Page 31 - Solar Power in Building Design The Engineer's Complete Design Resource

1

SOLAR POWER SYSTEM PHYSICS

Introduction

Solar, or photovoltaic (PV), cells are electronic devices that essentially convert the
solar energy of sunlight into electric energy or electricity. The physics of solar cells is
based on the same semiconductor principles as diodes and transistors, which form the
building blocks of the entire world of electronics.
Solar cells convert energy as long as there is sunlight. In the evenings and during cloudy
conditions, the conversion process diminishes. It stops completely at dusk and resumes at
dawn. Solar cells do not store electricity, but batteries can be used to store the energy.
One of the most fascinating aspects of solar cells is their ability to convert the most
abundant and free form of energy into electricity, without moving parts or components
and without producing any adverse forms of pollution that affect the ecology, as is
associated with most known forms of nonrenewable energy production methods, such
as fossil fuel, hydroelectric, or nuclear energy plants.
In this chapter we will review the overall solar energy conversion process, system
configurations, and the economics associated with the technology. We will also briefly
look into the mechanism of hydrogen fuel cells.
In Chapter 2 of this book we will review the fundamentals of solar power cogen-
eration design and explore a number of applications including an actual design of a
500-kilowatt (kW) solar power installation project, which also includes a detailed
analysis of all system design parameters.

A Brief History of the Photoelectric

Phenomenon

In the later part of the century, physicists discovered a phenomenon: when light is
incident on liquids or metal cell surfaces, electrons are released. However, no one had
an explanation for this bizarre occurrence. At the turn of the century, Albert Einstein

1
Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.