Rooftop Solar Panel System Cost per Watt in 2021: 5kW-7kW, 6kW-8kW

This is a good time to install a photovoltaic solar power system on your property. Residential rooftop PV solar panels cost per watt installed has been dropping and newer technology is enabling a far greater efficiency – that’s more solar energy converted into electricity for home usage – for less money.

A new asphalt shingle roof outfitted with PV solar panels

Your options for buying, leasing, Purchasing Power Agreements (PPA, see below) are expanding, and many homeowners are getting solar panels installed on their rooftops for zero down.

In this guide:

  1. Cost per Watt
  2. Total System Cost
  3. Cost Factors
  4. Rooftop Installation Considerations
  5. PV Solar Panels
  6. Buying, Leasing, and PPA Options
  7. BiPV Solar Tiles
  8. Thin-Film Solar Laminates
  9. PACE Solar Finance Program
  10. Solar System Payback Period

Cost per Watt

The national average residential solar cost per watt installed is $2.96 for a typical 5kW (approximately $14,800) to 7kW (approximately $20,720) PV solar panels system when installed by local installers, before the 26% solar investment tax credits from the federal government.

Did you know? The 26% solar tax credits have recently been extended by congress through the end of 2022. Notably, solar ITC apply to the full amount paid for the installation of a new solar panels system.

Depending on the state you live in, your quoted cost per watt can range from $2.78 to $3.22, on average, when installed by a (small) local solar panel installer, before the 26% federal tax rebate.

Note that solar investment tax credits (ITC) are being phased out, gradually, with the amount of tax credits decreasing from 26% to 22% in 2023 (the final year for solar ITC).

How Solar Pricing Has Decreased Over Time In 2008, the cost of a solar power installation was $8.82 per watt.

Average System Cost for residential PV Solar Panels installed by Local Installers:

Small Home Average Home Large Home
Home Size 1 – 2 bedrooms 3 – 4 bedrooms 5 bedrooms
System Size 5 – 7kW 7 – 8.5kW 9 – 10kW
System Cost $14,800 to $20,720 $20,800 to $25,160 $26,640 to $29,600
After Tax Credits $10,952 to $15,333 $15,350 to $18,618 $19,714 to $21,904

Note: The federal solar investment tax credit is 26% through 2022, and 22% in 2023. After the recent extension by congress, the program is slated to end on December 31st, 2023.

Solar Costs for 5kW-7kW System by State, before the 26% Federal Solar Tax Credits:

State Cost per Watt 5kW System Cost 7kW System Cost
Arizona $2.35 – $2.75 $11,750 – $13,750 $16,450 – $19,250
California $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Colorado $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
Connecticut $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Washington D.C. $2.95 – $4.25 $14,750 – $21,250 $20,650 – $29,750
Delaware $2.35 – $2.95 $11,750 – $14,750 $16,450 – $20,650
Florida $2.35 – $2.95 $11,750 – $14,750 $16,450 – $20,650
Georgia $2.75 – $3.55 $13,750 – $17,750 $19,250 – $24,850
Iowa $3.25 – $3.55 $16,250 – $17,750 $22,750 – $24,850
Idaho $2.65 – $4.25 $13,250 – $21,250 $18,550 – $29,750
Illinois $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
Indiana $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Louisiana $2.75 – $3.55 $13,750 – $17,750 $19,250 – $24,850
Massachusetts $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
Maryland $2.75 – $3.55 $13,750 – $17,750 $19,250 – $24,850
Maine $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Michigan $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
Minnesota $3.25 – $3.55 $16,250 – $17,750 $22,750 – $24,850
Montana $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
North Carolina $2.55 – $3.15 $12,750 – $15,750 $17,850 – $22,050
New Hampshire $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
New Jersey $2.35 – $2.95 $11,750 – $14,750 $16,450 – $20,650
New Mexico $2.65 – $3.55 $13,250 – $17,750 $18,550 – $24,850
Nevada $2.35 – $2.75 $11,750 – $13,750 $16,450 – $19,250
New York $2.95 – $3.55 $14,750 – $17,750 $20,650 – $24,850
Ohio $2.65 – $2.95 $13,250 – $14,750 $18,550 – $20,650
Oregon $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Pennsylvania $2.65 – $3.35 $13,250 – $16,750 $18,550 – $23,450
Rhode Island $2.75 – $3.55 $13,750 – $17,750 $19,250 – $24,850
South Carolina $2.95 – $3.35 $14,750 – $16,750 $20,650 – $23,450
Texas $2.65 – $3.25 $13,250 – $16,250 $18,550 – $22,750
Utah $2.55 – $3.15 $12,750 – $15,750 $17,850 – $22,050
Virginia $2.75 – $3.35 $13,750 – $16,750 $19,250 – $23,450
Vermont $2.75 – $3.55 $14,100 – $17,750 $19,250 – $24,850
Washington $2.75 – $3.15 $13,750 – $15,750 $19,250 – $22,050
Wisconsin $2.95 – $3.35 $14,750 – $16,750 $20,650 – $23,450

