Proposed photovoltaic module form factor to reduce levelized cost of energy
This paper discusses a proposed photovoltaic (PV) module form factor designed for utility-scale, one-axis tracking projects. The purpose of the form factor is to: 1) reduce total installed costs for utility-scale projects; 2) improve module reliability; 3) reduce operating and maintenance (O&M) costs, and 4) improve the project return on investment. The proposed module uses a double-glass construction to improve reliability and service lifetime in a form factor that is longer and narrower than existing 60-cell modules. This form factor places more module area per linear meter of torque tube when used with single-axis trackers. These changes are expected to lower the levelized cost of energy.
The effect of cell thickness on module reliability
This paper addresses the issue of the reliability of modules using ultra-thin crystalline silicon cells. Do thin cells have a greater likelihood of cracking during production, transport, installation or use and if so does this result in long term degradation of the power? The present qualification test sequence, IEC 61215 does not adequately address this issue, The only mechanical test in IEC 61215 is a static mechanical load test consisting of three load cycles that are performed after the accelerated stress tests. So even if this mechanical load test does break cells, it is unlikely to result in significant power loss. BP Solar has developed a test sequence for evaluation of cracked cells in PV modules. The test sequence incorporates a dynamic mechanical load test performed before the 50 thermal cycles/10 humidity freeze cycles of IEC 61215. Usually there is no significant power loss after the dynamic load testing. However, the subsequent thermal cycling opens up the cracks that propagated during the dynamic load test resulting in significant power loss. Having a test sequence that identifies damaged cells allows us to develop processes and handling procedures to minimize or eliminate damage to the ultra-thin cells, resulting in reliable modules.
An improved nonintrusive global–local approach for sharp thermal gradients in a standard FEA platform
Several classes of important engineering problems—in this case, problems exhibiting sharp thermal gradients—have solution features spanning multiple spatial scales and, therefore, necessitate advanced hp finite element discretizations. Although hp‐FEM is unavailable off‐the‐shelf in many predominant commercial analysis software packages, the authors herein propose a novel method to introduce these capabilities via a generalized FEM nonintrusively in a standard finite element analysis (FEA) platform. The methodology is demonstrated on two verification problems as well as a representative, industrial‐scale problem. Numerical results show that the techniques utilized allow for accurate resolution of localized thermal features on structural‐scale meshes without hp‐adaptivity or the ability to account for complex and very localized loads in the FEA code itself. This methodology enables the user to take advantage of all the benefits of both hp‐FEM discretizations and the appealing features of many available computer‐aided engineering /FEA software packages to obtain optimal convergence for challenging multiscale problems. Copyright © 2012 John Wiley & Sons, Ltd.