Double-Layer Orthogonal-Offset Platforms in fluid and insolation environments

Abstract

The DLOOP is a structure of non-overlapping tiles (typically corner connected) occupying two layers. Interest in the DLOOP arises from Photo-Voltaic (PV) tracking applications.

The tiles (PV modules) of contemporary tracking systems are within one contiguous layer, i.e. a side-by-side platform (SSP).

Trees collect solar energy using branching structures to support leaves which are, similar to PV modules, planar surfaces of solar energy transformation. The tree's form is naturally excellent for lowering structural stress in limbs and thermal stress in leaves. For analogous reasons, related to the creation of flow paths that would otherwise be blocked, this research hypothesised (and has subsequently shown) that: * the fluid (wind) dynamic force on tiles of high inclination SSP may be reduced (up to 30%) adopting DLOOP arrangements; and * the temperature of heated tiles in SSP may be reduced (up to 5K within nominal and hot terrestrial environments), by passive convective cooling, adopting DLOOP arrangements.

Fluid (wind) dynamic force is significant in PV applications because it typically exceeds the force of gravity on the tiles of SSP in 13m/s winds and increases with velocity squared. Hence reducing wind force by 30% should allow 40% more tiles to be fitted to contemporary tracking mechanisms.

Temperature is significant in PV applications because the performance of PV tiles typically falls 0.4%/K. Hence a 5K reduction in temperature should improve efficiency 2%.

A combination of wind-tunnel tests, Particle Image Velocimetry and Computational Fluid Dynamic (CFD) simulations using Reynolds Averaged Navier Stokes and Large Eddy Simulation turbulence models was used for the fluid dynamic research.

A combined Finite Element/CFD simulation of PV panels in platforms was developed to model temperature outcomes of thermal diffusion in solid materials and thermal diffusion, radiation and convection in the fluid (air).

If PV-tracking ranges are limited below those of the solar-vector, shading of the DLOOP lower by the upper layer occurs. This DLOOP self-shading raises unique cost-benefits associated with tracking ranges. Consequently, this research develops a means to quantify the insolation received by platforms accounting for technology and tracking range in diverse (Australian) climates.

Additionally, multiple tracking platforms may be placed in close proximity and suffer "Parasitic" energy losses when shaded by self-similar neighbours. Therefore, this research study introduces a natural no-shade scale to describe and optimise field layouts according to local insolation and economic conditions.