A presentation at Choosing Between Multiple Small Generators vs One Large Generator in in Australia by How to Choose the Right Diesel Generator for Your Needs
When you are staring at a massive power requirement for a new job site, a remote farm, or a backup system for your business, you eventually hit a fork in the road. Do you buy one massive, heavy-duty “prime” generator that can handle everything at once, or do you set up a fleet of smaller units working together? It’s the classic “eggs in one basket” dilemma. If you go too big, you might be wasting fuel; if you go too small, you might lack the “grunt” needed for heavy machinery. If you are currently weighing up your options and need to see what’s available in the professional market, you can buy from here to get a feel for the different scales of industrial equipment. But before you open your wallet, you need to look past the sticker price and think about the logistics of how your power is actually going to be used every day.
This isn’t just about total kilowatts; it’s about redundancy, fuel efficiency, and what happens when things go wrong in the middle of a project.
There is a reason why large-scale industrial sites often lean toward one massive generator. It’s the simplest solution on paper. You have one engine to maintain, one fuel tank to fill, and one control panel to monitor.
Initial Cost Efficiency: Generally speaking, buying one 500kVA generator is cheaper than buying five 100kVA generators. You aren’t paying for five trailers, five enclosures, and five sets of control electronics. If your budget is tight upfront, the “one big unit” approach usually wins.
Simple Maintenance Logistics: When it’s time for a service, you only have one oil filter to change and one set of injectors to check. For a business that doesn’t have a dedicated mechanical team, managing a single asset is far less of a headache than keeping track of a fleet.
Handling Massive Surge Loads: If you are starting huge electric motors or industrial pumps, you need “mass.” A large generator has a massive alternator that can handle a giant “inrush” of current without the voltage dropping or the engine stalling. Small units, even when linked together, sometimes struggle with that initial “hit” compared to one big, heavy-duty flywheel.
The biggest risk with one large generator is that it is a single point of failure. If a $2$ dollar sensor fails or a fan belt snaps on your one big machine, your entire site goes dark. In a remote location, that could mean days of downtime while you wait for a technician to drive out with a spare part.
When the power goes out, the “savings” you made by buying one unit disappear instantly in lost labor and missed deadlines. This is the primary reason why many critical operations—like hospitals, data centers, and remote mines—avoid the “single big unit” strategy.
In the last decade, technology has made it incredibly easy to “parallel” generators. This means you connect multiple smaller units together so they act as one big power source. This approach offers a level of flexibility that a single machine just can’t match.
Redundancy is King: If you have three 100kVA generators running your site and one fails, you still have 200kVA of power. You might have to turn off the non-essential gear, but your lights stay on, your comms stay up, and your critical systems keep moving. That “buffer” is worth its weight in gold during a crisis.
Scalability: Maybe today your project only needs 100kVA, but in six months, it will need 300kVA. If you start with smaller units, you can just add another one to the chain as your needs grow. With a single big unit, you’re stuck with whatever you bought on day one.
Ease of Transport: Moving a 500kVA generator requires a specialized truck and often a crane. Moving three 150kVA generators can be done with standard 4WDs and trailers. If you move sites frequently, the smaller units are much more mobile and easier to position in tight spaces.
This is where the math really starts to favor multiple units. Diesel engines are most efficient when they are running at $70%$ to $80%$ of their capacity. If you run a massive generator at $10%$ load (for example, at night when only the security lights are on), you are burning a ridiculous amount of fuel for almost no output.
Worse yet, running a big diesel engine at low load causes “wet stacking”—unburnt fuel builds up in the cylinders and gums up the engine. This leads to high maintenance costs and a shorter engine life.
With a paralleled system, the “brain” of the setup (the controller) watches the load. If the demand is low, it shuts down two of the three generators. The remaining unit runs at its optimal, fuel-efficient $80%$ load. When the sun comes up and the crew starts using heavy tools, the other units automatically fire up and rejoin the grid. You end up saving thousands of dollars in fuel over the course of a year.
When you have a single generator, “maintenance” means “blackout.” You have to shut down the whole site to change the oil. With a multiple-generator setup, you can perform “rolling maintenance.”
You take one unit offline, service it, and put it back in the chain while the other units keep the site powered. For businesses that operate 24/7—like 24-hour service stations, cold storage, or non-stop manufacturing—this is the only way to operate without losing money during every service interval.
The choice ultimately comes down to your “risk tolerance” and your “load profile.” Go with One Large Generator if: Your power demand is constant (it doesn’t drop much at night), you are on a strict initial budget, and you have easy access to a backup power source or quick mechanical support if things go wrong.
Go with Multiple Small Units if: Your power needs fluctuate wildly throughout the day, you are in a remote area where a breakdown would be a disaster, or you need the ability to grow your power capacity over time without replacing your entire system.
Summary: Reliability vs. Simplicity
At the end of the day, a single large generator is a simpler, cheaper tool, but a fleet of smaller units is a more resilient, smarter system. If you’re running a backyard project, go big and simple. But if you’re running a business where “time is money,” the redundancy and fuel savings of multiple units usually pay for themselves within the first two years of operation.
Before you make a final call, it is worth doing a “Load Audit” of your site. Take note of your peak demand (when everything is running) and your idle demand (at night). If the gap between those two numbers is huge, multiple small units are almost certainly the better investment.
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