The following design methodology was created, employed and demonstrated in an example system. The system includes three units to demonstrate the mesh network and its functionality with one unit connected directly to a broadband source and the other two functioning as relays. It was decided that the system use ultracapacitors where possible to demonstrate their potential in such an application and the feasibility of implementing such a system. The sizing of the electronic components was determined using PVSyst. The associated converters and controllers were selected to optimize efficiency while minimizing cost and necessary components.
Mechanical components including the structural elements, mounting hardware, and fasteners were selected based upon the following criteria: cost, weight, strength, component life, transportability, ease of use, and maintenance. The structural support system was designed to hold the solar array at the optimum angle for the latitude at which the system will be utilized. Using the design methodology, several example systems were built for testing.
Include here exactly how this was done - e. g. screen shots explanations. For the mechanical design show how this was done. For the components - give a list and a weblinks to all parts.
===Sizing of system parts===
The frame is constructed of 2x4s for the initial prototype with a field quality prototype being constructed from 1in (1/16th in) aluminum angles. A simple plastic storage container functioned as a waterproof housing to protect all necessary electronic components. This was done using a simple container and waterproofing it with silicone glue on the seams. The chosen container is a Sterilite 25-quart modular latch box. A rack to hold the ultracapcitors in the waterproof housing was designed using UniGraphics NX 7.5 and printed using a reprap machine. The profile for the part can be seen below. The final product was printed to a thickness of 1/2in.
The .stl file can be found here – Maxwell 3,000 Farad ultracapcitor holder.
Each mechanical component was modeled using UniGraphics NX 7.5 and is shown in the image below.
Material properties for each mechanical component were assessed to ensure all components could withstand the loading conditions including wind loads and snow loads (PV Systems Engineering 2006). The wind load was calculated to be
46psf using the following equations.
Velocity pressure (q) = 0.00256*Kz*Kzt*Kd*V2*I
Where Kz = celocity pressure exposure coefficient at height z
I = importance factor
Design Wind Pressure (p) = q *G*Cf
Where G = gust effect factor = 0.85
The snow load was assumed to be less than 8 psf as is recommended in Photovoltaic Systems Engineering by Roger Messenger and Jerry Ventre. This yields a combined load force of
56 psf. Each mechanical component was then sized using a factor of safety of 2 as is recommended by the American Society of Civil Engineers. The factor of safety was determined using the following equation. Factor of Safety = Factor of Safety = Material Strength / Design Load
Using 6061 aluminum angles with a yield strength of 34,000 and a max stress of 16,600 psi under the design loading conditions results in a factor of safety of 2.
A finite element analysis was also performed on the frame members using Abaqus 6.11. The analysis confirmed that 1in aluminum angles to be used on the field testing prototype will withstand the loading conditions while accounting for the safety factor of 2. A tetrahedral mesh was used and seeded every 20 mm along the edges as can be seen in the picture below.
The boundary conditions set secured the bottom of the frame to the roof preventing and displacement or rotation. The applied load was placed on the frame of the module which is directly attached to the support structure itself. The applied load of
56 psf was distributed around the module frame. The boundary and loading conditions for each position can be seen below.
Boundary and loading conditions at the 60ͦ tilt angle.
The stress distribution can be seen in the
picture below . The greatest amount of stress equated to 18,600 psi.
The implementation of the hardware is going to be made using DC/DC converters as shown in the schematic shown below
Describe what is going on below <center>[[Image: solarinternet. png| 600px]]</center>
The firing of the MOSFET’s is done using a Micro controller based circuit, it has been proposed to use the Arduino Uno to implement this circuit. The Perturb and Observe algorithm being considered to be used to implement the MPPT control [http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=1461481&openedRefinements%3D*%26filter%3DAND%28NOT%284283010803%29%29%26searchField%3DSearch+All%26queryText%3DPerturb+And+Observe+.LB.P.AND.O.RB.].The advantage of this method is , it is easy to implement and robust in structure which increases the efficiency of the system.