January is a good month to answer one of the most common questions we hear: “How many solar panels would my house need?”
Here’s why the timing works. With 2025 behind us, you now have a full year of electric bills, and those bills hold most of the answer. In this guide, we’ll walk through the same basic math we use as a starting point, with real examples for homes in Ohio, Kentucky and Indiana.
Step 1: Find Your Yearly Electricity Use
Solar systems are sized around how much electricity you use in a year, measured in kilowatt-hours (kWh).
Add up the kWh on your last 12 bills. Many utilities also show a 12-month usage history right on the bill or in your online account. Using a full year matters, because your usage swings between summer air conditioning and winter heating.
For reference, here’s what average homes used per month in 2024, according to the U.S. Energy Information Administration:
- Ohio: about 846 kWh per month (roughly 10,150 kWh per year)
- Indiana: about 901 kWh per month (roughly 10,800 kWh per year)
- Kentucky: about 1,047 kWh per month (roughly 12,560 kWh per year)
Your number may be higher or lower, especially if you heat with electricity, have a pool or drive an electric vehicle.
Step 2: Estimate How Much Each Kilowatt of Solar Produces Here
A 1-kilowatt (kW) solar system in our region produces roughly 1,100 to 1,250 kWh per year, depending on roof direction, tilt and shading. That’s less than in Arizona, but plenty to make solar work, as thousands of homeowners across the region already know.
For our examples, we’ll use 1,150 kWh per kW per year as a middle-of-the-road figure.
Step 3: Do the Math
Divide your yearly use by that production figure to estimate your system size:
Yearly kWh ÷ 1,150 = system size in kW
Then convert that to panels. Most home solar panels today are rated around 400 to 460 watts. Using 400-watt panels:
System size in kW ÷ 0.4 = number of panels
Real Examples for Average Homes
| Average home in… | Yearly use | Estimated system size | About how many 400 W panels |
|---|---|---|---|
| Ohio | ~10,150 kWh | ~8.8 kW | ~22 panels |
| Indiana | ~10,800 kWh | ~9.4 kW | ~24 panels |
| Kentucky | ~12,560 kWh | ~10.9 kW | ~27–28 panels |
These estimates aim to cover about 100% of a year’s electricity use. Many homeowners choose a smaller system that covers part of their use, based on budget, roof space or how their utility credits solar.
What Changes the Number
The quick math gets you in the ballpark. A real design accounts for things a calculator can’t see:
- Roof direction and pitch. South-facing roofs produce the most. East- and west-facing roofs still work well but may need a few more panels.
- Shade. Trees, chimneys and neighboring buildings can cut production.
- Roof space. Your roof may physically fit fewer panels than the math suggests, which is where higher-wattage panels help.
- Future plans. An electric vehicle, heat pump, hot tub or home addition can raise your usage, so it’s worth planning ahead.
- Utility rules. Utilities may have their own rules on system size and how excess solar is credited, which can shape the best size for your home.
- Battery storage. If you’re adding a home battery for backup power, that can affect how the whole system is designed.
Why a Real Site Visit Still Matters
Online estimates are a great starting point, but they can be off by a lot if they don’t account for your roof and shade. (Our Wealth Warrior Wanda wrote about this years ago in How Accurate Are Those Online Tools?)
When we design a system, we look at your actual usage history, your roof’s layout and shading, and your goals, whether that’s lowering your bills, adding backup power, or both.
Get Your Number
Have your 2025 bills handy? That’s the perfect starting point. Request your free quote and we’ll give you a system size based on your home, not an average.
Want to learn more first? Read why winter is a smart time to start the solar process, see how long solar panels last, explore solar for your home, or review solar financing options.
Icon Solar has helped homeowners across Ohio, Kentucky and Indiana go solar since 2009. Call us at (866) 396-4266.
Frequently Asked Questions
How many solar panels does it take to power a house?
It depends on your electricity use. An average Ohio home using about 10,150 kWh a year would need roughly 22 400-watt panels to cover its full use. Average homes in Indiana and Kentucky use more and may need about 24 to 28 panels.
How do I calculate how many solar panels I need?
Add up a year of electricity use in kWh, divide by about 1,150 (a typical yearly production per kW of solar in Ohio, Kentucky and Indiana) to get system size in kW, then divide by your panel wattage in kW (0.4 for a 400-watt panel).
How much electricity does a 1 kW solar system produce in Ohio?
Roughly 1,100 to 1,250 kWh per year, depending on roof direction, tilt and shading.
Do I need enough panels to cover 100% of my electricity use?
No. Many homeowners install a system that covers part of their use based on budget, roof space and how their utility credits solar. A solar professional can help find the right balance.
What size are most home solar panels?
Most home solar panels quoted today are rated around 400 to 460 watts.
