Viscous rotary vane actuator/damper

A compact viscous rotary actuator/damper for use on the Mariner '71 and Viking Programs was developed. Several functions were combined into this single mechanism to control the deployment, latching, and damping of the solar panel arrays used on these space vehicles. The design, development, and testing of the actuator/damper are described, and major problems encountered are discussed

Global security

The presentation explores the NATO Space Surveillance Network and the recent developments in updating it with state of the art infrared sensors and high bandwidth communication satellites using triple junction solar panel arrays

Experimental assessment of RANS models for wind load estimation over solar-panel arrays

This article belongs to the Special Issue Application of Computational Fluid Dynamics in Mechanical EngineeringThis paper reports a comparison between wind-tunnel measurements and numerical simulations to assess the capabilities of Reynolds-Averaged Navier-Stokes models to estimate the wind load over solar-panel arrays. The free airstream impinging on solar-panel arrays creates a complex separated flow at large Reynolds number, which is severely challenging for the current Reynolds-Averaged Navier-Stokes models. The Reynolds-Averaged Navier-Stokes models compared in this article are k-ϵ, Shear-Stress Transport k-ω, transition and Reynolds Shear Model. Particle Image Velocimetry measurements are performed to investigate the mean flow-velocity and turbulent-kinetic-energy fields. Pressure taps are located in the surface of the solar panel model in order to obtain static pressure measurements. All the Reynolds-Averaged Navier-Stokes models predict accurate average velocity fields when compared with the experimental ones. One of the challenging factor is to predict correctly the thickness of the turbulent wake. In this aspect, Reynolds Shear provides the best results, reproducing the wake shrink observed on the 3rd panel in the experiment. On the other hand, some other features, most notably the blockage encountered by the flow below the panels, are not correctly reproduced by any of the models. The pressure distributions over the 1st panel obtained from the different Reynolds-Averaged Navier-Stokes models show good agreement with the pressure measurements. However, for the rest of the panels Reynolds-Averaged Navier-Stokes fidelity is severely challenged. Overall, the Reynolds Shear model provides the best pressure estimation in terms of pressure difference between the front and back sides of the panels.The authors wish to thanks Carlos Cobos for contributing the realisation of the experimental setup and J. Rodríguez for providing the PIV system. The authors acknowledge S. Discetti and A. Ianiro for insightful comments and discussions

Project SPACE: Solar Panel Automated Cleaning Environment

The goal of Project SPACE is to create an automated solar panel cleaner that will address the adverse impact of soiling on commercial photovoltaic cells. Specifically, we hoped to create a device that increases the maximum power output of a soiled panel by 10% (recovering the amount of power lost) while still costing under $500 and operating for up to 7.0 years. A successful design should operate without the use of water. This will help solar panel arrays achieve a production output closer to their maximum potential and save companies on costs associated energy generation. The current apparatus utilizes a brush cleaning system that cleans on set cleaning cycles. The device uses the combination of a gear train (with 48 pitch Delrin gears) and a 12V DC motor to spin both a 5.00 foot long, 0.25 inch diameter vacuum brush shaft and drive two sets of two wheels. The power source for the drive train is a 12V deep cycle lead-acid battery. Our light weight design eliminates water usage during cleaning and reduces the potential dangers stemming from manual labor. Our design’s retail price was estimated to be around$700 with a payback period of less than 3.5 years. To date, we have created a device that improves the efficiency of soiled solar panels by 3.5% after two runs over the solar panel. We hope that our final design will continue to expand the growth of solar energy globally

Use of Glass Reinforced Concrete (GRC) as a substrate for photovoltaic modules

A substrate for flat plate photovoltaic solar panel arrays using a glass fiber reinforced concrete (GRC) material was developed. The installed cost of this GRC panel is 30% less than the cost goal of the Near Term Low-Cost Flat Plate Photovoltaic Solar Array Program. The 4 ft by 8 ft panel is fabricated from readily available inexpensive materials, weighs a nominal 190 lbs., has exceptionally good strength and durability properties (rigid and resists weathering), is amenable to mass production and is easily installed on simple mountings. Solar cells are encapsulated in ethylene/vinyl acetate with Tedlar backing and Korad cover film. The laminates are attached to the GRC substrate with acrylic transfer tape and edge sealed with silicone RTV adhesive

