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Harnessing a multitude of complementary green energy sources is the only plausible way to satisfy the energy demands of a greedy global economy. The potential of solar energy (being the most abundant) in fulfilling part of the energy requirements of mankind is immense and constitutes the focal point of this book. A self-powered solar tracker that points directly towards the sun by means of an integrated control mechanism with two degrees of rotational freedom was studied and developed. The electro-mechanical control system is based on a precisely-timed microcontroller circuit that first computes the altitude and azimuth of the sun in real-time and then drives a pair of stepper motors that steer the solar tracker towards it. A locally built fibre-glass parabolic dish, the surface of which is lined with a reflective vinyl mirror film, serves to concentrate solar rays on its surface.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
Harnessing a multitude of complementary green energy sources is the only plausible way to satisfy the energy demands of a greedy global economy. The potential of solar energy (being the most abundant) in fulfilling part of the energy requirements of mankind is immense and constitutes the focal point of this book. A self-powered solar tracker that points directly towards the sun thanks to an integrated control mechanism with two degrees of rotational freedom was studied and developed. The electro-mechanical control system is based on a precisely-timed microcontroller circuit that first computes the altitude and azimuth of the sun in real-time and then drives a pair of stepper motors that steers the solar tracker towards it. An indigenously built fibre-glass parabolic dish, whose surface was lined with a reflective vinyl mirror film served to concentrate sun rays incident on its surface.
Zafrullah Jagoo

Chapter 2. The Physics of the Sun

Abstract
The chapter starts by describing briefly the basic features of sun and then proceeds to deriving the relevant equations that allow the calculation of several parameters pertaining to the sun namely the eccentric anomaly, hour angle, and the position of the sun (azimuth and altitude) amongst others. The relevant formulae are valid at any spacial and temporal location on the earth. The rule which allows us to compute the sun’s position at any time is cross-checked with the US National Renewable Energy Laboratory’s Solar Position Algorithm and is shown to be in good agreement (\(<\)1 %) with the exact sun’s position at our present location (\(20^\circ 17^{\prime }\) S and \(57^\circ 33^{\prime }\) E).
Zafrullah Jagoo

Chapter 3. Solar Tracking

Abstract
The various types of solar trackers are reviewed in this chapter along with their merits and disadvantages. It has been shown that in terms of the relative power output, a dual-axes tracker is the most efficient system available. The step-by-step construction of a novel dual-axes solar tracker, that points directly towards the sun thanks to an integrated sun tracking mechanism with two degrees of rotational freedom, is presented in this chapter. Each stage of the design, with explicit explanation of all the components, and realisation of the solar tracker is detailed. The electro-mechanical control system is based on a precisely-timed microcontroller circuit that first computes the altitude and azimuth of the sun in real-time and then drives a pair of stepper motors that steers the system towards it. The system will track the sun throughout the day and return to its default position for night-time stowing. The whole set-up can be constructed in about 6 months at a record price of \({{\$}118.81}\) for the electronics circuitry that any generic solar tracker can utilize and \({{\$}159.78}\) for a tailor-made prototype frame.
Zafrullah Jagoo

Chapter 4. Solar Concentrators

Abstract
Concentrating solar technologies are in different stages of development; most of them have passed the testing and power production (on a small scale) phases and are being commercialised. Yielding the most power per area among all the solar concentrators is the parabolic dish and the latter was selected as our low-budget prototype of choice. The steps towards the final parabolic dish concentrator made with fibreglass have been enumerated in the pages of this chapter. To convert the parabolic dish to a solar parabolic concentrator, its surface has to be lined up with a reflective material so as to focus energy optimally. The different types of reflective materials have also been discussed with the pros and cons pointed out for each type. The choice of the solar concentrator along with the building materials, fibreglass and chrome vinyl reflector, were also fully justified in accordance with the ease of production and tight budget.
Zafrullah Jagoo

Chapter 5. Results and Discussion

Abstract
As a final test, the performance of the tracking solar concentrator in the open field was evaluated. Before jumping to the solar concentrator’s efficacy, the validity of the solar tracker’s motion was investigated and was in accordance with the actual sun position. Although the parabolic dish was constructed outside a laboratory, the high heat flux at the focussing aperture favoured the ignition/melting of several materials within a few seconds. In an effort to determine the power production of our solar concentrator, a water load, suspended at the focus, was allowed to be heated up rapidly and the power output was computed using various algorithms from the laws of thermodynamics. A constructed model based on the simplified Newton’s Law of Cooling could predict the rise in temperature whereby the kinetics of heat transfer are limited by convective cooling. The empirical power output of the 0.6 m\(^2\) tracking solar concentrator was found to be 176 W.
Zafrullah Jagoo

Chapter 6. Conclusion

Abstract
An overview of what has been achieved in this book is presented in this chapter. Starting from the position of the sun to the prototyping of the solar tracker and culminating at the construction of the solar concentrator is briefly explained. Future steps that can enhance the robustness of the solar tracker, the perfection of the solar paraboloid and the improvement of the reflective material are also exhibited. Ultimately, details about a braking mechanism as means to reduce the power consumption of the 30 W solar tracker is lucubrated.
Zafrullah Jagoo

Backmatter

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