15 Best Solar Companies in Diamond Bar, CA (2025 Reviews)
We analyzed over 1500 solar companies in the nation,
and have selected the top 15 in Diamond Bar based on:
Customer review scores
Service area for Diamond Bar, CA
Company policies and services offered
Accreditations and certifications
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Average Diamond Bar homeowner saves $2,108/year with solar panels
Why you can trust EcoWatch
Best Solar Companies in Diamond Bar
When choosing between the best solar companies, Diamond Bar homeowners have more options to choose from than ever before, which can be too much to get a handle on, but we’re here to make switching to solar energy that much easier. Because Diamond Bar has a very high capacity for solar energy generation, switching to solar is financially rewarding for many homeowners.
If you’re thinking about going solar, the first step you should take is to find the best solar companies in Diamond Bar and compare quotes. The great news is we took the time and put together a list of the best solar companies so you don’t have to.Continue reading to see our picks for the top solar companies in the city, or get connected with a certified solar company in your area right away by clicking the button below.
Best Regional Coverage
Momentum Solar
- Great warranty coverage
- Representatives are experts on local policies
- Concierge service ensures steady communication
- Slightly limited service offerings
Best for Leasing
Sunrun
- Expansive service area
- Many financing options
- Some reported issues with customer service
- Some reported issues with door-to-door sales
EcoWatch Rankings for Solar Companies in Diamond Bar

SunPower by Sea Bright Solar
Clear Pricing Policy
Reliable Customer Support
Free Quotes
Limited information available on website
Services Offered
Financing Assistance
Battery Storage
Panel Installation
Consultation


SunPower by Sun Solar-OC
Reliable Customer Support
Limited information available on website
Services Offered
Consultation
Battery Storage
Panel Installation
Cleaning and Maintenance



SolarRepair
Informative Resources
Clear Pricing Policy
Reliable Customer Support
Free Quotes
Prompt Service Delivery
Limited information available on website
Services Offered
Panel Installation
Cleaning and Maintenance
Skilled Repairs
Battery Storage
Financing Assistance
Solar Panel Upgrades

Altadena Energy & Solar
Reliable Customer Support
Informative Resources
Clear Pricing Policy
Free Quotes
Limited information available on website
Services Offered
Panel Installation
Battery Storage
Permit Assistance

SunSolar U.S.
Clear Pricing Policy
Informative Resources
Free Quotes
Reliable Customer Support
Prompt Service Delivery
Limited information available on website
Services Offered
Battery Storage
Panel Installation
Financing Assistance
Consultation
Solar Carports
Permit Assistance

REPOWER OC
Prompt Service Delivery
Clear Pricing Policy
Free Quotes
Informative Resources
Reliable Customer Support
Limited information available on website
Services Offered
Financing Assistance
Panel Installation



Solar Source
Family-Operated Business
Reliable Customer Support
Informative Resources
Clear Pricing Policy
Free Quotes
Limited information available on website
Services Offered
Panel Installation
Permit Assistance
Financing Assistance


Powerfull Solar, Inc
Informative Resources
Prompt Service Delivery
Reliable Customer Support
Free Quotes
Limited information available on website
Services Offered
Cleaning and Maintenance
Solar Carports
Consultation
Panel Installation
Permit Assistance
Financing Assistance

