Northern Illinois · ComEd · ten months of real data

Is Rooftop Solar Still Worth It in Chicago?

In June 2025 I signed up for a 9.9 kW solar system on my house in Chicago. It switched on December 23, 2025. I’m a ComEd customer, I charge an electric car at night, and I kept every bill and every hour of production data. Ten months in, I sat down with all of it to answer three questions: did the system do what the installer promised, which ComEd rate gets the most out of it, and would I still do it today, now that the 30% federal tax credit is gone?

This post is what I found, with my real numbers. It’s written for friends and anyone else in ComEd territory who is thinking about solar now. The rules are Illinois-specific, but most of the reasoning carries over elsewhere.

Written Oct 2026Data: Dec 23, 2025 – Oct 26, 2026Not financial advice; estimates, not guarantees

The short answer

With the 30% federal credit (what I got in 2025), solar was a good investment: roughly a 10–14% yearly return, tax-free, paying for itself in 8–10 years.
Without it (anyone installing from 2026 on), the same system at the same price returns roughly 3–9% a year and takes 12–17 years to pay back. That’s a maybe, not a yes. It mostly comes down to the price you pay per watt.
The rate plan matters almost as much as the panels. ComEd’s Time-of-Day (TOD) rate makes my solar worth about 50% more than the Hourly rate I started on.
Expect the installer’s numbers to be optimistic. My system produced ~90% of its estimate, and my first-year savings on the rate I started with were ~60% of what the proposal showed.
You don’t need an EV for this to work. Our car charges at night, so it barely uses the solar. With its charging taken out of my data, TOD’s advantage gets slightly bigger.
Batteries don’t pay for themselves yet. Buy one for backup power, not for savings.

A few terms first

kWh: A kilowatt-hour, the unit on your bill. A typical Chicago house uses 600–1,200 a month; mine is higher because of the car.
Net metering: When your panels make more than the house is using, the extra flows out to the grid and ComEd credits you for it.
The 2025 rule change: Systems connected on or after Jan 1, 2025 are credited only for the supply part of the price, not delivery, taxes or fees. An exported kWh is worth roughly a third of what a kWh you avoid buying is worth. This is the single biggest thing to understand.
Supply vs delivery: Your ComEd bill has two halves. Supply is the electricity itself. Delivery is the wires. You can pick how supply is priced; delivery is ComEd’s regardless.
ComEd supply options: Fixed: one price all day (~10.4¢ summer, ~8.7¢ rest of year). Hourly: follows the wholesale market every hour, plus a monthly capacity charge. Time-of-Day (TOD): four fixed price blocks each day.
Delivery Time-of-Day: A delivery option with cheap overnight and expensive 1–7 pm prices. It pairs with any supply plan and is great for EV owners. I had it from the start.
Incentives (2025): Illinois Shines, a state program that pays upfront for your system’s renewable energy credits (about 36% of my price). ComEd DG rebate, $300 per kW. Federal tax credit, 30%, ended for systems installed after Dec 31, 2025.

My system and what it actually did

22 panels, 9.90 kW DC, Enphase microinverters, on the east and west sides of a low-pitched ranch roof in Chicago (12 panels face east, 10 face west). Here is the installer’s proposal next to the first ten months, scaled to a full year where needed.

Our household We have one EV. My wife drives it about 40 miles a day to work, and in ski season I add about four 100-mile days a month driving our kid to ski-racing practice. We charge at home overnight. From the hourly data, the car is roughly 5,500 kWh a year, about 37% of everything the house uses. A normal night is 10–15 kWh, and a night after a long winter drive is 45–50 kWh. That’s why our usage runs 14% above what the installer assumed.

	Proposal	Actual
Production, first year	11,064 kWh	~10,000 kWh	~90%
Household usage per year	12,950 kWh	~14,700 kWh	+14% (EV)
Value of each kWh produced	17.19¢	9.7¢ on Hourly	much lower
Bill savings per year	$1,548	~$950 Hourly / ~$1,400 TOD	close on TOD

Production came in about 10% low. A couple of weeks of snow cover in late January cost ~2%, and one sunny day the system was simply off. Even without those, it would have been ~92–93% of the estimate. The installer guarantees 90% over 25 years, so my first year is right at that line.

Hot days cost something too. In the hottest clear hours of summer, the panels made about 15% less per unit of sunlight than on cold, clear winter days. That’s normal: solar panels lose efficiency as they heat up, and a good production estimate already accounts for it.

