Today's Solar Electric Cells Are A Practical & Environmentally Friendly Way Of Producing Electricity For Everyday Use!
For more than 50 years, solar electric technology has been developed and refined, and is now powering countless installations worldwide. For a brief introduction to the history of solar electricity click here.
Big Frog Mountain Corporation's power systems are being used for utility companies, businesses, remote cabins, homes, RV's, boats, water pumps, telecommunications stations, outdoor lighting, and many more uses all over the world.
Other applications for our products are continuing to arise with new systems being installed every day. Whether the job is to lower utility bills, fully replace fossil fuel-generated power for lights and appliances, or to simply trickle charge a spare battery, solar electricity has been proven to be clean, safe and reliable.
The modular nature of solar electric systems, permits incremental power system purchases, ease of expansion, simple maintenance, and easy repair or replacement of system components.
How It Works
PV modules are usually installed on special ground or pole mounting structures. Modules may be mounted on rooftops provided that proper building and safety precautions are observed. For more output, modules are sometimes installed on a tracker - a mounting structure that moves to continually face the sun throughout the day.
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.
Most American household appliances are designed to run on standard one hundred twenty volt AC power rather than on 12 or 24 volts DC. Those living outside the USA are typically using 230 volt 50Hz AC electricity. Combining batteries with an efficient AC inverter allows you to use your standard appliances with solar electricity.
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
At the site, the best place for solar electric module installation is away from the main path of activity. Mounting modules on a roof is one way to keep them protected and out of the way.
Get the most out of the sun.
The more light solar modules receive, the more power they will produce. It's critically important to keep your solar modules away from shade. Here are a few sure ways to get the most out of a solar electric system.
Direct sunlight for the longest possible time is most important in order to get the most power per day from a photovoltaic system.
When choosing the installation site, be sure there is nothing to shade the modules, especially during the prime sunlight hours of 9 a.m. to 3 p.m.
Even the shadow from a telephone line can greatly reduce the module's power output.
If the roof of a building gets lots of shade install the modules on a separate mount.
Tilt for maximum exposure. In the Northern Hemisphere the panels will generally receive the most solar radiation when mounted at an angle (latitude plus 15 degrees) facing towards the south and facing Northward for those living down under. The pitch or angle for a stationary module will generally be the degree of latitude of the site plus 10 to 15 degrees.
Mounting the modules at the best angle means that they'll get more direct sun. The best possible tilt for a module is one that puts it at right angles to the noontime sun.
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.
Types of Systems
Generally speaking, solar electric systems may be categorized into three primary types, stand alone, back-up and utility connected. Any of these types systems may be designed to meet all or part of the user's electrical requirements.
Stand alone type systems are usually a utility power substitute. They generally include solar charging modules, storage batteries and controls/regulator. Ground or roof mounted systems will require a mounting structure, and if 120/240 volt AC power (typical household current) is desired, a DC (direct current) to AC (alternating current) inverter will also be required.
The batteries used for most stand alone type solar electric systems are different than the ones used in an automobile. Storage batteries for solar electricity are called deep cycle batteries. These batteries are designed to be recharged many times and be able to provide a steady amount of power over a long period of time. There are many other ways that the power can be stored as well.
Stand alone solar power systems use a charge controller to prevent over-charging the systems' battery.
A charge controller is wired between the solar modules and the battery to monitor and control the current from the modules and shut the current off when the battery is fully charged. This prevents over-charging and damage to the batteries.
Efficient DC appliances help make solar electricity even more economical in many cases and you may be surprised by the variety of DC appliances available. There are TV's, stereos and fluorescent lights, to name a few. Folks that travel in an RV (recreational vehicle) are usually very familiar with the abundant supply of DC powered appliances.
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.
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 size of the PV array and battery bank will depend upon individual requirements. 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. The load center may contain meters to monitor system operation and necessary fuses to protect wiring in the event of a malfunction or short circuit in the building.
Stand alone AC-DC System
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. To ensure reliable system operation, the inverter should be carefully matched to the loads that will be run. 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. Often the generator will be wired to an automatic cranking device. This redundancy is important for continuously operating critical loads, such as information systems, refrigerators and other critical equipment.
As the loads (power requirements) on the system are increased, a larger solar array and more battery storage will be required. The more efficient the appliances - the lower the cost for a system will be.
Back-up AC System
In most businesses and homes, an AC only system simplifies wiring by allowing the use of low cost, readily available switches, outlets, and fixtures. Savings on wire cost are significant, because the large gauge wire required for efficient transmission of low voltage DC power over long runs is avoided.
Utility Intertied System
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. Safety issues have now all been satisfied as far as islanding potential (sending power down the line when the utility power is off -is not possible) and reliability. These systems automatically 'shut off' if utility power goes off line. This protects line workers from power being back fed into the grid during an outage. Once utility power returns the utility intertied inverter resumes normal operation.
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. These systems also help the utility company reduce 'peak load' during the day. 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. These utility connected renewable energy systems can certainly help offset a building's utility bills while helping the utility reduce 'peak hour demands'. 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.
Big Frog Mountain brings you ENERGY
ENERGY STAR qualified products use less energy than conventional products. And money isn't all you're saving by purchasing products that use less energy, you're also helping to save the environment. As an ENERGY STAR partner, Big Frog Mountain is proud to offer you products with the ENERGY STAR label. For more information, visit www.energystar.gov
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