In many areas, beset by frequent electrical outages, or destructive power surges, backup generators are an essential purchase. Lightning strikes often trip the circuit breakers in substations, and high winds can bring cables crashing down, disrupting electricity supplies for hours or even days. During long and hot summers, many homes and businesses rely upon air conditioning to make life bearable, often overloading the capacity of the grid and causing brownouts.

Losing power, at best, is an inconvenience. At worst, it can cost a great deal of money and even put lives at risk. Backup generators are the best way to ensure that you have an uninterrupted supply of electricity, all year round. If your freezer is left without power, or you are left with no heating or lighting during winter, outages can have dire consequences. Homeowners are not the only victims of brownouts; any retailer storing perishable goods in freezers risks losing thousands of dollars worth of goods, disappointing their customers.

Of course, backup generators have many other uses, and businesses use backup generators to power tools and appliances in places where there is no mains electricity. Portable generators are a necessity for motor-home owners and yacht enthusiasts, allowing them to enjoy all of the comforts of home.

Backup generators are available in a wide array of sizes, capacities and models, so selecting the best type for your needs can be difficult. However, from the room sized behemoths used to provide hospitals with power, to small models that can easily fit in a car, generators all work upon the same principle. Backup generators use a gas, propane, or diesel powered motor to turn a dynamo and produce electricity, and choosing the best is simply a matter of balancing capacity and reliability with budget.

The cheapest and easiest option is to buy a small portable backup generator, which can be unobtrusively stored, easily available when needed. Small portable generators provide enough wattage to power a few appliances, so they are useful as a temporary solution. For example, if the power goes down, portable generators provide enough power to stop the freezer defrosting and to power the lights.

There are some disadvantages with this type: they need refueling frequently, for which they need to be shut off, and they do not start automatically when the power supply is interrupted. If you need a backup generator that will automatically start, then a permanent backup generator is the only viable option.

For infrequent use, portable generators are extremely useful and find many uses in business, from building contractors to mobile fast-food vans. The smallest models are gas/petrol operated, whilst larger portable generators generally use diesel power. Diesel portable generators are very durable, cheaper to run, and require less maintenance. However, they are usually more expensive, heavy and cumbersome than their gas operated counterparts.

Permanent back-up generators are a better option for homes or businesses with many power hungry appliances, or in areas where blackouts and brownouts are extremely common. Permanent generators vary in size, from a small back up generator that sits in the corner of a garage, to the huge generators used to back up the power supply in hospitals and nursing homes. Permanent backup generators are usually diesel, rather than gasoline powered, because of their durability and fuel efficiency.

Where low noise is important, gas powered back up generators are a superb option, and most use a bi-fuel system, allowing them to run on natural gas or propane. Gas powered generators are more expensive and less durable, and the gas needs to be stored in a secure, safe place. However, permanent back up generators are far more fuel-efficient than portable models and require less time between refills. Importantly, permanent back up generators can be fitted with an auto-start switch, kicking the motor into life if the power supply fails.

Most backup generators have power output measured in horsepower, but that is not really important. The figure that you need to know is the maximum output in watts, because this tells you how many electrical appliances you can run off a backup generator. Most generators produce between 2000 and 7000 watts, which is enough for most normal applications. To find out what wattage you need, look at the wattage of every appliance that you will be using and add them together; this figure is written on the appliance or within the accompanying literature.

This is not the only factor, however, as certain motor-driven tools and appliances need a ‘start up’ wattage. For a few seconds, they draw more power, so you need to leave a little spare capacity for this. Such appliances include most power tools, refrigerators, and freezers, and they require 1.5 to 2.5 times the normal running wattage.

A back up generator must be sited away from the fuel source, and in a well-ventilated area. You must always switch off the generator before refilling, so buy one with a large tank capacity if uninterrupted operation is important. Finally, read all of the accompanying literature before operation and seek professional help if there is anything that you are not sure about.

Selecting the best backup generator for the job can be a little daunting, but doing your homework and understanding your specific needs will help. Estimate the likely wattage you will need, the preferred fuel type, and whether you need a permanent backup generator or a portable generator. This will ensure that you spend your money wisely and buy a backup generator that gives years of uninterrupted service.