Where my solar went

Used at home 37%Sent to the grid 63%

Savings came in low because most of my solar is exported. The 37% used in the house is worth about 16¢ per kWh, because I avoid buying that power at full price, including delivery and taxes. The 63% sent to the grid earned only about 6¢ per kWh on the Hourly rate, because of the 2025 supply-only rule. The proposal valued every kWh at 17.19¢. That one assumption explains most of the gap.

So far: $541 saved from solar used at home, plus $349 in export credits, for $889 in ten months.

Hourly vs Time-of-Day: why the rate plan matters

I started on Hourly supply. It looked smart: real-time prices are often 2–5¢ at night, perfect for charging a car. But Hourly has two problems for a solar house. It adds a fixed capacity charge (mine was ~$24.50 a month, set from my usage before the panels existed), and it credits exports at the real-time price, which is low in the middle of a sunny day.

TOD, which ComEd rolled out in 2026, uses four fixed blocks every day of the year:

Overnight 9p–6a2.829 / 3.394¢Charge the car here.

Morning 6a–1p3.778 / 4.768¢Lots of solar, low credit.

Mid-Day Peak 1p–7p16.594 / 14.699¢Solar exports earn the most.

Evening 7p–9p5.793 / 6.009¢Sun’s down.

TOD supply prices per kWh, summer (Jun–Sep) / rest of year, 2026, from the Citizens Utility Board. They reset every June.

Which way your panels face matters on TOD. East-facing panels produce mostly in the morning block, which pays the least. West-facing panels keep producing into the 1–7 pm peak, which pays the most. On my east/west roof, 56% of production lands in the morning block and 44% in the peak block. A kWh exported in the peak block earns roughly 2.5 to 4 times one exported in the morning block, so on TOD west-facing panels earn noticeably more per kWh than east-facing ones.

For a solar house that’s a good deal. There’s no capacity charge, and solar sent out between 1 and 7 pm earns ~15–18¢ instead of a few cents. The cost is that overnight car charging runs about 0.75¢ per kWh more than the Hourly average, around $5 a month for me. Charging is still ~11¢ per kWh all-in on any plan, because delivery, fees and taxes are most of the price.

I re-ran all ten months of my bills as if I’d been on TOD the whole time, using the real hourly data. TOD came out ahead in every scenario I tested. How far ahead depends on one rule ComEd doesn’t clearly publish, covered next. I’ve since switched.

Who can get TOD with solar Systems connected before 2025 on the old “full retail” net metering can’t use TOD without giving that up. Systems connected since Jan 1, 2025 that received ComEd’s DG rebate are the ones the Citizens Utility Board says can benefit. Confirm with ComEd before enrolling.

The open question: how does ComEd credit solar on TOD?

This is the one piece I couldn’t pin down from ComEd itself. Its net-metering FAQ covers fixed-price and Hourly customers but says nothing about TOD. The question: when your panels send power to the grid during a TOD block, what exactly do you get? I found four plausible answers and ran my numbers under each.

To make them concrete, take one month in which, during the peak block, the house sends out 300 kWh and draws 60 kWh, so 240 kWh net out. Overnight the car and house draw 900 kWh.

A. Money at the block’s priceMost likely

Every kWh you send out earns that block’s supply price, as dollars on your bill. Peak exports earn ~14.7–16.6¢, morning exports ~3.8–4.8¢. The dollars pay for anything on the bill, including overnight charging. Hourly already works this way, just with hourly prices instead of block prices.

Example: 240 kWh × 14.699¢ = $35.28 credit, minus 900 kWh × 3.394¢ = $30.55. Supply bill: −$4.73.
My ten months: supply cost −$112 vs $346 on Hourly.

B. Money at a flat pricePossible

Exports earn the standard fixed supply price (~10.4¢ summer, ~8.7¢ rest of year) no matter when you export. Fixed-price customers get this option today.

Example: 240 kWh × 8.677¢ = $20.82 credit. Supply bill: +$9.73.
My ten months: −$147 (slightly better than A for me, because I also export a lot in the morning).

C. Money at the real-time priceUnlikely

Exports earn the wholesale market price of that hour, as on Hourly: usually 2–6¢, sometimes much more on hot afternoons. You’d lose most of TOD’s advantage but still skip the capacity charge.

Example: 240 kWh × ~4¢ ≈ $9.60 credit. Supply bill: ~+$21.
My ten months: $192.

