Emergency Power Backup Systems Continued access to electrical service during power outages.  When bad weather or other conditions interrupt power service, homeowners can find themselves unable to heat or cool their homes or run necessary appliances and lights. While fireplaces can provide some heat and flashlights or lanterns can provide light, many appliances will remain unusable until power from the grid is restored. This situation can be serious if critical applications such as medical devices, telephone, home office computers, sump pumps, or refrigeration are threatened. Emergency backup systems currently available on the market make it possible for homeowners to have continued access to electrical service during power outages. These systems are typically based either on fossil-fuel-powered generators or on battery-based storage systems. While the goal of both approaches is the same - to produce backup power - they each have advantages and disadvantages. For emergency backup power during typical power outages, battery-based systems represent a fairly simple and silent alternative.
The two basic components of battery-based storage systems are an inverter/charger and a set of DC batteries. The inverter/charger converts AC power from the grid to DC to charge the batteries. When power from the grid is lost, the inverter converts the DC battery power to AC for use in the home. The length of time that a battery-based storage system can provide emergency power to the home depends on its overall capacity and the type and number of appliances connected to the backup system. Battery-based systems are not designed to provide power over an extended length of time. For example, product literature by Xantrex Technology, Inc., a producer of backup power systems, indicates that a typically configured 2000-4000 watt system can provide typical priority household appliance loads for 2 to 12 hours. However, power conservation can extend operating time considerably longer. Additionally, fossil fuel-fired generators or photovoltaic equipment can be integrated into some systems to replenish or supplement the batteries when power is not available from the grid, or to help the batteries support the home's load. These systems are well suited to maintaining service to furnaces, entertainment and home office electronics, lighting, microwave ovens, and refrigerators. Other appliances, such as electric heaters, electric water heaters, stoves, and air conditioners would place a large demand on the system, and quickly deplete the batteries. Therefore, they are not good candidates for battery-based backup power. Potential owners need to identify which appliances will be supported by backup power and determine the load needed to accommodate them. The capacity of the system can then be sized to fit the needs identified by the owner 
Backup systems are currently being marketed in the U.S. See manufacturers section for further details.
Depending upon the amount of power needed in the event of loss of power from the grid, whether cutover is manual or automatic, and many other factors, the cost of these systems will range from under $1000 to $5000 and more.
The units will typically require periodic maintenance to assure they are functional when needed. The cost benefits occur primarily when grid power is lost for extended periods of time, and the power backup unit prevents food spoiling in freezers or flooded basements.
While the pre-engineered systems are certified to comply with UL standards, a licensed electrician or technician will likely be required to install these systems. Consult local authorities for any code requirements.
Not Applicable
Some systems require a cool, dry, conditioned environment, and must be installed indoors in such locations as the basement or garage. Others are designed to be installed outdoors. A licensed electrician or technician will likely be required to install these systems.
Warranties run from 1 year to 3 years for the fossil-fueled generators depending upon the manufacturer and, in some cases, the specific type of generator. The Xantrex battery-based system carries a 2-1/2 year warranty.
Backup power systems can provide immediate electrical power to critical loads during natural or other disasters. For the battery backup system there is no noise, maintenance, or pollution normally associated with backup generators, although it is more costly per watt than many of the fossil fueled units. Costs of the systems vary, depending on size and options selected. | 