Solar Costs for 6kW-8kW System by State, before the 26% Federal Solar Tax Credits:

State Cost per Watt 6kW System Cost 8kW System Cost
Arizona $2.35 – $2.75 $14,100 – $16,500 $18,800 – $22,000
California $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Colorado $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
Connecticut $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Washington D.C. $2.95 – $4.25 $17,700 – $25,500 $23,600 – $34,000
Delaware $2.35 – $2.95 $14,100 – $17,700 $18,800 – $23,600
Florida $2.35 – $2.95 $14,100 – $17,700 $18,800 – $23,600
Georgia $2.75 – $3.55 $16,500 – $21,300 $22,000 – $28,400
Iowa $3.25 – $3.55 $19,500 – $21,300 $26,000 – $28,400
Idaho $2.65 – $4.25 $15,900 – $25,500 $21,200 – $34,000
Illinois $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
Indiana $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Louisiana $2.75 – $3.55 $16,500 – $21,300 $22,000 – $28,400
Massachusetts $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
Maryland $2.75 – $3.55 $16,500 – $21,300 $22,000 – $28,400
Maine $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Michigan $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
Minnesota $3.25 – $3.55 $19,500 – $21,300 $26,000 – $28,400
Montana $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
North Carolina $2.55 – $3.15 $15,300 – $18,900 $20,400 – $25,200
New Hampshire $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
New Jersey $2.35 – $2.95 $14,100 – $17,700 $18,800 – $23,600
New Mexico $2.65 – $3.55 $15,900 – $21,300 $21,200 – $28,400
Nevada $2.35 – $2.75 $14,100 – $16,500 $18,800 – $22,000
New York $2.95 – $3.55 $17,700 – $21,300 $23,600 – $28,400
Ohio $2.65 – $2.95 $15,900 – $17,700 $21,200 – $23,600
Oregon $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Pennsylvania $2.65 – $3.35 $15,900 – $20,100 $21,200 – $26,800
Rhode Island $2.75 – $3.55 $16,500 – $21,300 $22,000 – $28,400
South Carolina $2.95 – $3.35 $17,700 – $20,100 $23,600 – $26,800
Texas $2.65 – $3.25 $15,900 – $19,500 $21,200 – $26,000
Utah $2.55 – $3.15 $15,300 – $18,900 $20,400 – $25,200
Virginia $2.75 – $3.35 $16,500 – $20,100 $22,000 – $26,800
Vermont $2.75 – $3.55 $16,500 – $21,300 $22,000 – $28,400
Washington $2.75 – $3.15 $16,500 – $18,900 $22,000 – $25,200
Wisconsin $2.95 – $3.35 $17,700 – $20,100 $23,600 – $26,800

Homeowners take note: large solar installers with national presence like SunRun and Vivint Solar (acquired by SunRun in 2020) will have higher costs per watt installed vs. a small local solar installer due to much higher marketing and customer acquisition costs for large installers with national presence.

SunRun and Vivint Residential Solar PV system cost per watt installed. Source: Corporate filings

Based on the recent data from the US National Renewable Energy Laboratory (NREL),
the average price per watt installed by Vivint and SunRun in 2020 has been ranging between $4.00 and $5.00 per watt. In fact, SunRun’s and Vivint prices per watt installed have increased in 2020 over 2019 due to higher marketing costs in 2020.

Did you Know? Data compiled by the International Renewable Energy Agency (IRENA) shows that the cost of PV solar energy has dropped by 73% since 2010 and is expected to drop even more in terms of panel pricing and efficiency.

Pro Tip: Find additional cost savings in your area. Many energy companies and state programs offer local energy efficiency rebates and tax credits for the installation of renewable energy equipment.

Solar power systems most definitely qualify. Call your local energy provider or search the Database of State Incentives for Renewables & Efficiency.

