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Home Photovoltaics Basics

Introduction

Since sizing a renewable energy source like solar energy, you'll want to follow all the home efficiency steps suggested to make you home as efficient as possible before considering an installation of solar panels. That way, the amount of electricity needed will be minimized and your solar system will be much lower cost. The extreme case is an earthship home. They have been designed to be so efficient that they do not need air conditioning or heating. All the appliances and lamps are the most efficient available. So, the home can get all the electricity it needs from five small solar panels.

Solar Energy Components

The basic building block of a photovoltaic system is a solar cell. It is made of silicon semiconductor material and converts light into electricity. A matrix of solar cells are wired together to make a solar panel, which typically outputs 12, 24, or 48 volts direct current (Vdc). A single solar panel can be used individually for small charging chores such charging a 12 voltbatteryor charging electronic equipment such as cell phones. However, to supply electricity to a whole household, several or many solar panels must be wired together to form a solar array. This solar array is usually mounted on an equator facing roof top or a metal post. The electrical output of your solar array is totally dependent on the amount of direct sunlight that hits the panels. Any obstructions, such as trees or clouds, will severely reduce the amount of electricity produced.

Economics of Photovoltaics

Photovoltaic systems require a substantial economic investment, with the typical systems costing $15,000 to $30,000 before any incentives are applied. Over the life of the system, you'll pay about 25 cents per kilowatt-hour of electricity produced, compared to about 1- to 20 cents per kilowatt-hour for electricity currently purchased from the utility company. But as the cost of retail electricity increases, the financial return on photovoltaic systems will improve.

Solar Site Assessment

Some sites are better than others for producing photovoltaic power. The size and orientation of your home, the presence of shade, and possible zoning restrictions all effect the viability of PV systems for your site.

Cost and Benefits of Using Photovoltaics

The size of your investment in photovoltaic power will depend primarily upon the output of your system. This peak output is usually measured in watts. Residential systems can usually range from one to five thousand watts, will commercial systems range up to thirty kilowatts or more.

Grid-Tied Systems

Many utilities allow their customers to connect properly installed photovoltaic systems onto the existing electrical grid. These grid-tied systems can feed excess PV power back into the power grid any time the customer uses less power than the systems produces. This typically happens during the day when the sun is out and the occupants are not home or have minimal demands. These systems then draw power back from the utility grid when the customer consumes more than the PV system produces, such as during cloudy weather, at night, or when the system is out of operation.

Working With PV Installers

Almost all PV systems are installed by electrical contractors. Your understanding of PV basics will help you choose a competent contractor and effectively supervise their work. This is the best approach unless you have a lot of experience with complicated electrical installations.

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