Generators are used in many different ways – as a supplement to or backup for an alternative energy system, in emergencies when power lines are down, on the ranch, construction site, campground, beach – anywhere we want to have power and land lines are not accessible.

Sometimes one finds that having a generator as a component of the alternative power system is more important than previously thought, perhaps even a necessity. Cloudy periods occur, things break, occasional periods of overuse due to company, or the additional requirements of some projects such as in the shop or construction.  Having a generator is important; if sized correctly, they can really help the “charger” aspect of an inverter boost your battery up quickly, and in many cases are critical when it is necessary to bring the cells to equal potential in the battery system.  

The generators with the “brushless-type alternators are the most dependable and longest lasting, and one should also look for models that feature a “direct couple” between the engine and the alternator head.

Additionally, diesel powered units are often preferred to other fuel choices because or their overall economy. They consume far less fuel per hour than gas or propane units and generally require the least amount of maintenance.  As an added benefit, off-road diesel can be used at a lower cost. Important note: treat your fuel for winter storage so you aren’t trying to pour Jello into your generator.

The one thing we cannot do with our generators is get more power from them than their maximum output, so evaluating your needs and what equipment you wish to use at any one time is critical in deciding what size generator to purchase.

You want to keep in mind the maximum and rated output of the generator you intend to purchase. Maximum output is available to assist in motor starting only. The generator should NOT be operated at maximum load for any longer than 30 minutes or damage to the generator will result.

There are two types of loads; reactive and resistive.

Reactive load items such as pumps, drills, saws, air compressors, washing machines, air conditioners and fluorescent lights draw much more on startup and as a general rule use three times the normal run load during start up. For example, if a pump has a run rate of 600 watts, then 3 X 600 = 1800 watts in the calculated need for the pump.

Resistive load items include coffee makers, blow dryers, standard light bulbs, area heaters, actually any kitchen appliance that heats up.  A resistive load of 600 watts draws 600 watts consistently.

Be aware of the number and type of items you are using with your generator.  Appliances such as dishwashers use both the reactive load for the motor that sprays the water and pumps it out, and also a resistive load during the drying cycle. Both the washing machine and the dishwasher require hot water, calling on water pumps and hot water heaters. Managing what is operating at any one moment is critical for proper operation of your generator.

Review the power requirements of each of the items you wish to run. Calculating the proper run load requirements is the best way to determine your actual needs. Sizing your generator is basically the same as the first step in sizing any alternative power system.  We have provided a chart with many common items and average power requirements and a simple worksheet to assist you in this endeavor.

Other considerations to review prior to choosing your generator:

Normal operating altitude – Generator power will be reduced by 3.5% for every 1,000 feet above sea level.

Average ambient temperature – Generator power will be reduced 1% for every 10 degrees over 85 degrees.

Extension Cords – The extension cords must have adequate wire size for safety, and to prevent the loss of power as well as overheating. The smaller the gauge (AWG = American Wire Gauge), the greater the capacity of the cable; for example, 16 gauge wire has more capacity than 18 gauge wire does. Be particularly careful when using multiple extension cords to acquire your total length.