Factors that Affect Solar Power System Cost

Your solar panel system cost will be determined by:

System size: Your solar power contractor will take several factors into consideration when sizing the system. The number of bedrooms in a home allows a rough estimate. How much sun your climate experiences, your home’s longitude, and latitude and how panels must be placed directionally on your roof will be considered.

Roof issues: You’ll see slightly higher installation estimates for second-story roofs (or higher), ceramic/concrete tile roofs, slate and similar materials that make mounting the panels difficult.

Where you live: Cost of living realities affect solar power system prices, just as they affect the price of all consumer goods. This representative chart gives you an idea of varying costs across the country. The current national average cost is $2.96 per watt.

Three Important Solar Panel Installation Considerations

Is your roof suitable for PV solar panels installation? Let’s examine three factors that will determine whether your current roof is a good candidate for a solar power system:

  1. Age of the Roof

It wouldn’t make sense to paint a classic car without first replacing rusted-out panels, right? It’s similar with a roof. The warranty on most solar panel systems is 25 to 30 years.

While panels can be removed to allow for re-roofing a home, that’s often too expensive to be reasonable. It’s more cost-effective to install PV panels on a roof at the time of replacement.

Pro Tip: Make sure that your roof will last the lifetime of a solar power system to avoid costly solar panel removals and re-installations to accommodate for the installation of a new “in-between” roof.

How to prepare the rooftop for going solar: https://www.roofingcalc.com/roof-issues-to-address-before-installing-solar-panels/

For existing roofs, consider solar panel installation on:

Pro Tip: You can “cheat” 5-10 years on this if you’re willing to replace your solar equipment sooner than 10-20 years. You might consider that as an option for this reason: The solar technology that will be available in 15-20 years promises to be far more efficient (more solar energy per the size of the panels), lower in cost and probably better looking, too!

  1. The Weight of Existing Roofing Materials

Asphalt shingles weigh 1.5 to 4.5 pounds per square foot. If you add a second layer of shingles, your roof might not be able to support solar panels and mounting equipment. This might be a more serious issue where heavy snow loads are common.

PV Panels and their mounting brackets weigh an average of 3-4 pounds per square foot. With the heaviest shingles considered, that’s a total of 12-13 pounds per square foot. — This is another reason to consider removing old roofing materials before installing solar panels. The weight will be far less, and removing old roof material is a good time to inspect and repair a roof deck.

Why Standing Seam is Ideal for Mounting PV Panels: https://www.roofingcalc.com/why-standing-seam-solar-metal-roof-beats-tesla-solar-roof/

Did you know? Most building codes allow for up to 15 pounds per square foot of roofing material. However, if the roof has been damaged by water or excess humidity, or if it is quite old, it might sag under a load of even 8-12 pounds per square foot.

Pro Tip: Have a certified structural engineer inspect your home’s roof structure including any bracing that’s been added in the attic. And if you’re also replacing your roof before the solar system installation, consider steel standing seam. It combines the lightweight strength to support solar panels and the longevity to outlast them.

  1. Whether your Roof Gets Enough Sun Exposure

The ideal roof for solar is one facing south with enough slope to properly tilt the panels and enough room for them.

We recommend using the amazing Project SunRoof by Google to see if your home is economically suitable for going solar.

A west-facing roof is second-best ahead of an east-facing roof.

If you have a flat or low-slope roof, brackets can be installed to give your panels proper tilt. Some panels can be effectively installed on walls, though you might not like the looks of that.

A solar energy contractor can quickly determine whether your roof is a good candidate for a solar power system or what alterations to the roof or system will improve its performance. Significant alterations might increase your cost beyond the averages given above.

Solar Roof Options when Re-roofing Your Home

If you’re tearing off the old roof to start fresh, you have multiple solar roof options to consider. These include conventional PV solar panels and a new category of PV products called building integrated photovoltaics, or BIPV. Buying, leasing and PPAs expand your options.

Here are top options and details to consider:

Conventional PV Solar Panel Systems:

First Solar is one of the leading manufacturers of PV solar technology. It currently offers Series 4 and Series 4A PV 122.5-watt modules, and Series 6 420-445 watt modules. Both products have an efficiency rating of 17% and meet extended durability tests such as Thresher and Long-term Sequential.

First Solar modules are backed with a 10-year product warranty plus a 25-year linear performance warranty that guarantees a degradation rate of just .5% each year. Starting at 98%, that means the system will make at least 85.5% of that power in year 25.

Other leading brands to consider include SunPower (16-22%), LG (16.8-21%) and Panasonic (19-21%).

