Japan. Since solar panels mounted on building façades are expected to come into wide use in urban areas, accurate estimation of PV potential of building façades is necessary for urban energy management planning. Accordingly, we decided to develop a system to estimate PV potential of urban buildings using a 3D city model. The system has two significant features: rapid estimation of hourly solar irradiance of points densely distributed on a building surface, and more flexible estimation of PV potential considering an arrangement of solar panels on a building surface. The paper reports our newly developed algorithm to estimate solar irradiance of urban buildings. The algorithm adopts the idea that "whether the sun can see us or not" indicates "whether we have sunshine or not" for calculation of hourly solar irradiance of a point on a building surface. In estimation of solar irradiance distributions on roofs and façades, utilization of projection images viewed from the sun created by using computer graphics (CG) techniques such as the depth buffer (Z-buffer) algorithm makes our system have much less computation time than most of existing systems using a hemispherical viewsheds or ray tracing. Results of an experiment conducted in Yokohama of Japan demonstrate that the algorithm would be able to estimate solar irradiance on not only roofs but also façades of urban buildings using a 3D city model accurately enough. [ABSTRACT FROM AUTHOR]

A 50-Gb/s optical receiver (RX) based on 0.18- $\mu \text{m}$ SiGe BiCMOS technology was fabricated and evaluated. To improve the horizontal eye opening and sensitivity of the RX without degrading its power efficiency, it is configured with a two-stage pre-amplifier with high gain (56 dB $\Omega $ ) and high bandwidth (35 GHz), a high-accuracy automatic decision-threshold control (ATC) consisting of power-supply variation and offset cancellers for improving sensitivity, and a jitter-reduction packaging structure for improving transimpedance flatness. The RX achieves high sensitivity of −9.2 dBm, while its power consumption is 7.9 pJ/bit at a data rate of 50 Gb/s. In 50- and 56-Gb/s transmission tests through a 100-m multi-mode fiber (MMF), it demonstrated error-free operation at the bit error rate (BER) of less than 10–12 with the sensitivities of −9 and −6.1 dBm optical modulation amplitude (OMA). It also demonstrated 300-m error-free MMF transmission (at 50 Gb/s) with the practical sensitivity of −7.6 dBm OMA. [ABSTRACT FROM AUTHOR]