Estimation of cavity pressures in air-permeable, multi-layer systems using a lumped-leakage approach

For conventional buildings, the proper estimation of wind-induced pressures on the external façade, the roof surface, or the net pressures across elements like a canopy or parapet, which are exposed to wind on both sides, can be easily done using conventional wind tunnel tests. But in the case of air-permeable multi-layer systems, which have gaps or porosity in the external layer along with a cavity between the external and inner layers, the estimation of wind loading across the external layer or in the inner cavity by wind tunnel tests can be quite difficult due to practical difficulties in exactly simulating the dimensions of the gaps in the physical model with small model scales or other practical issues related to the tubing of the pressure sensors. Pressure equalization plays a major role on the wind loading on individual members of multi-layer systems and in this study, an analytical model to estimate the time- varying cavity pressure distributions in a double-layer system with an air-permeable outer layer was developed, given the external pressure on the outer surface. The pressure drop associated with the flow through the gaps in the external layer was modeled using orifice flow equation and mass conservation equation (Oh. J.H. & Kopp, G.A., 2014). The model accounts the geometric parameters like the cavity depth (H) which is the distance between the outer layer and the inner non-porous layer along with loss coefficient for the orifice flow through the gaps in the external layer. Moreover, the pressure drop due to flow through the gaps (G) in the external layer are accounted based on a lumped-leakage approach. The results from the analytical model are compared with wind-induced loads obtained from the wind tunnel test of roof-mounted photovoltaic solar array system with high G/H ratio obtained from Stenabaugh (2015)

The Economics of Residential Solar and Battery Storage: Analyzing the Impact of the Joint IOU Proposal for Net Metering 3.0 in California

The California Public Utilities Commission (CPUC) is currently deciding on the structure of the next net metering program, which will determine how customers who install solar panels (and battery storage) under this new program will be compensated for excess energy that they export to the grid, and the additional fees that these solar customers will have to pay. The major investor-owned utility (IOU) companies in the state and some legislators have argued that the current net metering programs are far too generous to the customers and that they create an inequity by favoring the wealthy and causing a cost shift to the poorer non-solar customers. The IOUs have jointly proposed a set of regulations to the CPUC. In this paper, we examine the financial implications to residential customers who go solar under the new net metering program if the joint IOU proposal were to be adopted. We examine the case of a hypothetical southern California home that consumes the average amount of electricity (for that region) and estimate its electricity bills for various load profiles, assuming no solar or battery storage, with solar alone, and with solar and battery storage. For the two latter scenarios, we determine the ideal system configuration that will maximize the customer’s financial returns. In all cases, we determine that the joint IOU proposal for net metering will make residential solar panel and battery storage installations financially unattractive even in the best-case scenarios. In short, if the CPUC adopts the joint IOU proposal then residential solar installations in the state would likely come to an abrupt stop. We also analyze the economics of going off-grid (where a customer completely cuts himself off from the electrical grid) and find that it does not make sense for customers to go off-grid without being willing to cut consumption or make other compromises

Tilt Angle Optimization for Bifacial Solar in an Array for Every County of the United States

In the 21st century, governments worldwide are striving to become more reliant on renewable energy technologies to reduce greenhouse gas emissions, address climate change, and decrease their carbon footprint. Photovoltaic (PV) technology is gaining more attention, despite PV panels consuming significant land resources, while expanding populations require more land for agriculture. In this research, we focus on bifacial solar panels, as they generate relatively high power per square area, reducing the payback period. Bifacial panels can convert the irradiances falling on both the front and back surfaces into electricity. Although there are many studies in the field of tilt optimization and types of PV panels used, there is a lack of research focusing on a bifacial panel array. Our primary objective is to develop a model of bifacial panels to predict the power generated, and our secondary objective is to use that model to find the optimum tilt for every county in the United States and explore the effects of climate, temperature, and latitude. To calculate the ideal tilt angle for various locations across the country, we used a combination of modeling and simulation techniques in Python, including a Python optimization tool. Our findings indicate that the ideal tilt angle for bifacial solar panels in an array varies considerably depending on the location. Our data can be used to optimize the setup and operation of bifacial solar panels in the US, resulting in more cost-effective and efficient energy production.https://ecommons.udayton.edu/stander_posters/4028/thumbnail.jp