SunPower and LG Solar panels: 2020 comparison

In the premium solar panel market, SunPower and LG Solar are two of the heavyweights. With high performance and great warranties, either is a great choice for your home. Here’s the lowdown on their product lineups.

Side-by-side comparison of SunPower and LG Solar panels

Homeowners planning to add solar often have a problem of limited roof space. To work around that, solar installers often turn to the highest performance panels so that a solar array can generate more power with fewer panels.

Two of the biggest companies in the high performance end of the home solar market are SunPower and LG Solar. You might recognize the name SunPower, but be surprised to learn that LG Solar is a division of LG Electronics, the South Korean electronics behemoth that makes everything from smartphones to TVs to refrigerators. They even made tractors at one point!

If you get multiple solar quotes (like you should) there’s a pretty decent chance that you’ll end up with one proposal with SunPower panels and another with LG panels. This guide will explain the product offerings from the two companies and help you decide between them.

Company overviews: LG Solar and SunPower

LG is a South Korean company that was started in 1958 under the name GoldStar. It began research and development on solar cells back in 1985, but didn’t enter the solar panel market until 2010. It recently opened a factory in Huntsville, Alabama, where it manufactures its NeON panels. It also does manufacturing in South Korea.

SunPower is an American company that was started in 1985 as a solar thermal manufacturing company. In recent years, SunPower has had financial troubles, and in 2020 started the process of spinning off its manufacturing segment to a new company called Maxeon.

The restructured SunPower will focus on the solar installation market in North America, while Maxeon will operate as a separate company headquartered in Singapore. Freed from the cutthroat solar manufacturing business where competition is global and margins are razor-thin, the new SunPower hopes to be in a better financial position going forward.

Maxeon will take over SunPower factories located in Malaysia, Mexico, the Philippines and France. Ironically, this means if you want to buy American-made panels, you would do that by buying from a South Korean company rather than a American one.

Product overview

Both LG and SunPower have competing products in the following categories: high performance panels, lower cost panels, all-black panels, and AC panels that come with microinverters. It can be a little confusing to figure out the different model numbers from the LG and SunPower websites, so here’s a table:

High performanceNeON RX-Series
Lower costNeON 2E-Series
All-blackNeON R Prime
NeON 2 Black
X-Series Signature Black
AC panelNeON R ACeA-Series

There are even more products offered by both companies (such as LG’s two-sided bifacial panel), but the product categories listed above are the ones that are most commonly used in residential applications.

Crash course in solar panel specifications

Before we jump into the product listings, it’s worth reviewing a few technical concepts that will be mentioned.

Efficiency is a measure of how much of the light hitting the panel gets converted into electricity. Higher efficiency is better because it means you’ll need fewer panels to achieve the same the output.

The power temperature coefficient is important because solar panels perform better when cold, and lose efficiency when they get hot (like when they’re sitting under a hot Arizona sun). The numbers listed in the tables below show you how much power output is reduced for every 1°C increase in temperature. For example, a panel with a power temperature coefficient of -0.50%/°C loses 0.50% in power output for every 1 degree C increase in temperature.

Finally, the warrantied output after 25 years is what the manufacturer guarantees the power output of the panel to be after 25 years, as a percentage of the output when the panel was new. Solar panels last a very long time, but they do naturally degrade, losing a little bit of power output every year. Panels that are expected to degrade less will have a better warranty. Cheaper panels might be warrantied to produce 80% of their original output after 25 years, but high end panels will be 90% or better.

Those are the key specifications we’ll highlight in this article, but if you want to understand more, you can read our article on understanding solar panel specifications.

High performance: LG NeON R vs SunPower X-Series

At the high end of the product lineup for these companies are the LG NeON R series and the SunPower X-Series panels. With these panels, SunPower and LG use their best technology to maximize efficiency and power output. Both the NeON R and X-Series use rear contact solar cells to increase power output.

In a conventional solar cell, there are fine wires called busbars and fingers that form a visible grid on the front of each cell. Having lots of wires reduces power loss because electrons in the silicon cell don’t have to travel as far to reach a conductive wire, but at the same time this increases power loss because the metal wires block sunlight from reaching the photovoltaic material underneath.

By moving the wiring to the rear of the cell, these shading losses are eliminated. SunPower takes this to the extreme with the Maxeon line of cells used in the X-Series by not using individual wires but a solid sheet of copper on the rear of each cell. In addition to increasing efficiency, SunPower claims that this makes the cell stronger and increases its lifespan.

In the end, both the LG and SunPower panels end up with greater than 21% efficiency, placing them at the high end of performance among all panels on the market.

Key specifications

LG NeON RSunPower X-Series
Maximum output370 Watts345 Watts
Efficiency (higher is better)21.4%21.5%
Power temp. coefficient (lower is better)-0.30%/°C-0.29%°C
Warrantied output after 25 years (higher is better)90.8%92%

You might notice that the LG panels have a higher maximum output. This isn’t due to higher efficiency, but because the NeON R panels are slightly larger.

As you can see, the X-Series outperforms the NeON R in all three categories, but only very slightly. The performance is close enough that you can consider these panels to be equal, which means that other considerations - particularly price - should be the deciding factor. On a tight roof, the slight difference in panel size might also be a factor.

Lower cost panels: LG NeON 2 and SunPower E-Series

One step down from the high end of the product range are the LG NeON 2 and SunPower E-Series. We’ll call them “lower cost” panels, but both but the LG and SunPower products in this category are still very high performance, and significantly outperform panels from other manufacturers that truly fall into the budget category.