D. kWh netting inside each blockWorst case

Exports only cancel out power you draw in the same block. Extra kWh are banked for that block in later months and never turn into money. A solar house sends out power in the morning and afternoon but draws it overnight, so the bank piles up and never pays for car charging.

Example: 240 kWh banked for future peak hours, $0 now; you pay the full $30.55 overnight. Supply bill: +$30.55.
My ten months: $296, with ~4,700 kWh stuck in the bank.

The example uses non-summer supply prices only. Ten-month results compare supply cost on TOD with my actual Hourly bills; delivery is identical either way.

Why I think it’s A

The installer’s rate guide says so in plain terms. Certasun, which installs in the Chicago area, writes that on TOD “each kWh you send to the grid earns the supply part of that period’s price”, and lists a credit for each block (about 4.7–18.5¢ including small add-on charges).
A description of ComEd’s TOD tariff found during research says customers connected since 2025 get credit “for the net amount of kWh provided to the grid at the supply rate applicable to that period.” That is A, applied block by block. I couldn’t open the tariff document itself to confirm it.
It matches how ComEd already credits solar. Hourly customers are paid in dollars at the price of the hour, and fixed-price customers can choose dollars. Netting only within a block, as in D, would be an odd exception for a rate that ComEd and consumer groups pitch to solar owners.

Under A, B, or C, TOD wins clearly. Under D it still wins for now, barely, because the capacity charge goes away. But once a solar home’s Hourly capacity charge drops (it’s reset each June from usage during the grid’s peak hours, and mine should fall from ~$24.50 to ~$5 a month in June 2027), Hourly would come out ahead under C or D.

How to find out for yourself Look at your first TOD bill. A dollar line such as “Net Metering Credit … −$XX.XX” means A (or B). A kWh balance carried forward by time block means D. Leaving TOD carries no penalty, but switching takes up to three billing cycles, and once you leave you can’t rejoin for 12 months.

What if you don’t have an EV?

Our situation is specific, so I checked how much the car changes the answers.

The EV doesn’t make solar pay more. It charges between 9 pm and 6 am, when the panels make nothing, so it uses almost none of our solar. Our solar savings would be about the same without it.
Solar home, no EV: TOD looks even better. I removed the car’s estimated charging from ten months of hourly data and re-ran the comparison. TOD beat Hourly by about $505 instead of $459 (and by ~$311 instead of ~$265 once a solar home’s capacity charge drops). Overnight charging is the one thing TOD prices slightly higher than the Hourly average, so less of it helps TOD.
Without an EV, size the system carefully. A house that uses less power exports a bigger share of its solar, and exports earn only the supply price. A system much bigger than what you use during the day earns noticeably less per panel. Ask the installer what share of production they expect you to use at home.
Heavy afternoon use is TOD’s weak spot. Power bought between 1 and 7 pm costs about 31–33¢ per kWh all-in on TOD. With solar, the panels cover most of those hours. Without solar, a house running central air all afternoon, or someone working from home with a lot of equipment, can pay more on TOD than on a flat rate.

No solar at all?

The same rate choice applies, minus the export credits. Roughly:

TOD suits households that can keep heavy use out of 1–7 pm: EV charging overnight, laundry and dishwasher in the morning or evening.
Hourly (with Delivery TOD) suits people comfortable with prices that change every hour, especially with an EV, since real-time overnight prices are often very low. Its capacity charge is based on how much you use during the grid’s peak summer afternoon hours, so heavy afternoon air conditioning makes it more expensive.
Fixed price is the safe choice if most of your use is in the afternoon and can’t move.

The only way to know for sure is to price your own usage hour by hour; the checklist below explains how to get that data.

Would I do it again without the federal credit?

Same system, same $34,190 price ($3.45 per watt), same savings on TOD (~$1,400 in the first year, assuming case A), panels losing 0.25% output a year. The only difference is the missing 30% federal credit. My installer also expected the Illinois Shines and ComEd payments to count as taxable income; I did pay tax on them, so that’s included in the first row of each case.