ProSolar California
Free Quotes
Informative Resources
Reliable Customer Support
Limited information available on website
Services Offered
Financing Assistance
Tesla Powerwall
Battery Storage
Panel Installation
Methodology: How We Ranked the Best Solar Companies in Diamond Bar
EcoWatch's solar experts analyzed each solar company in Diamond Bar based on criteria such as its reputation in the industry, customer reviews, services, warranty coverage and financing. Using this solar methodology, we used the data we collected to rate and rank each company and narrow down our picks for the best solar companies in Diamond Bar
Below are some the criteria we examined specifically for California solar companies
- Brand reputation and certifications (20%): We take each company's Better Business Bureau (BBB) score into consideration, as well as how long the installer has been in business (at least 5 years is required, 10 preferred) and what type of solar certifications it holds.
- Customer reviews (20%): Trust is a top priority at EcoWatch, so we take customer experience under close consideration. We scour different review sites and customer testimonials when ranking our top solar companies, checking sites such as Trustpilot and Google Reviews. We also consider any potential complaints or lawsuits filed against these companies and award or remove points accordingly.
- Warranty (20%): A company earns a perfect score in this category if it offers 25-year warranties that cover performance, product and workmanship. The industry standard that we measure companies against is 25-year product and performance warranties, along with a 10-year workmanship warranty. We also look closely into the track record of the post-installation support each company provides in terms of honoring its contracts
- Solar services (10%): All of the companies we review install solar panels, but we award companies higher points if they offer additional services for customers, like battery installation, energy-efficiency audits, and EV chargers.
- Pricing and financing (10%): It's hard to get exact quotes for solar projects, but we use marketplace research to determine how each company prices its equipment and installation services. Additionally, companies that offer more help for panel financing — like in-house loans, leases, or PPAs — score higher than those that don't.
- Availability (10%): The bigger the service area, the higher the company will score.
- Transparency and accessibility (5%): Solar installers that offer free consultations and easy contact methods score higher in this category.
- Environmental, social and corporate governance factors (5%): A company earns a perfect score in this category if it offers public data disclosure, addresses end-of-life (EOL) products or processes, and demonstrates a commitment to uplifting the communities that it serves.
The Cost and Benefits of Solar in Diamond Bar
The cost of installing a solar panel system has gone down significantly in the past several years, but it’s still a significant investment for most homeowners.The cost of solar and the savings it generates vary depending on some important factors such as:
- The kind of solar panels you’re thinking of getting: Higher-efficiency panels have higher prices, so that will shape your budget for your solar project.
- Incentives: Along with the federal Solar Investment Tax Credit (ITC), which lets you deduct 0 of your overall installation cost, your state or local government may offer additional tax exemptions, credits or rebates that will help you save even more. Excluding incentives, you can save an average of $25,000 over the first 20 years with your solar system, too.
- The amount of sunlight your roof gets: Because of Diamond Bar’s very high amount of average daily sunlight, you should be able to save a lot on your electricity bills.
- Energy consumption: Installing solar panels may be too steep of an investment for homes that don’t use too much energy each month.
Solar is a worthwhile investment for most homeowners. You can produce your own electricity instead of paying for it from a utility company and make use of solar tax credits and rebates, all while helping protect the planet.
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Solar Incentives in Diamond Bar
Although installing solar panels is typically a big investment, it can save you a substantial amount of money over time because of lower utility bills and government incentives.Regardless of what state you live in, you can take advantage of the federal Solar Investment Tax Credit (ITC), which will allow you to claim 0 of how much you paid for your solar installation when you file taxes, reducing the amount of taxes you owe that year. In addition, there may be some local incentives you can benefit from too. In our article on solar incentives, you can read about the incentives you qualify for near you.
Environmental Impact of Switching to Solar in Diamond Bar
One of the best reasons to use solar power is to decrease your dependence on nonrenewable energy sources like burning fossil fuels, which are damaging for the environment.But – how much exactly can you help the environment by making the switch to solar? A key thing to keep in mind is your overall carbon footprint. For example, if you have a long commute, your footprint may be greater, so adopting solar power for your home can help offset that.In fact, if you install solar panels, you could reduce your carbon dioxide emissions by about 50 pounds each year. If you care about the environment, you’ll likely find that there are many benefits of adopting solar power other than just saving money on bills. You can also help protect the environment, which some would argue is more valuable.
Best Regional Coverage
Momentum Solar
- Great warranty coverage
- Representatives are experts on local policies
- Concierge service ensures steady communication
- Slightly limited service offerings
Best for Leasing
Sunrun
- Expansive service area
- Many financing options
- Some reported issues with customer service
- Some reported issues with door-to-door sales
EcoWatch's Diamond Bar, CA Solar Company Rankings FAQs
What is the best solar company in Diamond Bar?
In Diamond Bar, SunPower by Sea Bright Solar is the top local solar company. Our team of experts rates it 4.40 stars, so it's a solid choice if you're planning to add solar panels to your roof.
What is the negative environmental impact of solar panels?
Manufacturing solar panels requires chemicals and produces toxic waste that can be bad for the environment, which is the main downside of solar panels.
How long does it take for solar to pay for itself?
Solar panels usually pay for themselves in about 9.2 years, but your solar payback period will vary based on your utility costs. The higher your typical energy bill, the faster your solar panel system will pay for itself.
When should I install solar panels?
You can install solar panels whenever it's convenient for you, but consider doing so in the winter when the demand is less. With fewer homeowners going solar, you could potentially see faster installation times and more savings.
Our goal is to reach as many people as we can with sensible solutions like solar energy. Our team of full-time local researchers collects solar price and installation data for every city in America then compiles it to create these digestible city guides. If you want to read our solar expert’s opinion on the top solar companies featured here, follow this link.
Company research was conducted by Melissa Smith and Karsten Neumeister. Local data analysis was conducted by James Savino. See something we missed or could do better? Email the editor.