Interval data is the record of how much power your site drew in each short measurement period, usually every fifteen or thirty minutes, for as long as the utility has kept it. A monthly bill is that record collapsed into two or three numbers.
Almost every question worth asking about a commercial electricity bill lives in the part that gets collapsed. That is the case for wanting it. The case against wanting it is that a good number of questions are answered by the bill alone, and going to get interval data first is a way of postponing a decision you could already make.
Which questions the bill already answers
Do these first, because they are free and they settle a lot of cases.
Is there a demand charge, and how big is it? The bill says so. If the delivery portion has no line priced in dollars per kilowatt, the whole peak-management category does not apply to you and interval data will not change that.
Did usage rise or did price rise? Twelve bills compared against the same month a year earlier answer this. Interval data is not needed and does not help.
Is your demand stable or volatile month to month? Write the billed kilowatts from twelve bills in a column. Stable means your peak is the ordinary shape of your operation. Volatile means something identifiable is setting it. That distinction decides whether anything can be done, and it comes off the bill.
If the answer to the first question is no, stop. You have saved yourself a data request.
Which questions genuinely require it
Three, and they are the ones with money attached.
How far your peak sits above your second highest interval. This caps what any peak reduction can recover, and it cannot be derived from a bill because the bill only contains the top number. Remove your highest qualifying interval and the next one becomes your billed demand. The saving is the gap.
What actually set the peak. A bill tells you the peak was 242 kilowatts. It does not tell you it happened at 8:30 on a Tuesday morning in March when three things started together. Only the interval record does, and knowing which three things is the difference between a fix and a guess.
Whether a battery, a schedule change or solar would have paid. The one that matters most, and the one most often answered with a projection instead of a measurement. Run the intervention against your recorded intervals and you get what it would have done. Run it against a class-average profile and you get what it would have done for a business that is not you.
What we can do about Ameren Illinois, stated plainly
We hold a production data connection to ComEd. Phantom Grid is one of three providers listed in ComEd's production Connect My Data directory, and for residential accounts, with the customer's authorization, we retrieve the interval record directly rather than asking anyone to export a file. For ComEd business accounts the tariff routes it differently and the customer passes the file on themselves.
We hold no working connection to Ameren Illinois today. We have begun their third party registration, and the stated lead time is several weeks, so this may change. What has not happened yet is the part that matters: we have not received a file from them, and we are not going to describe a request procedure we have not run end to end. That would be a page written from a website rather than from experience, which is the thing we criticise other people for. When it works, this page will say so and will say when.
What we can say is the part that is a matter of Illinois law rather than of any utility's product: your usage data is yours, and a utility serving you is obliged to make it available to you. The request is yours to make. Ask Ameren Illinois for your interval or load profile data for your account, name the period you want, and ask what formats they provide it in.
What to ask for, so the file is usable when it arrives
Requests come back wrong often enough that this is worth being specific about.
The measurement interval. Fifteen minutes or thirty. Hourly data hides short peaks, and short peaks are what set demand charges.
A full twelve months at minimum. Seasonality is the point. Four months of data cannot tell you whether your summer peak is your annual peak.
Timestamps with the time zone and daylight saving handling stated. This sounds pedantic and it is the single most common reason an analysis comes out wrong. An hour shifted in spring or repeated in autumn moves intervals in and out of a billed window.
Every meter, if the site has more than one. How multiple meters combine into a billed demand is a tariff question, and one meter's file cannot answer it.
The units. Kilowatts, kilowatt hours per interval, or both. Mixing them up scales an answer by four.
The honest position on whether you need it
If your bill has no per-kilowatt charge and your usage is stable, you do not need interval data to make a decision. Say no to anyone who tells you otherwise before establishing that.
If your bill has a meaningful demand charge and your billed kilowatts jump around, you cannot make an honest decision without it, and every proposal you receive that does not contain the gap between your top two intervals is a projection wearing the clothes of a measurement.
Is my Ameren Illinois interval data mine to request?
Your usage data is yours, and the utility serving you is obliged to make it available to you. We have begun Ameren Illinois's third party registration but have not yet received a file through it, and we will not describe a request process we have not run end to end, so ask them directly what they provide and in what format.
Do I need interval data to reduce my electricity bill?
Only for some questions. Whether a demand charge exists, whether usage or price moved, and whether your peak is stable or volatile are all answerable from twelve bills. What your peak cost you and what an intervention would have saved are not.
What resolution should I ask for?
Fifteen or thirty minute intervals, twelve months minimum, with timestamps that state the time zone and how daylight saving is handled. Hourly data hides the short peaks that set demand charges.
Can Phantom Grid pull my Ameren Illinois data automatically?
Not today. We hold a production connection to ComEd and are listed in ComEd's production Connect My Data directory. Ameren Illinois third party registration is under way and takes several weeks, but no file has come through it yet, and we would still need a real bill with matching interval data to establish the billing mechanics honestly.