A commercial electric bill is not one charge. It is several different charges, computed different ways, and solar affects each of them differently. Businesses that understand the distinction get useful solar proposals. Businesses that do not tend to get proposals built on the single number printed at the bottom.
This is a practical guide to reading your own bill before anyone designs a system for you.
The Two Charges That Matter Most
| Charge | What It Bills | Why It Matters |
|---|---|---|
| Energy charge | Kilowatt-hours consumed, priced by time period | This is what solar addresses directly. Every kilowatt-hour the array supplies is one you do not buy. |
| Demand charge | Your single highest rate of draw during the billing period, in kilowatts | Set by one brief peak. Solar reduces it only when the array happens to be producing at that moment. |
A business can consume a modest number of kilowatt-hours and still carry a substantial demand charge, if its load is spiky. Another can consume steadily all day and carry a comparatively small one. The bills look similar at the bottom and call for very different designs.
Alongside these sit non-bypassable charges and various fixed and public-purpose components. These are worth knowing about mainly because they do not disappear with solar — no system takes a commercial bill to zero, and any proposal implying otherwise is worth a second look.
Time-of-Use Periods
Commercial customers are on Time-of-Use rates, which price the same kilowatt-hour differently depending on when it is consumed. Periods are generally divided into peak, part-peak and off-peak, with different definitions and different prices in summer than in winter.
The practical consequence is that when your consumption occurs matters as much as how much of it there is. Two facilities using identical annual totals will see different bills if one runs mostly in peak hours and the other does not.
Solar production follows the sun rather than the rate schedule, so the overlap between your heaviest-priced hours and your strongest production hours is one of the most important numbers in a system design. It is also one that a proposal built from a single annual total cannot know.
Interval Data: The Document That Actually Matters
Your monthly bill is a summary. Behind it, your utility records consumption at fixed intervals throughout the day, every day. That interval data is the real picture of how your building uses electricity, and as the account holder you can request it.
It answers the questions that determine system size:
- What does your load look like hour by hour on a typical operating day?
- How much of your consumption falls inside daylight hours?
- Where and when do your demand peaks actually occur?
- How different are your weekdays from your weekends, and your summer from your winter?
A design built on interval data can be sized to the load. A design built on twelve monthly totals is, at best, an educated guess wearing a proposal cover.
Where Solar Helps, and Where It Does Not
| Bill Component | Effect of Right-Sized Solar |
|---|---|
| Daytime energy charges | Strong and dependable. This is solar’s home ground. |
| Evening and overnight energy | None without storage. The array is not producing. |
| Demand charges | Partial and not guaranteed. A cloudy interval or an off-hours equipment start can set the monthly peak regardless of the array. |
| Fixed and non-bypassable charges | None. These remain. |
This table is the reason we are careful about what we promise. Solar is excellent at the thing it is good at. Presenting it as a solution to the whole bill sets up a disappointment that shows up in month two.
What to Ask For Before You Get a Proposal
Three documents let any competent contractor do real work:
- Twelve consecutive months of bills — enough to capture seasonal variation.
- Your current rate schedule — printed on the bill. It governs how everything above is priced.
- Interval data — requested from the utility for the same period.
If you are talking to several contractors, give them all the same three documents. Differences in the proposals will then reflect differences in design judgment rather than differences in what each one guessed.
What This Means for Commercial Customers
Every successful solar project starts with understanding your energy use. Before recommending a single solar panel, we evaluate your utility bills, interval energy data, operating schedule, electrical service, available tax incentives, and long-term business objectives.
That evaluation frequently turns up things worth doing that are not solar at all — load management, equipment modernization, a service upgrade, efficiency improvements. Sometimes one of those produces a better return per dollar than adding panels would. We would rather tell you that than sell you the array.
Our Design Philosophy
Our first objective is not determining how many solar panels fit on your roof. It is understanding how electricity moves through your facility.
The bill is where that understanding starts.
Request a free consultation and we will read yours with you.