Which utility serves this customer?
Each Illinois utility has different net metering rules, rebate programs, and pitch angles. Selecting here loads the right calculator math and proposal template.
ComEd
ComEd / Commonwealth Edison (Exelon subsidiary) · ~4M residential customers · northern IL — Chicago metro (Cook + DuPage + Lake + Will + Kane + McHenry + Kendall counties) + Rockford / Aurora / Joliet · regulated IOU under Illinois Commerce Commission (ICC) · PJM ComEd Zone
Pre-2025 grandfather customers adding a battery + taking the $300/kWh STORAGE rebate KEEP their full-retail net metering — the storage rebate does NOT forfeit grandfather (CUB, ComEd tariff); only the SOLAR/generation rebate forfeits. Post-2025 customers (Cohort C) are on supply-only NEM by default. DG Rebate $300/kW solar + $300/kWh storage paid as a one-time check ~90 days after energization; the storage rebate requires the ComEd Rate BESH (Basic Electric Service Hourly / Hourly Pricing) switch — binding on future occupants too — and bars a Community Solar offer. PJM ComEd Zone — 2025/26 capacity-auction 833% spike flowing through supply-rate pass-through. CEJA ended full-retail NM for NEW interconnections statewide effective Jan 1, 2025 (legislated date, uniform across IOUs — NOT a per-utility peak-demand cap); pre-2025 systems grandfathered ~30 yr, and grandfather transfers with the system on sale. CRGA (eff. June 1, 2026) adds a coming ComEd VPP (short-term live ~June 2026; full SDVPP 2027).
Lead with: Grandfather PRESERVED with storage rebate (Cohort A) + Cohort C standard EDG + DG Rebate $300/kWh + PJM 833% rate hedge + Chicago resilience
Ameren Illinois
Ameren Illinois Company (Ameren Corporation subsidiary) · ~1.2M residential customers · central + southern IL — Peoria, Springfield, Decatur, Champaign-Urbana, Bloomington-Normal, East St. Louis fringe, Carbondale, Marion · regulated IOU under Illinois Commerce Commission (ICC) · MISO
Taking the $300/kWh STORAGE rebate does NOT forfeit grandfathered full-retail NM (CUB, Ameren tariff); only the SOLAR/generation rebate forfeits. So a grandfathered customer can add a battery + take the storage rebate + KEEP grandfather. B1 (take the storage rebate → enroll in one of PTR / Rider RTP / Rider PSP) vs B2 (skip the rebate → no rate-plan switch) is therefore NO LONGER a grandfather-vs-rebate tradeoff — both keep full-retail NM; it's just take-the-rebate-and-switch vs skip-it. (Ameren forfeits grandfather only on a >100% nameplate GENERATION increase — a battery never triggers that.) Cohort C (post-2025) has no grandfather to lose. DG Rebate $300/kW solar + $300/kWh storage, paid as a one-time check ~90 days after energization; the storage rebate's rate-plan choice is binding on future occupants. MISO — PJM 833% framing does NOT apply here.
Lead with: Grandfather kept with storage rebate (no tradeoff) + DG Rebate $300/kWh + PTR/RTP/PSP rate choice + MISO rate hedge + central/southern IL resilience