Backyard Solar: Off-Grid Electrical Applications

INTRODUCTION

What You Can Power Off-Grid

Solar Panels

The Problem with Connecting Directly to a Load

The LM2596 Buck Converter Solution

FREE ELECTRICITY! Our sun impacts everything here on earth. The earth acts like a huge sponge and a virtual expressway for incoming solar radiation. Most of this sun-generated solar radiation bounces off earth’s ionosphere and travels on into deep space. However, some of this radiation washes over our earth and electrically affects certain solid materials (such as silicon). We can use the electricity produced in the silicon to get DC to energize devices we use.

Silicon is a good conductor of electricity and is affected by the presence of photons—discrete units of light energy radiated out from the sun. The frequency spectrum of solar energy ranges from ultra violet (UV) to infrared. Around 30% of light is visible. Yet over 50% is within the infrared frequency range. You can’t see it, but combined, the photons in UV and the visible range contain enough energy to affect electrons in certain materials such as silicon. It can also affect your body if you’re out in the sun too long.

This is a fun book about using this solar energy to do things—light, heat, cool, vibrate, or rotate. This book is about building circuits and connecting devices to demonstrate the value of solar power in our world.

To build these applications, you’ll need, as a minimum, a solar panel, a way to stabilize the varying photon waves washing over the panel, and a load that reacts to the incoming electrical energy.

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What You Can Power Off-Grid

Here are typical applications that can be powered by solar. Those covered in this book are marked with the Application Number (APP__):

TABLE 1

Uses for Solar Power

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Solar Panels

Solar panels are used to convert sunlight into electrical power. They’re identified by the watts of power they generate. Watts equal voltage times current (W=E.I). Connect panels together and you can produce kilowatts (thousands of watts) of DC power. And it all starts with photons making contact with a solar cell containing silicon.

Here are three types of solar devices you’ll encounter in your adventure exploring solar-based electricity.

Monocrystalline  Polycrystalline  Amorphous

Figure 1 – Three types of solar cells.

Monocrystaline  Polycrystalline  Amorphous

a  b  c

Figure 2a,b,c – Common types of solar panels.

The Problem with Connecting Directly to a Load

The output of a solar panel is not static. Its voltage is constantly changing depending on when the waves of photon particles (solar radiation from eruptions on the surface of the sun) arrive and wash over the earth. This can be seen in the inverter displays of the voltage being produced by a rooftop solar array.

Figure 3 – Photon