THE BASICS OF BACKUP POWER:

REVIEWS AND COMPARISON OF DIFFERENT SYSTEMS FOR HOME AND COMMERCIAL USE

FIND ELECTRICAL POWER GENERATORS BY SPEC

A blackout can happen at any time. Often the grid may be down for days or even weeks. Backup power systems can supply electricity to critical loads or entire house when the grid is down. There are various kinds of emergency backup devices depending on the type of energy source they are using to produce electricity. When you are choosing the type of your system, the main things you get to decide are: the amount of backup electrical power you may need during a blackout and the length of time you want to produce it. To properly size your system see our sizing guide. You may want to add 10 to 20 percent safety margin for system derating and to prevent false tripping of your source's circuit breaker. Note, since many appliances have surge current exceeding their steady state current, you need to make sure your backup system has sufficient surge capacity to accommodate all the loads at start up. This is especially important for automatic systems. If you choose a manually activated system, you can turn off your loads before starting the backup source and then turn them back on sequentially. The table below provides basic features of the main types of power back up sources. Electric generators are generally the least expensive source of power. For a short-term blackouts an emergency portable generator is the most popular low-cost solution. For a long-term emergency a natural gas or propane-powered stationary genset with a transfer switch is probably the most cost effective solution. Such a system can provide electricity for as long as it has fuel. Home battery backup is not common because it is suitable only for a short term outages. And unlike portable generators that can be refueled, a battery recharge needs a source of electricity. Alternative energies, such as photovoltaic energy are becoming increasingly popular due to various incentives and rebates. However, they are still more expensive types of home backup (see cost comparison of energy sources).

BACKUP POWER SOURCE	MAIN FEATURES	PRO's	CON's	NOTES
PORTABLE GENERATOR	Runs on gasoline, diesel, propane, or natural gas (depending on the model) Power range: 500-17,500 W Gasoline models are good mainly for short-term outages Multi-fuel models running on LPG or NG may provide long-term power	Can be moved from place to place No professional installation is needed [unless you want to connect it to the house wiring via a transfer switch and/or to an external fuel source]	Limited run time (less than a day before refueling) unless hooked up to an external fuel source Very noisy No auto start Requires maintenance Burns fuel even when it idles	Must be run outdoor only Potential fire and carbon monoxide hazard if used improperly
STATIONARY STANDBY GENERATOR (WHOLE HOUSE GENERATOR)	Connects to the home wiring via a transfer switch Runs on diesel, propane or natural gas (depending on model) Highest power range (6kW -100's kW) The best type during long blackouts and as the whole house generator Typical transfer time with auto transfer switch: 10-30 seconds	Auto start option on many models Practically infinite run time when connected to natural gas line	Expensive Requires professionally installed transfer switch and fuel line Requires maintenance Noisy Burns fuel even when it idles	Installed outdoor on a cement pad and connected via a transfer switch
BATTERY BACKUP WITH DC-AC POWER INVERTER / CHARGER	Powers critical appliances via extension cords. May be permanently connected to the house wiring via a transfer switch Typical power for residential use: 5-10 kW Auto start systems have response time 16-36 ms	No maintenance required Quite May be installed indoor Low power consumption at no load (consumes power according to the actual load demand)	Limited run time (typically 2 to 12 hours) depending on the battery tank capacity	Look for a sealed deep cycle battery and a temperature compensated charger with a trickle mode to avoid battery overheating
BACKUP HOME GENERATOR VIA VEHICLE	Good for short outages and to power only essential loads Typical power 300 W- 5000W depending on the car (hybrid is the best) and inverter	Lowest cost No professional installation required	Engine must be ON all the time to avoid car battery discharge Power is limited by the rating of vehicle parts Limited run time	Exhaust fumes present potential hazard
SOLAR PANELS with a BATTERY SYSTEM and DC-AC INVERTER/ CHARGER	Photovoltaic (PV) panels charge battery bank Produces electricity only on bright days Can power stand alone AC loads or can be connected to the house wiring (in which case it requires a grid-interactive type of inverter with a transfer switch)	Utilizes renewable energy Quite No maintenance required Defrays energy cost or even let you sell electricity back to utility Federal and state incentives	The most expensive type Limited run time [depending on the battery tank's capacity] Requires professional installation	In off-grid installations it's worth to supplement the system by a diesel or a propane genset
WIND GENERATORS with BATTERY and DC-AC INVERTER	A wind turbine converts wind energy into electric energy. Includes a battery bank, charger and grid tie DC-AC inverter with auto transfer switch May be used primarily in rural areas	Uses renewable energy Federal and state incentives Defrays energy cost or even let you sell electricity back to utility	The second most expensive type after solar Limited run time [depending on the battery tank's capacity] Requires a tall tower	In off-grid installations it's worth to supplement the system by a diesel or propane genset

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