 SOLAR MODULES are installed in groups of 1 to 12 modules on a solar mount, which in turn attaches to a building (roof), or atop a metal post in the yard. Together this is called a solar array. Each solar module is wired to the other modules in that array by sunlight tolerant solar interconnect wiring. Several arrays may be wired to a solar combiner box where they are all connected to heavier underground wires taking the power to the battery and equipment room.
 A MICRO-HYDRO ELECTRIC GENERATOR can be installed on the lowest part of a stream with the proper qualifications (such as the stream having enough fall or "head" from the time it enters your property to the time it leaves). A small dam of sorts is built to divert water into a pipe (or two) which carries the water down to the hydro unit where a set of nozzles spray water with pressure onto a wheel with spoon-like cups, thus turning it very quickly. This wheel is connected to an alternator which produces DC electricity. The electricity is sent through a charge controller to the battery bank where it is used to charge the batteries.
A CHARGE CONTROLLER is a small wall-mounted component receiving the power from solar, wind, or micro-hydro generators, and controlling the flow of power to the battery. To prevent battery damage from overcharging, the charge control automatically cuts back, stops, or diverts the charge when batteries become full. A charge control may have manual control switches and may have meters or lights to show the status of the charging process.
The BATTERY BANK is the heart (some people say the weak link) of any A-E system. Batteries receive and store DC electrical energy, and can instantly supply large surges of stored electricity as needed to start or run heavy power appliances that the solar panels or hydro electric generator alone could not power. This large power capability can be a fire hazard just like utility company power so fuses and circuit breakers on every circuit connected to a battery are essential. Battery size is chosen for both surge power requirements and for the amount of reserve power needed. Typically, 2 to 12 square feet of batteries weighing 200 to 1000 pounds are enclosed in a battery box with a vent pipe to the outside.
Deciding on just the right battery is a critical decision because batteries, unlike other A-E system components, require monitoring and maintenance to ensure the longest life span. Since the battery is the only component that needs consistent monitoring and maintenance, you need to balance the variables of the investment cost, the battery warranty, and your time available for routine task
The INVERTER is the brain or major electronic component of a power system. It converts DC power stored in batteries to 120 volt AC, standard household power. Short, heavy cables with a large fuse or circuit breaker carry battery power to the inverter. After conversion to AC, power from the inverter connects into the circuit breaker box of the house in place of utility lines. The house breaker box routes power to lights, appliances, and outlets of the house. Inverters for home power come in ratings from 50 to 5500 watts.
Two choices of inverters in types of power are available: sine-wave or modified sine-wave. The sine-wave inverters will provide exceptionally "clean" power for sensitive equipment, such as computer systems, copy equipment, microwaves, audio equipment, bread makers and some motors. For instance, microwaves can take 30% longer to cook, fan motors may hum, stereos may have static, and copiers fail to operate in a system using a modified sine-wave inverter. As with other components, weigh these considerations against the cost differences for the best choice in your system.
 A STANDBY INVERTER/CHARGER is an inverter that also has a battery charger and transfer relay built in. When the input terminals of a standby inverter/charger receive power from an outside source of AC (a generator or utility power) the inverter stops producing AC power from the batteries, and instead passes generator or utility AC power straight through to the house. At the same time it uses the generator or utility power to recharge the batteries. Some standby inverters even auto-start the generator when batteries need charging. A separate battery charger can be used instead of (or in addition to) a standby inverter/charger.
 An ENGINE GENERATOR producing 120 volt AC power is usually part of the system. This is a second source of AC power and a backup for charging the battery (when there is a shortfall in solar, hydro or wind power); a temporary need for additional power for construction or visitors; or in case of a breakdown of other equipment. Just starting the generator begins the standby inverter charging process. The best generators start by a switch in the house.
A generator is located outside, usually in its own shed at least 30 feet away to avoid noise. For reasons of health and safety, it cannot go in a basement. 120 volts AC power from the generator goes through a circuit breaker, then is wired into the power room to run battery charger(s) as well as supply the AC power to the house whenever the generator runs. Since both battery charger and AC transfer relay are usually part of a standby inverter, the generator power usually connects only to the AC INPUT terminals of the inverter, not to the house breaker box.
Generators that run at 1800 RPM will greatly outlast generators that run at 3600 RPM. Diesel generators have greater endurance than gasoline, natural gas/LP generators and require less maintenance. For more information about generators check out www.bowerspower.com.
A few special lower cost generators are made to produce only battery charging DC voltage instead of AC. These send DC power directly to the battery. For information about storing fuel go to www.PRIProducts.com .
FUSES or CIRCUIT BREAKERS are necessary in all DC wiring between the batteries and other power system components described, but are not shown in the drawing(s). This prevents fires and equipment damage in the event of a malfunction. Breakers might each be a separate component, or might be built into a power center. In contrast, the AC breaker box for household wiring is part of the house wiring, not usually included with power generating equipment.
 METERS, like the gas and temperature gauges in a car, are necessary to show that everything is working. Solar charge indicating meters are often built into the charge controller to confirm the charging process instantly. Other meters show how much power is being consumed, and confirm how much power is available. These battery system monitors can be located in the power room, or at a convenient spot in the home for easier checking.
A POWER CENTER is a product including system meters, DC circuit breakers, and wiring connections for batteries, inverter, solar and other charging sources. Power centers are easier to install and to pass building code than would be selecting, buying, and installing all those parts separately. The power room is simplified, with just a few main components: power center with charge controller attached, a standby inverter-charger, and a battery box on the floor. Some power centers are shipped as a completely assembled power system.
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