A Guide for Commercial Customers Navigating Their Electric Bills
Electric bills can feel like a puzzle, especially for commercial customers who face a mix of charges that go far beyond simple energy use. One of the most important (and often misunderstood) components is the demand charge. If you’ve ever wondered why your bill spikes even when your total energy use hasn’t changed much, demand charges are likely the reason.
Let’s break down what they are, why they matter, and how your business can take control of them.
Energy Charges vs. Demand Charges: What’s the Difference?
Commercial electric bills typically include two major components:
1. Energy Charges (kWh)
This is the part most people are familiar with. It reflects the total amount of electricity your business consumes over the billing period. Think of it like the odometer on a car: it measures how far you’ve driven.
2. Demand Charges (kW)
Demand charges measure the highest rate at which your business uses electricity at any moment during the billing cycle. Instead of tracking how much energy you use, demand charges track how fast you use it.
A helpful analogy: If energy charges are the miles you drive, demand charges are the peak speed you hit during the trip.
What Exactly Are Demand Charges?
Demand charges are based on your facility’s maximum power draw, usually measured in 15‑minute intervals. Utilities must build and maintain enough infrastructure (transformers, wires, substations, etc.) to serve your highest possible load, even if you only hit that peak once a month.
So if your business has one moment of very high usage—say, when HVAC systems, industrial equipment, and lighting all kick on at once—that single spike can set your demand charge for the entire billing cycle.
This is why two businesses that use the same total energy can have very different bills.
How Peak Hours Influence Demand Charges
Many utilities apply higher demand charges during on‑peak hours, when the grid is most stressed. These hours vary by region but often fall during weekday afternoons or early evenings.
During peak periods:
- Your demand is more expensive
- Short bursts of high usage can dramatically increase your bill
- Even a single equipment startup can set your monthly peak
Understanding your utility’s peak schedule is essential. If you can shift certain operations to off‑peak hours, like running heavy machinery early in the morning or late at night, you can significantly reduce your demand charges.
How to Get a Handle on Your Demand
Here are a few practical steps businesses can take:
- Review your utility bill to identify your peak demand each month
- Analyze your load profile to see when spikes occur
- Stagger equipment start‑ups to avoid simultaneous surges
- Shift flexible operations to off‑peak hours
- Upgrade to more efficient equipment to reduce overall load
But one of the most powerful tools for managing demand charges is increasingly accessible and cost‑effective: battery energy storage.
How Battery Energy Storage Systems Reduce Demand Charges
Battery energy storage systems (BESS) can dramatically lower demand charges by smoothing out your facility’s load profile.
Here’s how it works:
- During times of high demand, the battery discharges to supply part of your load
- This prevents your facility from drawing a large spike of power from the grid
- Your “peak demand” for the month stays lower, reducing the demand charge
- During low‑cost or off‑peak hours, the battery recharges
This strategy, known as peak shaving, can reduce demand charges by 20–50% or more, depending on your load patterns and utility rate structure.
Beyond cost savings, batteries can also provide backup power, support sustainability goals, and improve resilience during outages.
Final Thoughts
Demand charges are one of the biggest drivers of commercial electricity costs, but they’re also one of the most controllable. By understanding how your peak demand is measured, and how your operations influence it, you can take meaningful steps to reduce your bill.
And with technologies like battery energy storage becoming more affordable, businesses now have powerful tools to manage demand proactively rather than reactively.
If you’d like help analyzing your facility’s demand profile or exploring whether a battery system makes sense for your business, the EPC Energy team is ready to help!