Quantifying net energy metering subsidies

Net energy metering (NEM) is the policy available in many states that promotes customer-owned rooftop solar power generation by compensating rooftop solar owners for each kWh that it generates at the retail rates. To help understand the magnitude of the residential net metering subsidies, we conducted a study to assess the subsidies for 16 US utilities with varying geographic location, size, rooftop solar penetration, and NEM policy.     

Current drive methods to extend the range of travel ofelectrostatic microactuators beyond the voltage pull-in point

When a voltage source drives an electrostatic parallel plate actuator, the well-known pull-in instability limits the range of displacement to 1/3 of the gap. Different strategies have been reported to overcome this limitation. More recently, experimental results have been presented using a capacitor in series with the actuator. Nevertheless, this strategy requires higher voltage than the pull-in voltage value to achieve full range of travel. In order to reduce the operating voltage, a switched-capacitor configuration has been also proposed. In this paper, two different approaches are introduced to control charge in the actuator by means of current driving. Theoretical equations derived for each method show that full range of travel can be achieved without voltage penalty. Both approaches are based on the use of current pulses injecting the required amount of charge to fix the position of the movable plate. Experimental measurements, showing that displacement beyond the pull-in point can be achieved, are in good agreement with the theoretical and the predicted simulated behavior     

Radiation damage evaluation on AlGaAs/GaAs solar cells

A computer model to evaluate radiation damage on AlGaAs-based solar cells is reported. The model is based on a piecewise approach that divides the cell structure in an adaptive number of slices. Inside a particular slice the semiconductor parameters are constant; consequently, it is easy to find an analytical solution of the semiconductor transport equations with suitable boundary conditions for the interfaces with the adjacent slices. The model provides all electrical parameters of the cells in the operating temperature range. Different structures, including graded band gaps and double heterofaces can be analyzed. Proton damage coefficients as well as proton damage ratios can be calculated for energies between 30 and 10⁴ keV with only two adjustable parameters. Coirradiation experiments with different energy protons were simulated by improving the conventional method of degradation computering     

Effects of rapid thermal processing on the current gain and emitterresistance of polysilicon emitter bipolar transistors

Results of measurements of base current and emitter resistance of polysilicon emitter transistors subjected to different rapid thermal anneal processes of the interfacial layer and different emitter drive-in times are presented. It is shown that a rapid thermal anneal for temperatures on the order of 1050°C leads to devices in which the base current is essentially independent of the emitter drive-in time. The emitter resistance obtained in devices given this interface anneal is considerably lower than that in devices without the anneal, and hence the values obtained are compatible with the requirements for realizing submicrometer bipolar circuits     

Low-cost thermal /spl Sigma/-/spl Delta/ air flow sensor

This paper describes the design and optimization of a hot-wire air flowmeter. A low-cost design of the packaging allows good thermal contact with the airflow, as well as good thermal isolation between the hot and cold points. It is a compact solution which allows easy PCB mounting and adaptation to standard-size small air pipes. The design has been optimized for low-cost applications. The sensor is read out by a thermal sigma-delta modulator. The dynamic range of this modulator has been extended by adding a constant power offset to its output. The fractal nature of the modulator response at low-clock frequencies is also experimentally shown.     

Multichip module photovoltaic miniarrays

In this work a novel concept of photovoltaic mini array assembly is described based on a flip-chip multichip module technology. A number of arrays composed of 15 series-connected 2 mm² c-Si photovoltaic cells have been fabricated, achieving a packaging density of 40 cells/cm². Measurements of the dark I-V characteristic confirmed that the resistive losses of the approach are small and do not degrade the electrical characteristics of the array. Nearly 0.5 mW/cm ² delivered density power, and 7 V in open circuit conditions were typically measured under normalized solar spectrum (AM1.5 100 mW/cm ²), and around 6.3 mW/cm² and 8.5 V using a 150 W commercial lamp placed at 5 cm distance from the panel     

Steady-State and Transient Conductivity of Colloidal Solutions of Gold Nanobeads

Steady-state and transient conductance measurements of gold nanobeads solutions deposited on top of interdigitated electrodes have been performed. It is shown that the application of an electric field of moderate value between electrodes during the drying process of the droplet makes the resulting steady-state conductance value to increase significantly. The dynamics of the gold nanobeads in the solution has been studied by means of transient current measurements during the drying process and the effects correlated to the changes in the morphology of the association of the gold nanobeads when they reach the substrate. It is seen that the application of the electric field foster the formation of gold beads monolayers, chains, and dendritic associations which, in combination with the humidity conditions of the sample surface, are believed to be the reasons for the conductance increase.     

A fast low-cost solar cell spectral response measurement systemwith accuracy indicator

A novel automated spectral measurement system is presented. Special attention has been focused on the design in order to obtain rapid measurement facilities, minimize hardware and simplify serial communications between the different subsystems involved, resulting in a low-cost measurement system. It is controlled by an HP-9000 computer, through a fully menu-driven interface, and the primary measurement instrument is an HP-4142B modular source-monitor. A new indicator of measurement accuracy is defined, implemented and displayed in real time. This automated system has been employed intensively to study characteristics of different solar cell types in order to optimize their fabrication process. As such this automated measurement system is clearly useful for both research and fabrication     

Flow measurement hits home

The conception, design fabrication, and test of a demonstrator of a low-cost flowmeter for washing machines and other home appliances has been described in this article. Mechanical, thermal, and electric simulations were required to set the parameters of the system, and links between thermal and electrical domains were established through SPICE-equivalent circuits. Closed-loop measurements using a electro-thermal sigma-delta converter improve the linearity compared with open-loop differential voltage measurements. A novel design of the packaging may lead to an inexpensive unit price when commercially produced     

Voltage and pull-in time in current drive of electrostaticactuators

The absolute maximum value of the voltage developed across an electrostatic actuator when driven by a current source has been calculated as well as an absolute minimum for the pull-in time. These two results are calculated for a drive using a δ-pulse of current and numerical assessment is given to show that for a nonzero parasitic capacitance, a realistic shape of the current pulse, or a finite value of the damping coefficient do not increase the maximum value of the voltage developed beyond that limit and that the pull-in time is always larger than the analytical minimum. A scaled-up macromodel of an electrostatic actuator has been used to register voltage transients to validate the theoretical predictions