Thinking of Installing Solar Panels? Pay Attention to the Solar Panel’s Warranty

Like most technology products that you buy, solar panels come with warranties that help safeguard your investment in the unlikely event that a problem occurs after installation. When evaluating solar panel manufacturers, the two most important warranties on which you should focus are:

1. Product (or materials) warranty, and
2. The performance warranty
.
We’ll address both of these in this article.

1.  What is Solar Panel Product Warranty?
A solar panel’s product warranty covers the integrity of the panel itself, and protects you against failures due to manufacturing defects, environmental issues, premature wear and tear, etc. Most solar panel manufacturers warrant that their panels will not fail for at least the first 10-12 years, and some extend their warranty periods even longer than that. As with most warranties, a longer period is generally more advantageous to you, if you own your solar panel system.

Why Does a Solar Panel’s Product Warranty Matter?  How Should it Impact Your Decision.
If you install a solar PV system for your home or business, by far your most likely scenario is that your panels will perform trouble-free for decades. But problems do occur from time to time, so if you happen to experience a problem with a solar panel after it’s been installed, it’s important for you to understand that the rest of your system will not be rendered inoperable—not by a long shot. In all likelihood, depending on the nature of the panel failure, the rest of your system will just continue running with the failed panel left in place. But occasionally panels fail in ways that impact the performance of neighboring panels. In either case, it’s the panel’s product warranty that will cover you if you ever need to get a bad panel swapped out for a new one.  A point to note, the cost of a single solar panel generally ranges from $150 to $300.

Evaluating and comparing the product warranty coverage of panel manufacturers can help assure you that your service and support needs will be covered if a solar panel problem ever occurs. Manufacturers’ product warranties are therefore an important complement to other considerations in assessing not only a panel manufacturer’s technical specifications, but also its business practices.  In case a solar panel fails, the manufacturer will ship you a replacement panel and in some cases, even pay for shipping cost and labor cost to replace it.

How the Top Solar Panel Manufacturers Stack Up
The Exhibit 1 below summarizes the product warranty duration for the leading manufacturers who sell solar panels in the U.S.  Most manufacturers offer a 10-year product warranty from the date of installation.  Only SunPower offers a product warranty of 25 years.  On the other hand, only Hyundai seems to offer just a 6-year product warranty for its panels.

Exhibit 1:  Solar Panel Product Warranty by Manufacturer

 

Duration of Product Manufacturer Warranty

Solar Panel Manufacturer

6 Years

10 Years

25 Years

1SolTech

Aleo

Axitec*

√  *

Canadian Solar

Centrosolar

Conergy

Eoplly

ET Solar

Hanwha SolarOne*

√  *

Hyundai

Itek

KYOCERA Solar

LG

Lightway

MAGE Solar

Perlight Solar (Zebra Energy)

Phono Solar

REC Solar

ReneSola

Sharp Solar

SolarWorld

SunEdison/MEMC

Suniva

SunPower

Suntech

Trina Solar

Winaico*

√  *

Yingli Solar

* 12-year product warranty

 

2.  What is Solar Panel Performance Warranty?
The amount of electricity a solar panel produces declines slightly every year. That’s true of all solar panels, but to varying degrees. A common practice in the solar energy industry is to guarantee that the panels will not lose more than 10%-20% of their power output capacity over the first 25 years. Said another way, panel manufacturers generally guarantee that their panels will produce electricity at 80%-90% of their power output rating at the end of 25 years.

Why Does a Solar Panel’s Performance Warranty Matter?  How Should it Impact Your Decision.
A solar PV system represents a multi-decade investment. Your return on that investment is directly related to the amount of electricity your solar energy system generates year-after-year.  The electricity generated by your solar panel system allows you to either buy little or no electricity from your utility. The less energy your solar system produces, the greater your dependence on the utility. It’s a zero-sum game. If the panels in your solar system degrade quickly over time, then you’ll derive less long-term value from your system than if your panels degraded more slowly.

Performance warranty coverage is yet another indicator of a panel manufacturer’s service and support policies in the event that you ever encounter a problem with your solar system. Whereas product warranty issues are fairly straightforward to demonstrate (either your panel is working or it’s not), proving that you’re experiencing a panel performance problem that should be covered by warranty can be far more subtle, the reasons for which are beyond the scope of this brief article. Suffice it to say that higher 25-year performance warranties (i.e., slower degradation) are viewed more favorably than lower performance warranties, but as a practical matter the performance warranty may be a better indicator of a panel’s intended degradation behavior than of its manufacturer’s support practices. If your solar panels degrades faster than what the warranty specifies, the manufacturer will either repair the solar panel or provide you with a replacement panel.  Some manufacturers even pay to ship the solar panel to you and labor cost to replace the panel.

