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Installing Solar Energy

Installing Solar Panels

Since sizing a renewable energy source like solar energy, you'll want to follow all the home efficiency steps suggested on our Home Efficiency, Heating Cooling, and Home Insulation pages to make sure you home is as efficient as possible before considering an installation of solar panels. That way, the amount of electricity needed by you solar PV system 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 volt battery or charging electronic equipment such as cell phones.

Solar cell
The Solar Cell is the Basic Building Block of a PV System

However, to supply electricity to a whole household, several or many solar cells must be wired together to form a solar panel and then a solar array. This solar array is usually mounted on an equator facing roof top, platform, 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.

Solar array
Solar PV Array

Depending on your needs the PV system can be designed to output different DC voltages. By wiring Solar panels in series, parallel, or both you can increase the output voltage to the desired level. Typically, if your panels are physically located far away (says more than 50 feet) from your loads, a higher voltage, such as a 48 volt output works better. As a general rule of thumb, panels of the same type and voltage production should be used together.

Economics of Photovoltaics

Photovoltaic systems used to require a substantial economic investment, with the typical systems costing $15,000 to $30,000 before any incentives are applied. However, within the past year solar PV has really come down in price. A 1 kilowatt system that could supply the average family of three used to cost $17,000 to $25,000. Now it can be had for less than $5,000. Prices for PV has come down so much that Google has abandoned many of the alternative Solar Concentrating investments because they can no longer compete watt for watt with PV. Why? Two reasons. The Great Recession of 2008 to 2011 bankrupted many Solar PV manufacturers. Their inventories of solar panels have flooded the markets and are sinking prices. The other reason is, you guessed it, China's high production of solar panels is also driving prices down. Especially solar panels from ZheJiang province, near Shanghai, China is becoming the world capital for Solar panels and water heaters.

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.

Also, the further away from the equator your home is, the more tilted your solar panels must be. This is called insolation. It is a measure of the amount of sun light that hits your property during the winter solstice, December 21. In some northern states the PV panels must mounted almost vertically.

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, while commercial systems can exceed thirty kilowatts. The decision to investment in solar electric is usually measured in number of years of payback. In other words, the reduced electric bills from installing a Solar PV system will eventually pay off the system. This is based on kilowatt hour charges by the utility at today's rates. As rate go up, the payback period decreases. You also have other incentives to install now: goverment tax credits, utility and installer rebates, as well as falling PV prices.

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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