There are other high-quality brands. The more important consideration is finding an experienced solar contractor to install and properly set up the system for maximum performance.

Buy/lease/loan/PPA options:

Sunrun solar has a unique approach. Its motto is “solar your way.” The company doesn’t manufacture solar equipment. Instead, a consultant from Sunrun evaluates your home’s energy usage and assists you in tailoring a system to suit your requirements.

The solar power system can be purchased or leased. Another alternative is known as a PPA or power purchase agreement. Sunrun installs a solar power system on your roof at its cost.

The power it makes is pushed to the grid, and Sunrun is compensated for it. Then, the company sells you power at about 80% of what it would typically cost, so there’s a 20% savings.

Sunrun has connected almost 200,000 home and business owners with the best solar equipment for their purposes. It says current costs are $3.63 to $3.75 per watt after tax credits, or $15,000 (4kW) to $29,000 (8kW) for most homes.

Vivint Solar offers the same services as Sunrun. It also provides loans for solar in a limited number of states. See Paying for your Solar Power System below for additional options.

Building integrated photovoltaic (BiPV Solar Tiles) systems:

Tesla Solar Roof are the brainchild of Elon Musk, the man behind the Tesla electric vehicle and the SpaceX spacecraft company.

Tesla smooth solar glass tile roof. Source: Tesla

Tesla tiles are tempered glass with a lifetime warranty. Two types of glass tiles are made: Solar tiles equipped with a solar cell and non-solar tiles.

Tesla states that its roof will cost $24-$28 per square foot * 1.5 (Tesla has recently increased the price by at least 50% and nullified thousands of signed contracts between Tesla and homeowners), though the exact figure continues to change as the tile design has undergone multiple iterations and the total cost of the system has recently increased by a whopping 50% to 100%. The production of new tiles is supposedly underway, but the product availability remains uncertain.

Note: Tesla solar tiles are not really a viable product as of yet. Only a handful of these roofs have been installed so far. Future product availability guidance is murky at best and we don’t know if we’ll see the market ready Tesla solar tiles any time soon.

3 IN 1 ROOF BIPV solar tiles are covered here. These innovative roofing tiles are made from closed-cell polyurethane foam topped with a cementitious coating.

3 in 1 ROOF – classic solar tile roof

The tiles prevent heat gains inside your attic. When your attic stays cooler in summer, the home beneath requires less air conditioning. Total energy savings of up to 38% are built into the roof in this way.

Additionally, when you’re running the AC less, the size of the solar power system can be reduced. If, for example, you install a Tesla roof and need an 8.5kW system, you might only need a 7kW system with a 3 IN 1 ROOF.

A 3 IN 1 ROOF is expected to cost about $27.00-28.00 per square foot installed. Both solar tiles equipped with a solar cell and non-solar tiles are produced.

Like a roof employing traditional solar panels, Tesla and 3 IN 1 solar tile roofs require an energy storage battery and converter. The percentage of solar and non-solar tiles a home requires for either product is determined by many factors including climate, home size and roof configuration.

CertainTeed Apollo II is a BiPV system employing monocrystalline solar cells with a 60-watt per cell power rating.

Apollo Tile II Hero 2

CertainTeed claims this is, “the most energy per square foot of any BiPV solar tile”. The standard Apollo II is a solar shingle that blends fairly well with asphalt shingles.

The Apollo Tile II features the same technology in a tile designed to blend with flat concrete tiles. Both install directly on your roof sheathing with standard deck screws.

Apollo II cost is not publicly known at present but rumored to range from $30 to $60 per square foot installed, with various factors involved. At that price, Apollo II shingles and tiles cannot compete with Tesla (note: Tesla solar tiles are not a widely available product as of yet. Long term viability is currently unclear) and 3 IN 1 ROOF, so expect CertainTeed to drop the price significantly overtime, or get out of the solar tile industry.

CertainTeed does make standard solar panels, the CertainTeed Solstice line that offers a choice of mono- or polycrystalline panels. Black or silver framing and black or white backsheet are options, plus either string or microinverters.

PowerHouse solar shingles are the creation of Dow. The product had a good run starting in 2009 before being discontinued in 2016 Dow Chemical pulled the curtain on their PowerHouse solar shingles.

PowerHouse 3.0 BIPV solar tiles by RSG

Perhaps it was ahead of its time. However, the technology had been licensed to a solar energy company RGS (Real Good Solar) that was based in Denver, CO.

