15 October 2024

Generators are either required to be a prime power source (either full time or temporary) or an emergency backup power source. If you have done a search on the internet for  ‘what kind of generator do I need for a power outage‘ you have likely been met with a whole host of different types, sizes, makes and models. So, for power outages,  what is the best type of generator?  It depends on factors like the duration of the outage, the size of the area to be powered, and the specific appliances you need to run. Here are some common generator options for power outages:

1. Portable Generators

• Best for: Short-term outages or powering essential appliances.
• Capacity: Usually around 3,000 to 10,000 watts.
• Fuel: Gasoline, petrol, or diesel.
• Pros:
  • Easy to move and set up.
  • Can power multiple essential items (refrigerator, lights, etc.).
  • Lower upfront cost.
• Cons:
  • Limited run time based on fuel availability.
  • Need to be manually connected.
  • Can be noisy and require regular refueling.

2. Inverter Generators

• • An inverter generator is a type of generator that produces clean and stable electricity by converting raw AC power (alternating current) into DC power (direct current) and then inverting it back to AC power. This process ensures that the power output is smoother and has fewer fluctuations, making it ideal for powering sensitive electronics, like laptops, smartphones, and other devices that could be damaged by power surges.
• • Best for: Sensitive electronics during short outages.
  • Capacity: 1,000 to 4,000 watts.
  • Fuel: Gasoline or propane.
  • Pros:
    • Produces clean, stable power suitable for electronics.
    • Quieter and more fuel-efficient than portable generators.
  • Cons:
    • Less powerful, so they can’t run multiple large appliances simultaneously.

3. Diesel Generators

• Best for: Large facilities such as factories, warehouses, hospitals, data centers, and construction sites.
• Capacity: 2  kVA – 4,000 kVA +
• Fuel: Diesel
• Pros:
  • Can automatically turn on during an outage.
  • Industrial and commercial operations that require continuous or large-scale power.
  • Remote locations where there is no access to grid power.
  • Critical applications where uninterrupted power is essential, such as hospitals or data centers.
  • Heavy-duty machinery and tools, especially in construction and agriculture.
  • Diesel generators are the go-to solution when reliable, heavy-duty power is needed for long durations, or in situations where fuel availability and efficiency are crucial.
  • Diesel generator engines are built to last, they are robust and are designed to be in harsh working environments.
• Cons:
  • Higher upfront cost.
  • Installation is more complex and requires professional assistance.
  • Size and weight: Diesel generators are larger and heavier, making them less portable.

How to work out what size generator is right for you:

First things first, in order to work out what type or size of generator is right for you, you’ll need to consider your total power requirements and account for the types of equipment or appliances you’ll be running. Here’s a step-by-step guide to help you calculate the right generator size:

1. List All Appliances and Equipment You’ll Power

• Identify the devices, appliances, and equipment that need power during an outage or regular use. Include everything from essential items (lights, refrigerator, heating) to heavy machinery or systems (HVAC, industrial equipment).

2. Determine the Power Requirements of Each Item

• Look for the power ratings (usually in watts or kilowatts) on the appliances or in their manuals. Some items may list amps and volts, and you can use the following formulas to calculate the power in watts:
  • Watts = Amps × Volts
  • For example, if an appliance uses 10 amps and runs on 120 volts, the power requirement would be:
    • 10 amps × 120 volts = 1,200 watts (or 1.2 kW)

3. Identify Starting vs Running Wattage

• Starting (Surge) Watts: Some equipment, especially those with motors (refrigerators, air conditioners, power tools), need extra power to start. This is the peak wattage when the device first starts up, which can be 2-3 times higher than its running wattage.
• Running (Continuous) Watts: This is the steady amount of power the appliance uses once it is running.
• Make sure to account for both starting and running wattage when calculating your total power needs.

4. Add Up the Total Power Needs

• Add up all the running wattage of the appliances and equipment you want to run simultaneously.
• Account for surge watts: Ensure the generator can handle the higher surge wattage of appliances that require it (e.g., refrigerators, air conditioners, pumps).

5. Consider Additional Factors

• Future growth: If you expect to add more equipment or appliances in the future, consider getting a generator with slightly more capacity than your current needs.
• Critical loads: Prioritize which appliances are essential and focus on those if budget or space is limited.
• Power factor (for industrial/commercial applications): For larger or industrial loads, you may need to factor in the power factor (usually around 0.8 for most appliances). This is important when calculating kVA (apparent power) vs. kW (real power). The formula is:
  • kVA = kW ÷ Power Factor

6. Convert Watts to kVA (for Larger Generators)

• For larger generators, the size is typically measured in kVA rather than watts or kilowatts. To convert:
  • kVA = kW ÷ Power Factor (The power factor is usually 0.8 for most commercial loads.)
  • Example: If your equipment requires 10 kW of power and the power factor is 0.8:
    • 10 kW ÷ 0.8 = 12.5 kVA

7. Choose a Generator with Sufficient Capacity

• Residential or Small Business: For home backup, a generator of 5 to 20 kVA is typically sufficient.
• Commercial or Industrial: Larger facilities may need generators ranging from 50 kVA to several thousand kVA depending on the size and the critical equipment.
• It’s always better to choose a generator that has a slightly higher capacity than your immediate needs to avoid overloading.

Example Calculation:

Let’s assume you need to power:

• Refrigerator: 1,200 watts (running), 2,200 watts (starting)
• Air conditioner: 1,500 watts (running), 3,000 watts (starting)
• Lights: 500 watts
• Computer: 300 watts

Total running watts:

• 1,200 (refrigerator) + 1,500 (AC) + 500 (lights) + 300 (computer) = 3,500 watts (3.5 kW)

Highest starting wattage:

• Refrigerator: 2,200 watts (surge) – since this is the highest, make sure your generator can handle it.

Recommended generator size:

• A generator capable of handling 3,500 running watts and at least 2,200 surge watts would be needed. In this case, a 4.5 to 5 kW (5-6 kVA) generator would provide enough capacity for this scenario.

Summary of Steps:

1. List appliances and devices.
2. Determine wattage (running and starting).
3. Add up total running and starting watts.
4. Convert to kVA (for larger generators).
5. Choose a generator with sufficient capacity.

If you would like help with a specific load calculation or recommendations for your application, please contact our friendly team who will be able to help.