Getting the size of your generator right isn’t a minor detail in a backup power project—it’s the most important part of whether the system can do its job. A generator that’s too small quits the instant you turn it on. One that’s too big costs more to buy, more to install, and more to run for years afterward.
If your Denver area business is considering a new backup generator, there’s steps you can take to ensure it doesn’t cost more than it should.
Why Guessing Doesn’t Work
It’s tempting to size a generator the way you’d size almost anything else: look at the building’s square footage, pick something that seems “about right,” and move on. Unfortunately, that approach almost never lines up with reality.
A 10,000-square-foot office and a 10,000-square-foot manufacturing floor draw wildly different loads, and even within the same building, not every piece of equipment needs to run during an outage.
Undersizing shows up immediately. Breakers trip, motors struggle to start, and sensitive electronics take damage from a generator straining under a load it can’t support.
Oversizing is quieter but just as costly. A generator running well below its rated capacity operates less efficiently, can suffer from wet stacking (a buildup of unburned fuel in the exhaust system), and ties up capital that didn’t need to be spent.
Start With a Real Load Calculation
Proper generator sizing starts with a load calculation, not an estimate. This means identifying every piece of equipment that needs power during an outage—HVAC systems, refrigeration, servers, lighting, security systems, production machinery—and calculating both the running wattage and the starting wattage for each.
That second number matters more than most people expect. Motors, compressors, and pumps draw a surge of power when they first start, sometimes two to three times their running load.
A generator sized only for running watts will stall or shut down the moment one of those big pieces of equipment kicks on. This is a common failure point in facilities with walk-in coolers, HVAC compressors, or industrial machinery, all of which have significant startup draw.
Decide What Actually Needs Backup
Not every circuit in a building needs to be on the generator. Part of sizing correctly is deciding, in advance, what’s essential during an outage and what can wait.
A restaurant might prioritize refrigeration and a few lights over decorative signage. A medical office will prioritize different systems than a warehouse. And an industrial facility might need to keep specific production lines running while others can safely sit idle.
This step often gets skipped, and it’s the reason so many generators end up oversized. Businesses specify a generator for the whole building rather than for the loads that genuinely matter during an emergency, then pay for capacity they’ll rarely use.
Plan for Where the Business Is Headed
Sizing shouldn’t only reflect the building as it exists today. If new equipment, additional square footage, or expanded production capacity is realistically on the horizon, that should factor into the calculation.
A generator sized with zero room to grow can become a bottleneck the moment the business adds a new piece of equipment. That doesn’t mean padding the size significantly “just in case,” but rather building in a reasonable, calculated margin based on actual plans, not guesswork.
Why Fuel Type and Application Matter Too
Sizing isn’t the only variable, but it interacts with almost every other decision in the process.
Standby generators, which run on natural gas or diesel and are permanently installed, are sized differently than portable units meant for short-term or partial coverage.
Denver’s climate and elevation can also affect generator performance, since engines and cooling systems behave differently at altitude than they do at sea level. A sizing calculation that doesn’t account for these factors can look accurate on paper and still underperform in practice.
Get the Calculation Done Right the First Time
Generator sizing isn’t a place to cut corners or rely on rules of thumb. An accurate load calculation, a clear picture of essential versus non-essential circuits, and a realistic view of future needs are what separate a backup power system that performs when it counts from one that becomes an expensive underperformer.
MV Power Solutions works with Denver businesses to calculate load requirements accurately and design backup power systems sized for the way a facility actually operates, not just its square footage.
If your business is considering a generator, a proper sizing assessment is the first step worth getting right. Contact MV Power Solutions to learn more about adding a generator or electrical backup system to your Denver business.