POWERHOUSE 3.0 BIPV Solar Roof

Unfortunately, RSG had filed for bankruptcy in 2020.

SunTegra BiPV Solar Shingles and Tiles
SunTegra products are available now. They offer similarities and differences to the competitors.

Like the Tesla, Apollo II and POWERHOUSE products, SunTegra is a two-in-one roof – solar energy production and roofing protection for your home.

SunTegra Shingles

SunTegra shingles are designed to blend well with asphalt shingles.

SunTegra Tiles

SunTegra Tiles are about the same thickness as flat concrete tiles and wouldn’t look out of place with thick architectural asphalt shingles like Carriage House from CertainTeed.

CertainTeed CH Stonegate Gray Architectural Shingle Profile

SunTegra tiles and shingles are different and unique among these products in that they feature a built-in lower venting structure called TegraVent. It allows airflow beneath the monocrystalline silicon solar panels. This prevents them from overheating and losing efficiency.

The SunTegra shingles are up to 15.9% efficient, the best for BiPV solar shingles in this comparison. The 15% for tiles is better than most, though still below the low end of the 16% to 22% efficiency that high efficiency monocrystalline PV solar panels from the likes of LG and SunPower can achieve. SunTegra’s 130mph wind warranty is the best in this group.

Thin-Film Solar Laminates:

Fabral Flex-02NS is a solar solution for metal roofing. Fabral uses the MiaSolé Flex Series (PDF). MiaSolé, a US company, is a world leader in thin-film solar technology.

Fabral preinstalled thin-film PV solar laminates

The flexible panels are ideal for a range of Fabral metal roofs. The panels are installed at the factory to ensure straight, centered lines. No penetrating fasteners are used.

MiaSolé uses copper indium gallium selenide (CIGS) thin-film technology for low-profile installation. Fabral claims efficiency of 13.2-17.3%. Warranties are 5 years on workmanship with a 25-year warranty against the degradation of efficiency.

Paying for your residential PV Solar Power System

If you’re applying for a loan to cover the cost of your system, there is a unique opportunity you should be aware of. It’s called PACE.

PACE is the Property Assessed Clean Energy Program PACE “programs allow a property owner to finance the up-front cost of energy or other eligible improvements on a property and then pay the costs back over time through a voluntary assessment.”

The amount of the monthly payment is determined using an energy assessment of the cost savings from using solar.

In short, PACE funds the purchase of the system. In most cases, the amount of energy cost saved annually is sufficient to make the loan payments.

The PACE program works with private lenders that agree to tailor loans to fit PACE guidelines. Use this map to find a PACE lender.

Did you know? The unique characteristic of PACE is that the loan is attached to the property rather than an individual.

When the home is sold, the new owner agrees to continue with the payments until the loan is paid off. The seller is no longer attached to the loan.

Solar Energy System Payback Period

The payback period of solar is the time it takes to recoup your investment through electricity cost savings.

As the cost of solar energy has dropped, so has the payback period. Let’s determine payback period for a net zero home – one in which the annual cost of electricity from an energy company is $0.

According to the most recent data from the US Energy Information Agency, the average monthly electric cost for US homes is $112.59, or $1,351.08 annual cost.

We’ve listed the average per watt cost of a solar power system as $2.78 to $3.22 per watt, or $2,780 to $3,220 per kilowatt (kW) when installed by a small independent installer.

The average system size is about 7.5kW, so the average time it takes for a solar power system to pay for itself is 8 to 10 years.

If you like crunching the numbers, this chart has monthly electricity cost data for all 50 states. It will allow you to calculate the payback period for solar energy systems where you live.

Did you know? There is a second “payback period” discussed in solar energy. Many, including popular solar energy websites, confuse the two.

The second use of “payback period”, according to the NREL, answers the question, “How long does a PV system have to operate to recover the energy—and associated generation of pollution and CO2—that went into making the system, in the first place”?

The answer given by the NREL is 1-4 years depending on the solar cell type. If you read that “a solar energy system will pay for itself in 4 years or less,” that author has confused the two payback period definitions.

While the second payback period is an important environmental question, it has nothing to do with the economics of installing a PV solar energy system on your rooftop.

Net metering: This is essential to making your payback period as short as possible. With net metering, you are charged for electricity used from the grid and paid for excess electricity you generate that is pushed onto the grid.

Here’s more on net metering from the Edison Electric Institute, or you can contact your energy provider for details. 41 states now have mandatory net metering regulations.

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