Your cost after incentives	Prices flat	+2%/yr	+4%/yr	Payback
2025, with federal credit: $12,776 incl. tax on incentives	9.7%	11.6%	13.6%	8–10 yr
2025, if incentives weren’t taxed: $8,660	15.5%	17.5%	19.4%	6–7 yr
2026+, no federal credit: $23,033 incl. tax on incentives	3.3%	5.2%	7.0%	14–17 yr
2026+, if incentives aren’t taxed: $18,917	5.2%	7.1%	9.0%	12–14 yr

Percentages are the yearly return over 25 years (IRR), tax-free because it comes as lower bills. Columns are how fast electricity prices rise; the proposal assumed 4%. No value is counted for the system after 25 years, or for any increase in home value.

For comparison, an S&P 500 index fund has averaged about 10% a year over the long run, roughly 8.5–9% after taxes in a regular account, and you can sell it any time. Without the federal credit, solar at my price is roughly a wash with the stock market, or worse. The good news is that the price per watt moves the answer a lot:

Installed price	System price	Return, prices flat	Return, +3%/yr
$3.45/W (what I paid)	$34,155	3.3%	6.1%
$3.00/W	$29,700	5.4%	8.2%
$2.50/W	$24,750	8.9%	11.8%

2026+, no federal credit, incentives taxed, same incentives and savings as my system.

Over the first ten months, the money I put in would actually have done better in an S&P 500 fund (~$1,500 gain vs $889 saved), but that was an unusually strong market year, and solar’s advantage builds slowly over decades.

What about a battery?

TOD makes a battery more useful than it is on Hourly. It can store cheap morning solar (worth ~6¢ exported) and use it during the 1–7 pm peak (worth 17–33¢). I simulated a 13.5 kWh battery on my real hourly data: about $220–350 a year in savings. It would cost roughly $14–16k installed, minus a $300/kWh ComEd rebate (~$4,050), with no federal credit, so 30+ years to pay back. Most batteries are warrantied for 10–15. Buy one if you want backup power during outages; don’t buy one to save money. The ComEd rebate also requires staying on Hourly or TOD for the life of the battery.

If you’re shopping for solar now

Get your last 12 months of usage, by the hour if you can. In my ComEd account, the “Green Button” download only gave monthly totals, which isn’t enough to compare rates. ComEd’s smart meters record usage through the day (that’s how Hourly and TOD billing work), so call ComEd at 1-800-334-7661 and ask for your hourly or interval usage data. Then download ComEd’s past hourly prices from hourlypricing.comed.com and match them against your usage, hour by hour. Power used while the sun is up is worth ~16¢; power sent to the grid is worth 3–18¢ depending on your rate. The more you use during the day, the better solar pays.
If you go solar, get consumption monitoring. My Enphase system measures both what the panels make and what the house uses, every hour. That’s what made this whole analysis possible. Without it, ComEd only sees what goes in and out at the meter, not what you use directly from the panels.
Ask for savings modeled with supply-only export credit. If a proposal values every kWh at one retail price, like my 17.19¢, it’s overstating the savings.
Shave ~10% off the production estimate unless the installer shows you a shade report and explains how snow is modeled. Ask for the month-by-month production estimate so you can check it later.
Push hard on price per watt. Without the federal credit, each $0.50 per watt is worth 2–3 points of yearly return. Get at least three quotes.
Budget for taxes on incentives if your tax preparer agrees they’re taxable. For me that was roughly 27% of the Illinois Shines and ComEd amounts. Check the current Illinois Shines and ComEd rebate amounts, since they change.
Plan to use TOD if your system qualifies, especially if you charge an EV. Charge overnight, and run the laundry and dishwasher outside 1–7 pm. If you’re choosing which roof faces get panels, favor west over east.
Read the production guarantee’s fine print. Mine promises 90% of the estimate over 25 years and pays 16¢ per missing kWh, but the proposal doesn’t say whether it’s checked yearly or only at the end, or what’s excluded.
Ask about leases and power-purchase agreements (PPAs). Some sources say a commercial federal credit (Section 48E) still applies when a company owns the system on your roof, and part of that can show up in your price. I haven’t verified this; compare total 25-year cost, and read the contract terms around selling your house.
Skip the battery unless you want backup power.

What I’m watching next

My first TOD bills, to confirm export credits come as dollars (case A).
Production every December 23 against the installer’s 90% guarantee line (~9,958 kWh for year one).
A few unexplained dips on sunny afternoons, which may be the inverters shutting off briefly when grid voltage runs high. I’m checking the Enphase event log, and I’ll ask ComEd for a voltage check if it shows voltage events.
TOD vs Hourly, every year. TOD prices and the Hourly capacity charge both reset each June, so the best plan can change.