Know the most important things to look at when comparing multiple solar quotes.
There are a lot of important steps along the journey to getting solar panels installed. You should learn how solar panels work, how long they last, how they can save you money, and whether you qualify for solar incentives.
After you’ve done your homework and decided that solar panels are right for you, it’s time to get solar quotes from multiple companies and compare them to choose the best.
Comparing solar quotes isn’t as simple as finding the company that offers the lowest price or the best equipment. Let’s explore the important factors to consider and outline how to compare between companies.
Key takeaways
- A first step toward finding the right solar installation company is to read customer reviews online.
- Once you’ve received quotes from solar installers, compare their offers based on system size, cost per watt, estimated energy production, equipment used, warranties, and financing options.
- A great solar installer will be able to explain everything in their quote, answer any questions you have, and give you a full picture of project timelines, from contract signing to final grid interconnection.
Reviews of the companies
As the industry-leading website for unbiased consumer reviews of solar companies, it may be no surprise that we recommend this as a first step to evaluating a solar company. Nobody knows a company better than its former customers, and we have gathered tens of thousands of reviews of solar companies on our site.
Here’s SolarReviews founder and CEO Andy Sendy with some more information about what to look for in a solar company:
Now, on to the information you’re looking for in the quote itself.
Important parts of a solar quote
Here are the important things to look at when you consider each quote:
- Proposed system size
- Cost per watt
- Incentives
- Energy production estimates
- Projected electricity rate increases
- Solar panel brand and model
- Panel degradation rate
- Financing
- Warranties
Let’s break down what you’re looking for with each one.
System size
System size refers to the kilowatts (kW) of power the solar installation can generate under full sun. The average size of a home solar system in the United States is about 6 kW, but differences between homes can cause that number to vary quite a bit.
The biggest factor that determines how many solar panels you need is the type of space heating, water heating, and cooking your home uses. If your home has an electric furnace and central air conditioning, you’ll need a larger solar installation than someone with a gas furnace and no A/C.
Tip: Your installer should be able to tell you exactly why they chose the size of the installation they quoted, either based on the amount of electricity you use in a year or the available space on your roof. Utilities in some places limit the size of a solar installation to whichever will provide for your annual needs, while others allow you to oversize the system if you anticipate adding a new electrical appliance or EV.
What about physical size?
The average output of a residential solar panel is around 400 watts, so you need 15 of them to make a 6-kW solar installation. The physical size of each panel is about 6 feet tall by 3.5 feet wide (21 square feet), so 15 of them take up about 315 square feet on your roof.
Cost per watt
When comparing multiple solar quotes, one of the first things you can look at is a metric called cost per watt. Very simply, it is just the total system cost in dollars divided by the system’s peak-rated output size in watts.
By calculating the cost per watt, you can easily compare prices quoted for systems of different sizes. All other things being equal, a lower cost-per-watt system should provide better value over time.
For example, say that one installer is proposing a 6.4-kW system for $17,600, and another is quoting a 7.2-kW system for $19,080. One of the quotes looks more expensive up front, but some simple math reveals the truth.
The first system costs $2.75 per watt (17,600 ÷ 6,400 = 2.75), while the second system costs $2.65 per watt (19,080 ÷ 7,200 = 2.65). In this case, the second system is less expensive per watt of power generating ability.
Tip: Cost is important, and you shouldn’t choose an overpriced solar installation, BUT: ask yourself these questions: do you want to buy the cheapest car or the best one for you at a good price? Do you want to buy the cheapest house, or the best one that you can afford? Going solar is a 25-30 year commitment. Don’t choose the cheapest company. Choose the one that’s best for you at a good price.
Incentives
After cost, the next thing to look at is incentives. Every homeowner in the country who installs solar panels is offered the federal solar tax credit, which can earn you up to 30% of the cost to install solar panels back as a tax credit the year after your installation is completed.
Note that we said “offered,” not “eligible for.” The federal tax credit is what’s known as “non-refundable,” which means you can only claim it if you have a sufficient tax burden. Many solar installers won’t be clear on that fact. Speak with a trusted financial advisor to determine if you can claim the tax credit.
States, cities, and utility companies also offer solar incentives, and luckily installers are usually pretty great at ensuring you get every penny you’re eligible for because it tends to make their job of selling solar panels easier.
Finally, some incentives are paid at the time of installation or reduce the upfront cost of going solar, while others, like SRECs, are paid over time. Just make sure you fully understand how every incentive listed on the quote works for you before signing a contract.
