Why Your Ameren Bill Keeps Going Up (and What MISO Has to Do With It)
If you're an Ameren Illinois customer and you've been staring at your summer bills wondering what happened — you're not imagining it. Your bill went up somewhere between 18% and 22% last summer. That's $38 to $46 extra per month that didn't exist the year before.
Most people blame Ameren. And Ameren is partly responsible — they've been filing rate increase after rate increase with the ICC. But the biggest hit came from somewhere most customers have never heard of: MISO.
What Is MISO and Why Should You Care?
MISO — the Midcontinent Independent System Operator — runs the power grid for central and southern Illinois. Ameren doesn't generate its own electricity. It buys it through MISO's markets, and those costs get passed directly to you.
Every year, MISO holds a capacity auction. Utilities bid to secure enough power to keep the lights on during peak demand. In 2024, that auction cleared at $30 per megawatt-day. A reasonable number. The grid was stable.
In 2025, it cleared at $666.50 per megawatt-day.
That's a 22x increase in a single year. And every dollar of it landed on your bill starting June 1st.
Why Did the Price Jump 22x?
Two things collided.
Coal plants are shutting down faster than replacements are coming online. MISO's reserve margin — the cushion between how much power is available and how much people need — dropped from 6.5 gigawatts to 2.6 gigawatts in two years. That's not a comfortable cushion. That's a region running on fumes during a heat wave.
Data center demand is eating up what's left. I wrote about this in detail in my data centers post, but the short version: facilities that consume as much power as mid-size cities are being built across Illinois, and they're competing for the same limited supply your house runs on.
When supply is tight and demand is surging, auction prices explode. That's what happened.
The Delivery Side Is Getting Hit Too
The capacity auction is the supply cost. But your bill has two sides — supply and delivery.
Ameren has been filing delivery rate cases with the Illinois Commerce Commission almost continuously. The ICC granted a $48 million increase for electric delivery charges in late 2025 — less than Ameren asked for, but still a meaningful hit.
And an Ameren representative told regulators the company intends to file another rate increase request in 2026, regardless of what they were granted in the current case. That's not speculation — that's what they told the ICC on the record.
So supply costs are spiking from MISO auctions, and delivery costs are climbing from Ameren's own infrastructure spending. Both sides of your bill are going up, driven by different forces, with no mechanism to bring either one down.
What Does This Mean Going Forward?
The Citizens Utility Board projects continued increases for Ameren customers. Historically, Ameren rates have inflated about 6% per year on average. That compounds. A $170 bill today becomes $195 next year. $225 the year after. $305 by 2032 if the pattern holds.
There's some seasonal relief — Ameren's supply rate dropped to 8.4 cents/kWh for the October-May winter period. But that dip disappears every June when summer capacity pricing kicks back in. The pattern is a ratchet: summer spikes get worse, winter lows barely improve, and the annual average keeps climbing.
What's Actually in Your Control
I've been having this conversation with homeowners across Ameren territory — Belleville, Springfield, Decatur, Champaign, Edwardsville — and the reaction is always the same. Nobody likes hearing this. But they'd rather know.
A solar lease locks your rate at roughly $0.10/kWh for 15 years. Ameren's all-in rate is already over 50% higher than that, and it's going in one direction. The gap between what you'd pay on solar and what you'd pay on the grid gets wider every single year.
For homeowners who qualify, Solar for All covers the entire cost — I had a customer in Belleville whose average bill went from $245/month down to $65/month with a system that cost them nothing.
If you're in Ameren territory, your bill is going to keep doing what it's been doing. The only question is whether you're going to keep paying it or fix it. Run your numbers on our savings calculator or call me at (618) 217-2001.
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