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. But recent changes to federal policy mean you have to install your system by December 31, 2025 to claim the biggest solar incentive: the 30% federal solar tax credit. 

Installing solar panels can save you tens of thousands of dollars over time, but the upfront costs require careful consideration. Let's break down what drives the total cost and why acting soon could mean the difference between substantial savings and paying full price.

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. Remember that the federal solar tax credit will give you 30% back if you have a big enough tax bill. State and local solar rebates and incentives can cut those out-of-pocket solar costs even further.

However, President Trump recently signed legislation ending the federal solar tax credit for systems installed after December 31, 2025—nearly a decade ahead of the original 2034 schedule. This means homeowners who don’t install solar this year will miss out on around $3,003 in savings for a 3.5 kW system.

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

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: Financial incentives can drastically reduce the cost of solar, but the landscape is changing rapidly. While the federal solar tax credit only remains available through December 31, 2025, additional state and local incentive and rebate programs may also be available to you.

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:

The answer? It depends. While this guide offers a helpful starting point, determining whether a 3.5 kW solar panel system is the right fit for you requires professional input and analysis.

With the federal tax credit ending December 31, 2025, timing is important. Installation timelines typically run two to three months, and the solar industry is experiencing a significant rush of installations in the second half of 2025.

Connect with qualified solar installers in your area on the EnergySage Marketplace to design a solar panel system that's just right for your energy needs and budget—and to secure your savings before the deadline.