How the Top Solar Panel Manufacturers Stack Up
The Exhibit 2 below summarizes the 25-year performance warranties for the leading manufacturers who sell solar panels in the U.S. market.  As you can see, most manufacturers warranty a 80% performance output after 25 years., with some manufacturers doing somewhat better than that.

Exhibit 2:  Solar Panel Performance Warranty by Manufacturer

 Solar Panel Manufacturer

25-Year Performance Warranty

1SolTech

N/A

Aleo

80.0%

Axitec*

85.0%

Canadian Solar

80.0%

Centrosolar

80.2%

Conergy

80.0%

Eoplly

80.3%

ET Solar

81.4%

Hanwha SolarOne*

80.2%

Hyundai

80.0%

Itek

80.0%

KYOCERA Solar

80.0%

LG

81.2%

Lightway

80.7%

MAGE Solar

80.0%

Perlight Solar (Zebra Energy)

80.0%

Phono Solar

80.0%

REC Solar

80.2%

ReneSola

80.0%

Sharp Solar

80.0%

SolarWorld

80.2%

SunEdison/MEMC

79.7%

Suniva

80.2%

SunPower

89.0%

Suntech

80.2%

Trina Solar

80.7%

Winaico*

80.2%

Yingli Solar

81.1%

To learn more about solar panel product and performance warranties as well as other criteria to evaluate solar panels, see our research on how to select solar panels.

What is the Power Output of a Solar Panel?

You may hear your solar installer say “it’s a 255 Watt panel” or “the panel I am recommending is a 300 Watt panel” or when you are reading a quote from a solar installer and see numbers like 245 or 300W or 345W next to the name of the panel.  They are all referring to a solar panel’s power output.

All solar panels are rated by the amount of DC (direct current) power they produce under standard test conditions. Solar panel power output is expressed in units of watts, and represents the panel’s theoretical power production under ideal sunlight and temperature conditions. Most solar panels on the market today have power output ratings ranging from 200 to 350 watts, with higher power ratings generally viewed as being more favorable than lower power ratings.

Why Does Solar Panel Power Output Matter? How Should it Impact Your Decision?
When you buy or install a solar photovoltaic (PV) energy system for your home or commercial property, the price you pay is typically based on the total power output of the solar panels in the system (expressed in watts or kilowatts), whereas the financial savings you derive from the solar system stems from the electric energy that it generates over time (expressed in kilowatt-hours).

Size of Panels vs. Number of Panels
Power output on its own, however, can be an incomplete indicator of a panel’s quality and performance characteristics. Some panels with a high power output rating are due to their larger physical size rather than their higher efficiency or technological superiority. For example, if two solar panels both have 15% efficiency ratings, but one has a power output rating of 250 watts and the other’s power output is rated at 300 watts, it means that the 300-watt panel is about 20% physically larger than the 250-watt panel. That’s why EnergySage and other industry experts view panel efficiency as being a more indicative criterion of solar panel performance strength than power output alone.

In practical terms, a solar panel system with a total rated capacity of 5kW (kilowatts), will need 20 250-Watt panels or 16 300-Watt panels.

Both the systems will generate the same amount of power in same geographic location.  Though a 5kW system may produce 6,000 kWh (kilowatt hours) of electricity every year in Boston, while it will produce 8,000 kWh every year in Los Angeles because of the amount of sun each location gets each year.  (Read our blog on how electricity production and electricity prices you pay to your utility impacts your savings)

The electricity generated by a solar PV system is governed by its rated power output, but it’s also dependent on other factors such as panel efficiency and temperature sensitivity, as well as the degree of shading that the system experiences and the tilt angle and azimuth of the roof on which it’s installed. As a general rule of thumb, it makes prudent financial sense to install a solar system with as much power output as you can afford (or that your roof will accommodate). That will ensure you maximize your savings and return on investment and speed up payback period of your solar energy system.  The EnergySage Solar Marketplace makes it easy for you to easily compare your savings from solar panels that vary in their power output ratings.

How the Top Solar Panel Manufacturers Stack Up
The two Exhibits below present different views of the power output characteristics of the leading manufacturers who supply solar panels to the US market. Most panel manufacturers produce more than one line of solar panel models. Exhibit 1 illustrates the range of each manufacturer’s panel offerings from the standpoint of power output, whereas Exhibit 2 lists the minimum, maximum, and average power outputs of the solar panels within each manufacturer’s portfolio.