Learn more: Complete guide to solar incentives
Energy production estimates
Solar energy production estimates are based on several factors, including:
- The system size in kW
- Your latitude and annual weather conditions
- The direction your roof faces (also called “azimuth”)
- The tilt angle of your roof
- Any shade that falls on your roof from trees, other houses, etc.
Many solar installers now use sophisticated software that assesses your roof using satellite images, LiDAR, and even drone scans of your roof. The software simulates the path of the sun throughout the year and produces a very accurate guess at how much energy a proposed system will generate.
Tip: Every installer who gives you a quote should be able to give you an accurate estimate of energy production in the first year, and they should all come close to agreement. You can check their math using a government-developed tool called PVwatts.
If one installer’s production estimates disagree with the others by a large margin (more than around 5%), they should have a very good explanation as to why.
Some installers will estimate production assuming that nearby tall trees will be trimmed or removed, which could account for differences in production estimates. The cost of tree abatement may greatly exceed the value of the potential gains in energy production, so carefully weigh the costs and benefits.
There are some valid reasons for production estimates to be slightly higher than others, even considering the same system size. Differences between solar panel brands can account for some variations, and these differences become more noticeable over time as the panels age and slowly degrade.
Projected electricity rate increases
This little number used by the installer to estimate your potential lifetime savings with solar panels could be a BIG deal if they get it wrong. The average rate of increase in electricity prices over time was about 2.9% between 1960 and 2022.
If your installer estimates your potential savings based on a number much higher than 3%, they better have a rock-solid explanation for why they are. An example of a reason that would work is a fully approved multi-year rate increase request from your state’s Public Utilities Commission. Anything less than 100% certainty that electricity rates will rise greater than historical levels is malpractice.
Solar panel brands
These days, solar panels are essentially a commodity, and the differences between them are mostly down to cosmetics, availability, and the manufacturer's financial performance. That said, there are some important differences in materials and build quality that can affect the system's performance. Make sure you know exactly which panel brand you’re getting, and the exact model number quoted.
Note: Installers have to place orders for modules months in advance, and the exact model number quoted may not be available at the time of installation. In general, installers work with two or three brands of solar panels that they can get from their distributor, so understand that the brand or model number may change between your quote and the installation time. But also be ready to compare what was quoted to the newly-proposed panels, and know that you can renegotiate pricing if the new panels aren’t as good as the original quote.
The key things to know about the differences in performance are these:
- Cell type: monocrystalline PERC solar cells are the standard technology used in the industry today, but they are exceeded in performance by the interdigitated back contact and heterojunction cells used by premium brands like Maxeon, REC, and Panasonic.
- Efficiency: The average efficiency of top solar panel brands is now about 21%. That means 21% of the photons that hit the panel get converted into electrons that flow through your wires. The maximum efficiency of a silicon solar panel is about 30%, so we’re actually doing pretty good. The only reason you should care about high-efficiency panels is if you have space constraints on your roof. The higher the efficiency, the more power output in the same physical area.
- Degradation: Every solar panel ever made will very slowly lose some of its ability to generate power over time. The best brands lose about 0.25% per year, while the industry standard is around 0.5% per year. Regardless, solar panels should keep working well for at least 25-30 years.
- Temperature coefficient: Don’t be concerned by the big math word here. This just means that the power output of a solar panel decreases as the temperature increases. Yes, solar panels work best in the cold. Again, the best brands have low temperature coefficients, while inexpensive ones suffer from slightly increased power loss when it’s hot. The difference is tiny here, amounting to only a percent or two loss in performance between the top and bottom brands.
Best brands of solar panels
When shopping for home solar, you may hear about “tier 1 solar panels.” This term simply refers to how well the manufacturing company is doing financially. The best solar manufacturers have proven they can be profitable and will stand the test of time to provide warranty service to their customers in the next few decades.
At SolarReviews, we go a step further in our analysis, with our experts ranking the top solar panel manufacturers every year. For 2023, these are the top 10 companies:
All of the brands above are considered tier 1 manufacturers, and honestly, you won’t find many brands offered by U.S. installers that aren’t on that list. Some other companies that are still up-and-coming and didn’t make our top 10 are Aptos, LONGi, Jinko, and Solaria.
