Photovoltaic Systems: All About Grid-Connected PV Systems

Image Gallery Whether your goal is to lower your energy bill or to achieve total energy independence, “Solar Electricity Basics” is the introduction you need to generating energy from the sun. With this book as your guide, you can design, purchase and install the best photovoltaic system for your home or business. COVER: NEW SOCIETY PUBLISHERS

The following is an excerpt from Solar Electricity Basics by Dan Chiras (New Society Publishers, 2010). Richly illustrated and clearly written, Solar Electricity Basics is an indispensible primer for homeowners or small business owners looking to tap the power of the sun for electricity. Chiras, an expert in residential renewable energy and a MOTHER EARTH NEWS contributing editor, discusses the theoretical, practical and economic aspects of residential solar installations, including thorough yet easily understandable information about inverters, batteries and controllers, permits, system installation and maintenance, and much more. This excerpt is from Chapter 5, “Solar Electric Systems — What Are Your Options?” 

PV systems fall into three categories: (1) grid-connected, (2) grid-connected with battery backup and (3) off-grid. The information here will help you decide whether a grid-connected PV system suits your needs, lifestyle and pocketbook.

Grid-Connected PV Systems

Grid-connected PV systems are the most popular solar electric system on the market today. Grid-connected systems are so named because they are connected directly to the electrical grid — the vast network of electric wires that spans the nation and crisscrosses your neighborhood. These systems are sometimes referred to as “battery-less grid-connected” or “battery-less utility-tied” systems.

A grid-connected system consists of five main components: (1) a PV array, (2) an inverter, (3) the main service panel or breaker box, (4) safety disconnects and (5) meters.

To understand how a battery-less grid-connected system works, let’s begin with the PV array. The PV array produces DC electricity. It flows through wires to the inverter, which converts the DC electricity to AC electricity. (For more on AC and DC electricity, see “AC vs. DC Electricity” later in this article.)

The inverter doesn’t just convert the DC electricity to AC; it converts it to grid-compatible AC — that is, 60 cycles per second, 120-volt (or 240-volt) electricity. Because the inverter produces electricity in sync with the grid, inverters in these systems are often referred to as “synchronous” inverters.