Exhibit 1:   Range of Power Output of Solar Panel Manufacturers

Solar Panels Power Output 

Exhibit 2 Power Output (in Watts) of Solar Panels Manufacturers

Solar Panel Manufacturer

Minimum

Maximum

Average

1SolTech

210

350

279

Aleo

220

350

273

Axitec*

240

300

261

Canadian Solar

200

305

249

Centrosolar

245

305

261

Conergy

245

310

263

Eoplly

190

305

255

ET Solar

200

315

263

Hanwha SolarOne*

245

305

271

Hyundai

230

305

259

Itek

230

280

268

KYOCERA Solar

140

325

245

LG

250

300

271

Lightway

200

310

258

MAGE Solar

205

310

258

Perlight Solar (Zebra Energy)

240

350

291

Phono Solar

200

325

264

REC Solar

210

325

253

ReneSola

195

310

259

Sharp Solar

200

310

243

SolarWorld

220

315

257

SunEdison/MEMC

265

335

286

Suniva

240

325

278

SunPower

255

345

330

Suntech

245

305

263

Trina Solar

230

260

244

Winaico*

190

290

248

Yingli Solar

240

310

273

To learn more about solar power output and other criteria to evaluate solar panels, see  EnergySage research titled “How to Evaluate Solar Panels

What is a Solar Panel’s Efficiency, and Why Does it Matter?

Simply put, efficiency (expressed as a percentage) quantifies a solar panel’s ability to convert sunlight into electricity. Given the same amount of sunlight shining for the same duration of time on two solar panels with different efficiency ratings, the more efficient panel will produce more electricity than the less efficient panel.

In practical terms, for two solar panels of the same physical size, if one has a 21% efficiency rating and the other has a 14% efficiency rating, the 21% efficient panel will produce 50% more kilowatt hours (kWh) of electricity under the same conditions as the 14% efficient panel.

Why Does Solar Panel Efficiency Matter? How Should it Impact Your Decision.
Many consumers and people in the solar industry consider efficiency to be the most important criterion when assessing a solar panel’s quality. While it is an important criteria, its not the only one to consider while you evaluate whether to install a particular solar panel.

The most efficient commercially available solar panels on the market today have efficiency ratings as high as 21.5%, whereas the majority of panels range from 14% to 16% efficiency rating.

Maximum Production or Maximum Offset:  If your goal is to maximize the amount of electricity your system produces or want to ensure you buy the least amount of electricity from the utility, but the amount of roof space you have available to install solar panels is limited in size, you may choose to install higher efficiency solar panels.  This will ensure you get the maximum production from your solar panel system.

Cost vs. Value:  More efficient solar panels tend to cost more than their less efficient cousins.  You may want to analyze whether that upfront cost difference is justified by the increased saving achieved by generating more electricity over the lifespan of your solar energy system. Increased electricity production means you have to buy less power from your utility and in some states, may also generate higher SREC income.  The EnergySage Solar Marketplace makes it easy for you to easily compare your savings from solar panels that vary in their efficiency ratings and if their premium price is justified.

How the Top Solar Panel Manufacturers Stack Up?
The two charts below present different views of the efficiency characteristics of the leading manufacturers who sell solar panels in the U.S.. Most panel manufacturers produce several models of solar panel models which range in efficiency ratings.

The Exhibit 1 illustrates the range of each manufacturer’s offerings from the standpoint of panel efficiency whereas Exhibit 2 lists the minimum, maximum, and average efficiencies of the solar panels within each manufacturer’s portfolio.

Exhibit 1:  Solar Panel Efficiency Ranges of Manufacturers

Exhibit 1- Solar Panel Efficiency

Exhibit 2:  Efficiency Rating of Panel  Models by Manufacturer

Solar Panel Manufacturer

Minimum

Maximum

Average

1SolTech

13.0

16.2

15.1

Aleo

15.1

17.0

16.6

Axitec*

14.8

16.0

15.4

Canadian Solar

15.5

16.6

16.0

Centrosolar

14.4

15.7

15.0

Conergy

13.7

16.0

15.1

Eoplly

13.9

15.7

14.8

ET Solar

14.8

16.3

15.5

Hanwha SolarOne*

14.2

15.8

15.0

Hyundai

14.2

16.5

15.4

Itek

15.6

17.1

16.3

KYOCERA Solar

14.0

15.2

14.7

LG

15.2

18.3

16.6

Lightway

14.2

16.2

15.2

MAGE Solar

15.3

15.4

15.3

Perlight Solar (Zebra Energy)

14.7

16.2

15.5

Phono Solar

14.4

16.8

15.6

REC Solar

14.5

16.1

15.3

ReneSola

14.1

16.3

15.4

Sharp Solar

14.4

15.3

14.9

SolarWorld

13.1

16.7

15.1

SunEdison/MEMC

13.9

17.1

15.4

Suniva

14.7

16.8

15.8

SunPower

19.3

21.5

20.6

Suntech

14.1

16.3

15.3

Trina Solar

14.1

15.9

14.8

Winaico*

14.1

17.5

15.4

Yingli Solar

14.7

17.1

15.7

To learn more about solar panel efficiency as well as other criteria to evaluate solar panels, see  EnergySage research Titled How to Evaluate Solar Panels

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