How much does a 3.5 kW solar panel system cost in 2025?

If you've been considering solar, you're probably curious about costs—and maybe a little envious of neighbors who've already made the switch and are enjoying lower electric bills. A 3.5 kilowatt (kW) solar panel system can help power your home while significantly reducing monthly utility costs.

In 2025, a 3.5 kW solar panel system costs around $10,010 before incentives, based on real installation data from across the country. But your actual price will depend on factors like your roof’s complexity, local labor costs, the equipment you choose, and what incentives are available in your area. 

Let's break down those costs so you can determine whether a 3.5 kW system is the right size for your home.

On average, a 3.5 kW solar panel system costs $10,010, according to real-world quotes on the EnergySage Marketplace from 2025 data. However, your price may differ—solar costs can vary significantly from state to state.

The table below should give you an idea of what you can expect to pay for a 3.5 kW solar panel system in your state. Depending on where you live, state and local solar rebates and incentives may help cut these costs.

How much does a 3.5 kW solar system cost in my state?

What affects the cost of a 3.5 kW solar panel system?

In the end, your total bill depends on a bunch of different factors. Here are a few to keep in mind: 

• Brand and quality of equipment: High-efficiency solar panels generally cost more than their less-efficient counterparts. Likewise, some premium brands can get away with charging more than others.

• Special accommodations: Some properties are better suited for solar than others. Your system will probably cost more if you have a particularly complicated roof.

• Permits and inspections: To install a solar panel system at your home, you'll need certain permits, which sometimes come at a cost.

• Labor costs: Installing solar is a specialized skill, so labor drives construction costs.

• Supply chain constraints & market fluctuations: Like any industry, the solar market has faced its fair share of ups and downs. Most recently, we experienced an ebb in the early 2020s, with solar prices rising for the first time in years. Fortunately, the cost of solar is at an all-time low as of 2025, though newly introduced tariffs could change that in the near future.

• Incentives: State and local incentive and rebate programs may be available to you and can significantly reduce your upfront costs.

Cost isn't the only thing that varies from state to state: You'll also see fluctuations in electricity production. The average 3.5 kW solar panel system in almost-always-sunny Phoenix, Arizona produces about 35% more electricity than that same system installed in seasonally-sunny Boston, Massachusetts. (That said, you don’t have to live in Arizona for solar to be a good option for your home. Solar is a smart investment wherever electricity rates are high). 

With the help of PV Watts, we estimated the solar energy production of a 3.5 kW solar panel system in cities across the country: 

Solar electricity output of a 3.5 kW solar panel system in U.S. cities

We generally don’t recommend a do-it-yourself solar installation. Installing solar panels involves skilled work across multiple trades. Attempting to install a system yourself increases the likelihood of costly mistakes, potential safety and electrical hazards, and even damage to your home, especially if you intend to install your system on a roof. That said, if you’ve made up your mind about DIYing your solar panel system, a small-scale project like a 3.5 kW system might be doable.

DIY solar panel systems can be practical for powering small, off-grid setups like cabins, RVs, boats, or tiny homes. A few things to consider as you explore do-it-yourself solar:

A 3.5 kW system produces roughly 5,082 kWh annually on average—enough to power a tiny home. 

The specifics matter: Your actual electricity consumption, your roof's orientation and shading, your local climate, and available incentives in your area. That's why working with a qualified installer to assess your home and design a system tailored to your situation is the best way to ensure solar delivers the savings you're expecting.