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Perfect Fit: How to Choose the Right Size Diesel Generator

Perfect Fit: How to Choose the Right Size Diesel Generator

Good morning readers, Robert here. I have over ten years of experience working with diesel generators and energy systems. Throughout my career, I’ve learned how crucial it is to size your diesel generator correctly to meet your power needs reliably and efficiently. This comprehensive guide will share my knowledge to help you pick the perfect generator for your specific requirements.

Determining Your Power Requirements

The first step is calculating your power requirements for now and the future. Before we get into specifics, here are some diesel generator facts: diesel gensets became popular in the 1930s when diesel engines were recognised for reliability and fuel efficiency. Now, they are ubiquitous worldwide!

When determining the load that your generator will need to handle, there are two central values to calculate:

  • Total Running Watts refers to how much power your equipment uses actively. Take inventory of everything you plan to connect to the generator simultaneously and add their rated wattages.
  • Largest Starting Surge: When starting up, specific devices like air conditioners and refrigerators require short spikes of extra power. Note down the highest surge wattage in addition to the total running wattage.

It is also wise to factor in future expansion. Planned additions or replacement of equipment may increase your power requirements. I generally recommend adding at least 30% as a safety net.

Sizing a Diesel Generator

Prioritising Your Loads

During extended power failures, you should be strategic about what gets connected to your limited backup power supply. As you make your load list, mark each device as critical, essential or non-essential.

Here are some examples for each category:

  • Critical: Life safety equipment, medical devices, emergency lighting
  • Important: Refrigeration machines needed for business continuity
  • Non-essential: Entertainment and convenience electronics

This classification will guide you if you ever need to shed loads.

Diesel Generator Basics

Before choosing a generator model, let’s go over some terminologies:

  • Portable Generators: Compact generators meant for temporary use. Easy to move and have limited output capacity.
  • Standby Generators: Permanently installed units that automatically supply backup power to your building in case of outages.

Now for the specifications:

  • Output power is denoted in:
    • Watts (W) - units of natural electrical power
    • Volt-Amps (VA) - units of apparent power
  • When fuel consumption is denoted in litres per hour (lph), this specifies the fuel used when operating at capacity, i.e. putting out maximum rated output.

Standby units offer more output power options. Generators must be sized according to your peak power needs, not average consumption.

Sizing Your Diesel Generator Correctly

As highlighted earlier, accurate load calculation is critical to properly sizing your backup generator. Both undersized and oversizing can cause problems:

Consequences of under-sizing

  • Insufficient power - leading to outages
  • Generator overload - risking damage

Consequences of over-sizing

  • Higher upfront and operating costs
  • Lower fuel efficiency and excessive emissions

The best practice is to choose a generator sized to about 60-80% of its rated capacity under a peak load scenario.

Here is a step-by-step process:

1. Determine Total Startup Surge Watts

(Highest starting power requirement)

2. Determine Total Running Watts

(Power needed for simultaneous operation of all loads)

3. Select the appropriate standby generator size

  • Should exceed total startup surge watts
  • And provide at least 60-80% buffer for total running watts at rated capacity

If this seems complicated, you can always consult a qualified sizing specialist. Many generator retailers also offer assistance to their customers for free.

Factors Impacting Diesel Genset Output

Note that various external factors impact the generator’s power output capacity:

  • Altitude: Thinner air causes lower combustion efficiency
  • Temperatures: Extreme hot or cold affects engine performance
  • Fuel quality: Impure or low-grade diesel lowers genset capacity

Reputable generators like Himoinsa appropriately derate their capacity ratings to account for these variables.

Get the right sized diesel generator

Installation and Placement

Proper installation is essential not only for performance but also safety. Always employ a licensed electrical contractor to connect your standby generator system. Some key guidelines:

Indoor vs. Outdoor

Outdoor metal enclosures provide maximum protection against sound, fumes and fire hazards. Only small portable gensets may be approved for indoor use.

Physical Security

Your generator can become a target for theft if isolated or openly accessible. Keep it fenced-in or locked inside a ventilated room.

Weather Protection

If installing outdoors, position the generator with weatherproof metal enclosures under an awning or roof overhang to prevent direct exposure to rain, snow and other elements.

Fumes and Noise

Exhaust must vent safely away from doors, windows, or intake vents. Also, ensure the genset noise does not bother neighbours.

Consult your local regulatory codes for any requirements regarding placement, enclosure, noise limits, etc. Proper permitting is mandatory.

Maintaining Your Diesel Generator

Once properly installed, be sure to maintain your generator meticulously. This dramatically impacts its performance and lifespan.

Here is my 5-point maintenance plan:

  1. Keep batteries charged - Allowing batteries to discharge damages them and can prevent starting
  2. Change oil, filters, and spark plugs - Follow the manufacturer's service schedule
  3. Inspect and clean components - Fix loose connections, debris build-up, etc.
  4. Test under load - Detect problems before an actual emergency
  5. Add fuel stabilisers - Prevent algae growth and separation during storage

Note that larger generators require more frequent maintenance activities compared to smaller ones. So, size does impact the care your generator will need.

Being diligent about maintenance lets your generator operate smoothly for decades, even in harsh environments - as some of the oldest working models still in use demonstrate.

Proper maintenance also optimises diesel consumption. This brings me to my next topic, which especially interests readers concerned about their carbon footprint…

Innovations in Sustainable Power Generation

The first diesel generator was patented in 1895 - over 125 years ago! The basic premise remains similar, but technology has come a long way since then…

Rising fuel prices and environmental awareness have spurred innovations targeted at efficiency and sustainability:

  • Clean diesel technology - Drastically reduces emissions using ultra-low-sulphur fuel and advanced catalysts. Emissions can exit via conventional exhaust now!
  • Alternate fuels - Renewable biodiesel, ethanol, etc., can replace fossil diesel. Dual-fuel generators allow switching between biodiesel and conventional diesel based on availability and prices.
  • Solar hybrids - Integrating photovoltaic panels and connecting batteries to the output allows stored solar energy to assist the engine. This can cut fuel consumption by over 50%!
  • Telematics monitoring - Smart dashboard insights into generator performance enable high efficiency. Operators can diagnose problems instantly, and predictive analytics optimises maintenance.

So, while diesel generators are renowned for their longevity, integrating modern innovations can make them even more reliable plus environmentally sustainable!

I will continue sharing the latest trends as we strive to balance performance with our planet’s health during rapid technological change. Please join me in exploring this ever-evolving generator landscape.

This guide has helped you gather all the background needed to pick the perfect diesel generator. Please drop any other questions in the comments section below!

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