| Benefits:
Today's solar electric cells are a practical and environmentally friendly way of producing electricity for everyday use. By adding a solar electric system to your home or office, you will reduce the intake of electric power from your power company. This will reduce your monthly utility bill. Depending upon the local rate structure and the size of the system, the reduction will vary from 10% to 50% or more. More importantly, you will make an important contribution to the environment. Solar electricity is valuable to our future in many different ways.
- Free Energy From the Sun
- Reduce or Virtually Eliminate Utility Bill
- Environmentally Friendly
- Reduce dependence on Foreigh Oil
- Provide back up Power if Utility Power Fails
- Provide remote power where power is not available
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How It Works
The cells or thin film circuits of the solar modules are specially manufactured to respond to light by producing electric current. The scientific term for "solar electricity" is "photovoltaic" energy-which means electricity from light. The more light the cells get; the more electricity that can be produced. These cells when connected together, laminated and framed are called a 'solar module'. These modules are designed to produce electricity at convenient direct current (DC) voltages for storing in a battery or being directly converted into typical 120-230 volt alternating current (120 VAC).
Solar electricity can be used to run DC motors, or it may be stored in batteries for later use, or converted instantly into AC power and 'net metered' into the utility grid.
In a stand alone type solar electric system if household current is needed to run 120 volt AC powered appliances like found in most homes, the DC power stored in the battery bank must be changed from DC (direct current) to AC (alternating current) by an inverter.
An inverter is the device used to change solar electricity into regular household current.
In a utility intertied type solar electric system the DC power from the solar array is converted instantly into 120/240 volt AC power and fed directly into the utility power distribution system of the building. The power is 'net metered' and reduces power demand from the utility when the solar array is under sun. These systems can lower the power bill of a building.
Where to Install
In most instances the modules are installed on the roof of the building, but they can be mounted on a ground rack or on a pole mount. The major factor in deciding where to place the modules is to maximize exposure to the sun and avoid shading from 9am to 3pm.
Systems
The modularity and flexibility of solar electricity allows users to have system tailored to specific needs and preferences.
Aside from full or partial power, solar electricity may serve as a power source for a specific job. This could be electricity for a well pump, patio or street lighting or for a home security system or even a backyard waterfall. Typically, such systems consist of one of more modules and charge controller accompanied by a battery or batteries.
PV systems are composed of several individual components including arrays (multiple connected modules), inverters, controls, safety disconnects, and batteries. By assembling differing sizes of components together, systems can be built with varied power outputs to meet the demands of various loads.
Types of Systems
 Generally speaking, solar power systems may be categorized into three primary types, stand alone, battery back-up and utility (grid) connected. Any of these types systems may be designed to meet all or part of the user's electrical requirements.
Some applications need a system that includes a fuel power backup generator, wind turbine or water turbine. Typically, such "hybrid" systems share the load between the solar chargers and the back-up generator. Batteries are still required, plus the DC to AC inverter if regular AC loads will be powered.
The small stand alone DC system
Stand alone type systems are usually a utility power substitute. They generally include solar charging modules, storage batteries and controls/regulator.
Stand alone solar power systems use a charge controller to prevent over-charging the systems' battery. The small stand-alone system is in excellent replacement for kerosene lamps and noisy generators in a remote home, a recreational vehicle or a boat.. The actual sizing depends on the wattage of the loads and how often they are to be run.
The PV array charges the battery during daylight hours and the battery supplies power to the loads when needed. The charge regulator terminates the charging when the battery reaches full charge.
Stand alone AC-DC System
This system is the same as the previous system, except for the use of a DC to AC inverter. With the addition of an inverter, commonly available household appliances such as computers, power tools, vacuum cleaners, washing machines and kitchen appliances can used.
High quality DC to AC inverters are available with power outputs ranging from one hundred watts to ten kilowatts and more, and conversion efficiencies greater than 90 percent. Most larger inverters also have the ability to serve as battery chargers from a backup generator when more power is needed than can be supplied by the solar modules.
Back-up AC System
A back-up or stand-alone AC solar electric system will usually have a PV array of ten or more modules, battery bank and one or more inverters. The utility will back-up the solar and run the loads when available and needed. If utility power fails the power from the solar can run the backed up loads.
Utility Inter-Connected System (Grid-tied)
These are the simplest systems and require no batteries. Designed not for back-up power but instead these systems are designed to contribute power back into the existing power supply.
By lowering a buildings power bills these systems will pay for themselves over a number of years and reduce the air pollution produced by utility companies that burn coal. Contributing clean, green power from your own roof helps create jobs and is the alternative to buying fossil fuel derived electricity.
Utility intertied systems are generally designed to reduce power demands from the utility by 'net metering' power or in some cases to sell power back to the utility. A typical system might include solar modules, a mounting structure, and AC inverter/control for the power to be fed back through the building's 120/208/240 volt AC power distribution system.
All electrical system wiring should be performed by competent electricians and should be in compliance with the National Electrical Code (NEC) and inspected by your local county/city electrical inspector.
Warranty
Warranties vary by manufacturer. The majority of Solar modules are warranted for at least 20 years and inverter warranties average 10 years.
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