Williamson County, IL solar installation & market data
Updated October 1, 2026 By The SolarDNA Data Team
Williamson County has 824 solar installations across 11 zip codes, installations up 36.8% over the trailing twelve months, and an installs-weighted Market Score of 48.
Active installations
824
Zip markets
11
Median cost
—
12-mo growth
▲ 36.8%
Installers active
44
County Market Score
Great · installs-weighted across 11 zips
Best zip in Williamson County scores higher than 97% of U.S. zip markets.
Versus Illinois
How Williamson County compares with the state
Installed cost
—
state median $6.56/W
Market score
48 vs 43
Illinois scores 43
Share of state installs
0.73%
of 112.7K tracked statewide
Battery attach
0.0%
state 0.0%
Statewide momentum
▲ 23.1%
residential solar added in Illinois, 12 months through Jul 2026
Statewide market
136.9K systems
4.0% of homes · utility-reported through Jul 2026
Next-12-month outlook: 247–335 installs (midpoint 291)
Trailing-12-month installs carried forward at half the observed growth rate (capped at ±30%), with a ±15% band. Not a forecast of permits or policy.
Growth & pricing
Williamson County by year
253 installs in the trailing twelve months vs 185 before
Installations by year
Median installed cost, $/W DC by year
Installer comp set
Who installs in Williamson County
Summed across every zip in the county
| # | Installer | Installs | 12-mo | Zips | $/W |
|---|---|---|---|---|---|
| 1 | LGCY POWER | 73 | 52 | 8 | — |
| 2 | ADVANCED ENERGY SOLUTIONS GROUP | 57 | 34 | 7 | — |
| 3 | RESIDENTIAL SERVICE PROVIDERS | 49 | 22 | 9 | — |
| 4 | SOLARSHIPS INSTALLATION SERVICES | 40 | 38 | 7 | — |
| 5 | CR SOLAR | 24 | 19 | 3 | — |
| 6 | FREEDOM FOREVER | 24 | 22 | 6 | — |
| 7 | CORVUS PRO SOLAR LLP | 8 | 5 | 4 | — |
| 8 | D&D ELECTRIC | 8 | 3 | 6 | — |
| 9 | SUN SOLAR | 8 | 5 | 4 | — |
| 10 | ABSOLUTE CLIMATE D B A C H ELECTRIC | 8 | 1 | 3 | — |
| 11 | GOODPWR | 6 | 6 | 5 | — |
| 12 | TRON SOLAR | 5 | 4 | 4 | — |
| 13 | ABSOLUTE CLIMATE | 4 | 1 | 1 | — |
| 14 | REVOLUTION ENERGY SYSTEMS | 4 | 4 | 3 | — |
| 15 | OFF GRID BLUE SKY SMART SOLUTIONS | 3 | 0 | 2 | — |
| 16 | OFF GRID ENERGY SOLUTIONS | 3 | 3 | 2 | — |
| 17 | WOLFPACK ELECTRIC | 3 | 3 | 2 | — |
| 18 | POWUR PBC | 3 | 3 | 2 | — |
| 19 | AVEYO OFF GRID ENERGY SOLUTIONS | 3 | 3 | 3 | — |
| 20 | TITAN SOLAR POWER | 3 | 0 | 2 | — |
| 21 | FOWLER HEATING & COOLING | 2 | 2 | 1 | — |
| 22 | CONTEMPORARY CONTRACTING | 2 | 1 | 1 | — |
| 23 | A& I BUILDERS | 2 | 2 | 2 | — |
| 24 | ADVANCED RENEWABLE CONCEPTS | 2 | 0 | 2 | — |
| 25 | MISSOURI SUN SOLAR | 2 | 0 | 1 | — |