Inverter and battery brands
Aside from the panels, a solar installation's other main components are inverters (required to convert DC solar power to AC use in your home) and batteries (optional but increasingly popular).
There are two main types of solar inverters on the market: string inverters, which accept the output of all the solar panels in an array, and microinverters, which take the output of only one or two panels. About half of all residential installers will install both types, and the quote they give you will include the option they feel is best suited for your home.
Learn more: Pros and cons of string inverters vs. microinverters.
Batteries are a bit of a different story because they are so new on the market. There are dozens of different brands of batteries being sold in the U.S., and there aren’t always a ton of reviews for them. You can read our guides to popular batteries from Tesla, Generac, sonnen, and LG Energy Solution.
Warranties
Warranties are a big deal when it comes to rooftop solar. These panels will be on your roof for 25 years or more, so you ought to be sure they’ll keep working or that you’ll be covered if they fail.
Solar panels from all the reputable manufacturers listed above will come with two warranties: the product warranty and the power production warranty.
A product warranty covers the panels against defects in materials and workmanship. The industry average product warranty runs for 12 years, but the best manufacturers offer 25 years of protection, with replacement or prorated payments if panels ever fail. Thankfully, the industry rate of failure is 5 in 10,000, so panels rarely fail.
A power production warranty is where the manufacturer lists the expected degradation rate of its panels over time. Solar panels are built to last for decades, but exposure to moisture and temperature fluctuations causes a slow decline in power output. The industry average degradation rate for high-quality solar panels is around 0.5% per year, meaning after 25 years, these panels can still produce around 87.5% of their rated power output. The best solar panels degrade more slowly, at around 0.25% per year, and can still output over 92% of their rated capacity after 25 years.
Installer warranties cover the installation company’s work on your property. Ideally, these warranties should cover repairs and damages incurred due to installer workmanship and roof penetrations. Typically, large installation companies offer these warranties as a way to set themselves apart from the competition, but new options for private warranty coverage from companies like SolarInsure are leveling the playing field by allowing customers of smaller solar installers to get excellent coverage for decades after installation.
Make sure you evaluate the warranties tied to each solar quote you get. Know what’s covered and for how long, and how to make a claim.
Financing
Solar panel financing is such an important topic we could write a whole article about it. Actually we did. Here’s our complete guide to solar panel financing.
If you’re not ready for a long-term reading commitment at the moment, here are the basics:
- You can pay for solar panels with cash or a loan, or let the installation company lease the panels to you instead
- Many financing companies now offer solar loans that are designed to help people go solar with no money down and pay off the cost using the savings generated by the solar installation
- It’s important to be very careful when considering a solar loan, because some of them come with hidden fees and requirements to pay a portion of the loan equal to the value of the tax credit within the first year or two
Tip: The most important thing to know about financing is this: if you’re interested in a solar loan, get both cash and financing quotes from each installer. The difference between the cash price and the financed price will tell you about the dealer fee, and allow you to make an educated decision on whether to pursue no-fee financing from a bank or credit union instead.
Bottom line: how to know when you’re ready to choose, and what happens next
After you’ve done all the work you need to compare quotes, it’s time to choose. There will probably be one company that stands out as the best, either because of their honesty, commitment to service, choice of equipment, or their price.
A great installer should make you feel like you’re getting all the important information to make a decision and be able to answer all your questions.
Don’t feel bad if there isn’t a clear choice for you. Getting solar installed represents a multi-decade commitment, either for you or the next owner of your home. It’s important to get it right, and if the quotes you get now don’t work for you, you can always try again in the future.
Once you’ve chosen, the next step is to sign the contract. Be sure to triple check everything here and carefully verify the price, equipment (model numbers and amount), warranty coverage, financing/payments, etc.
Once the contract is signed, the installer’s team will do the final engineering, submit plans and pull permits from local authorities, schedule the installation and inspections, and work with you every step of the way to be sure you know the timeline and what’s going on.
The time it takes to complete a solar installation from a signed contract to when the utility grants you permission to operate can vary depending on where you live and how busy the installer and inspection crews are. Expect a timeline of several weeks to several months.
Finally, congratulations on taking these steps along your solar journey! We hope the information presented here will help you pick the right company for you and that you’re about to begin a long, happy relationship with home solar power!
Thi Deremer
Solar Policy Analyst and Researcher
Ben Zientara is a writer, researcher, and solar policy analyst who has written about the residential solar industry, the electric grid, and state utility policy since 2013.