Key specifications

LG NeON 2SunPower E-Series
Maximum output360 Watts327 Watts
Efficiency (higher is better)20.8%20.4%
Power temp. coefficient (lower is better)-0.34%/°C-0.35%°C
Warrantied output after 25 years (higher is better)90.1%92%

As you can see, these panels have higher than 20% efficiency, which means they still offer better performance than the best panels offered by some other manufacturers.

The LG panel has the edge in initial performance (20.8% efficiency vs 20.4%), but as the panels age the SunPower panel may perform better, as it’s guaranteed to retain 92% of its original output after 25 years, versus 90.1% with the LG panel.

Just as with the panels in the high performance category, these lower cost panels from LG and SunPower match up against each other very well. As a shopper, the decision may come down to price.

One difference worth mentioning is that the NeON 2, unlike the high end NeON R, does not use rear contact cells and has visible wires on the front of the cell. This means that a faint grid will be visible on the LG panel. The E-Series panel uses Maxeon cells with a copper sheet on the rear on the cell, just as the X-Series does, which means that the SunPower panel has a slight edge when it comes to aesthetics. This won’t matter to many people. However, if your panels are installed on a part of your home where curb appeal is affected, this slight difference may be important to you.

All-black panels: LG NeON R Prime, NeON 2 Black, and SunPower Signature Black

For maximum power output, installers generally try to place solar panels on south-facing roofs. If the southern segment of your roof happens to face the curb, then you will want to think about the aesthetics of your system because curb appeal is a big factor in the value of your home.

Solar shingles have gotten some buzz lately because of the Tesla Solar Roof, but the product idea isn’t new. It’s struggled to find traction in the market, with vendors such as RGS recently declaring bankruptcy. Even Tesla has had trouble ramping up production.

If aesthetics are important to you, it’s better to stick with conventional solar panels, which are a very mature technology that can be serviced by any licensed professional. Solar shingles, on the other hand, are proprietary and are supported only by the manufacturer. If the company goes out of business, like RGS has, you’ll be in big trouble if your system needs service.

Because of this, sleek all-black solar panels are a much better choice.

LG NeON R Prime all-black solar panel
LG NeON R Prime all-black solar panel.

LG offers the NeON 2 Black (based on the NeON 2 series) and the NeON R Prime (based on the NeON R).

SunPower has the Signature Black series, which is based on the X-Series.

All-black solar panels use a black backsheet - that’s the layer that the individual solar cells are mounted on - and a black aluminium frame. Standard panels use a white backsheet because it helps the panel to stay slightly cooler. (In the specifications section above, we learned about power temperature coefficients.) This means that all-black panels pay a penalty in lower power output, but the effect is small - only 5 to 10 watts per panel.

If your panels will be facing the street, the tiny financial loss due to slightly lower electricity production will probably be far outweighed by the better curb appeal of all-black panels.

AC panels: LG NeON R ACe and SunPower A-Series

All solar panels produce direct current (DC) electricity, but your home is wired for alternating current (AC). It’s the job of a solar inverter to convert DC-to-AC power, and this is usually a standalone component in a solar system.

However, many manufacturers have started selling AC solar panels. These aren’t panels that produce AC power directly, but instead they pair one of their standard solar panels with a microinverter and sell it as a single unit.

This has some advantages. First, there’s less work for the installer because the step of mounting and wiring the inverters is already taken care of. Installers strive to get the installation work done in a day or less, because multiple trips to your home means extra driving time, and every hour counts when it comes to labor costs. If your installer can save money on labor, they can pass that savings onto you.

Another potential advantage comes from hardware cost savings due to the panel and microinverter being supplied together.

However, AC panels aren’t always the best solution. One disadvantage is that the monitoring software may be specific to that manufacturer, which ties you to that company if you need to repair or upgrade your solar system. If your system is based on microinverters from a separate manufacturer - such as Enphase - you can add more panels in the future from any manufacturer.

SunPower A-Series panel with integrated microinverter.
SunPower A-Series panel with integrated microinverter.

SunPower offers the A-Series AC panel, which uses the same solar cells as the X-Series and has similar specifications.

LG has the NeON R ACe panel, which is based on the NeON R series.

It’s not clear whether LG and SunPower manufacture their own microinverters for these panels or have rebranded inverters from a supplier. For example, it’s known that Enphase and SunPower have a partnership, but their literature doesn’t say whether the A-Series uses Enphase technology.

Bottom line: your choice may come down to price and installer choice

If you compare the product offerings of these two companies, you’ll see that they stack up very favorably against each other. While there are slight differences in performance between panels in each of these product categories, they aren’t large enough to base your product decision on.

Instead, if offered a choice, you can probably safely make your decision based on the best price.

Another consideration is that both SunPower and LG offer certifications for installers who have met certain criteria, such as training requirements and having a good track record with a sufficiently high volume of installations.

SunPower has Authorized Dealers for companies that have met minimum requirements for training and customer satisfaction, and Elite Dealer and Master Dealer designations that meet more stringent standards.

LG, meanwhile, has LG PRO and PRO Platinum designations for their certified installer network.

If your installer has one of these certifications, that’s a good sign, and it should factor into your decision if you’re choosing between these two manufacturers.

One last consideration: if buying American-made products is important to you, find out from your installer if they can tell you if your LG NeON panels were sourced from the Alabama factory or overseas. Ironically, it’s the South Korean LG and not the US-based SunPower that does any manufacturing in America.

#LG #SunPower

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