A generator size should be roughly twice as powerful as your inverter. This will allow it to charge the battery and power your house. For instance, if your inverter is 4,000 watts, you require a generator that is at least 6,880 watts. In this situation, an 8kW (8,000-watt) generator would work well. If you are in a high location such as a mountain, your generator will lose power—at about 3% for each 1,000 feet. So, you may need a slightly larger one.

Why Bigger Generators Can Be Helpful

If you have large equipment such as air conditioners or welders, you want a larger generator. Some do the job with a 12kW or 14kW generator with a 4,000-watt inverter. Larger generators consume more fuel, but they provide you with more power and run longer.

Can You Use a Small Generator?

Yes, but you might have to reduce how much power the battery charger draws. Most battery chargers allow you to adjust settings to suit the generator. It’s also crucial to equal the voltage of the generator with the inverter. If a generator is 120 volts, the inverter must be 120 volts. Some specific inverters will operate on a different voltage, but you need to reduce the charge rate.

Selecting the Correct Fuel Type

Generators may be powered by diesel, propane, or natural gas. Diesel generators are more durable and fuel-efficient but are more expensive. Propane and natural gas generators are less expensive and are popular in off-grid residences. Propane is more suitable for remote locations since it’s simpler to locate. Certain generators have the ability to switch between propane and natural gas.

Warranty and Operating Two Generators Simultaneously

Not all generators are designed for off-grid applications, so read the warranty before purchase. Some have only an 18-month or 1,000-hour guarantee. If you require more power, two generators can be linked together with a special module to boost output.

Connecting a Generator to a Solar System

For solar installations, a generator should have a “2-wire start” capability. This allows the generator to start up automatically when the battery is low. Some generators have electric start but no 2-wire start, and they will not be compatible with solar installations. Be sure to verify before purchase.

Generator Speeds and Efficiency

Generators run at different speeds. Those that run at 1800 RPM (rotations per minute) last longer, are quieter, and use less fuel, but they cost more. Generators that run at 3600 RPM are cheaper and more common in off-grid systems. Some brands don’t make 1800 RPM generators smaller than 24kW, so you may need to look for other options.