Solaria and SunPower solar panels: 2019 comparison

Just like SunPower, lesser known Solaria is an American company that makes high performance solar panels.

There’s a lot of solar panel manufacturers in the marketplace. Chinese companies, spurred by the massive deployment of photovoltaics in China, occupy most of the top 10 spots for largest solar panel manufacturers in the world.

The massive scale of the solar industry in China and Southeast Asia makes it hard for US-based companies to compete on price. Because of this, many American companies focus on the high end of the market by working to produce attractive and high efficiency cells.

SunPower is perhaps the most well-known US company in the residential solar market. It focuses on manufacturing attractive, high efficiency solar panels.

But there are lesser-known US-based companies that also focus on the high end of the market. One these is Solaria, a company founded in 2000 that has been quietly growing but has stayed small compared to it competitors.

Solaria is a private company, so its financials aren’t readily available. However, the Crunchbase profile on Solaria indicates that it has received a total of $214 million in venture funding since 2004, and employs fewer than 100 people.

SunPower, on the other hand, is a public company with close to a $2 billion market capitalization and around $1.7 billion in revenue in 2018.

Compared to SunPower, Solaria is just a minnow. And yet Solaria’s PowerXT product line has a lot of similarities to products from the more well-known SunPower. Because of this, it’s worth doing a side-by-side comparison.

Solar panel efficiency refers to how much incoming sunlight is converted to electricity. Today’s home solar panels range from 15% to almost 23% efficient.

Solaria PowerXT panel overview

Solaria has a small product lineup. For the residential market, there are just two products to choose from: the Solaria PowerXT with and without an integrated Enphase microinverter.

As far as installed appearance goes, both products look identical (because the microinverter is mounted on the rear). The PowerXT is an attractive all-black panel:

Example of a Solaria PowerXT installation. (Courtesy Solaria)Example of a Solaria PowerXT installation. (Courtesy Solaria)

If you’re familiar with SunPower products, you’ll recognize the emphasis on making the frontside of the panel completely black by moving the wiring to the rear of the solar cell. While many manufacturers also offer solar panels with black backsheets and frames, most still have visible wires on the front of the panel, preventing the panel from having a completely homogenous appearance.

In contrast, the Solaria panels look completely uniform. Here’s a closeup:

Closeup of Solaria PowerXT solar panels. (Courtesy Solaria)Closeup of Solaria PowerXT solar panels. (Courtesy Solaria)

How does Solaria achieve this appearance? Here’s how they explain it:

Solaria utilizes a unique and proprietary process for dicing and connecting solar cells into a format that enables them to be “shingled” together instead of connected with traditional bussing ribbons.

Standard modules utilize copper ribbons to interconnect all the cells in the module together by means of high-temperature soldering processes. Although this method is certainly the most common it is not the most efficient. The busbars need to cover a portion of the solar cells (as much as 3.5%) and require the cells to be spaced apart from one other. There is typically over 100 feet of ribbon per module to enable all these connections. That is a lot of copper and lot of potential failure points.

Busbars are flat, wide wires on the front of a solar cell that provide an electrical connection. A typical cell may have 2 to 5 busbars.

Fingers are thinner wires on the front of a solar cell that run perpendicular to the busbars.

Picture of an individual solar cell

Although all solar cells have very low failure rates, one of the common failure points in traditional solar cells is at solder points, where outdoor temperature swings cause expansion and contraction and, in some cases, cracking and failure.

Both Solaria and SunPower have ways of eliminating this wiring, resulting in a clean, homogenous appearance on the front of the cell.

PowerXT specifications

Here are the key specifications for the PowerXT module:

Cell typemonocrystalline
Efficiency19.6%
Power output (STC)350 to 360 watts (depending on model)
Power output (NOCT)258 to 265 watts (depending on model)
Warranty25 year power, 25 year product
Dimensions43.9" x 63.8"

STC is an efficiency rating under idealized lab conditions.

NOCT is a more realistic efficiency rating that takes into account the higher temperatures that a panel will experience in the field.

This efficiency places the PowerXT module at the higher end of performance among its competitors, but it falls short of several others, such as the LG NeON and SunPower Maxeon-based panels which reach up to 22% efficiency.

One thing to note, however, is that the PowerXT is slightly larger by a couple inches in both dimensions than most other 60 cell panels. This means that while each panel produces 360 watts - about the same as many competing produces - it achieves this by taking up a little bit more space.

PowerXT AC Module

A conventional solar panel generates direct current (DC) power. This DC power is then sent to an inverter which converts it to alternating current (AC) that your home can use.

One of the types of inverters that you can choose for your home is a microinverter. With a microinverter-based photovoltaic system, every solar panel has its own small inverter bolted on the back.

Enphase is, by far, the largest manufacturer in this space and somewhat synonymous with microinverters in the US market. You can learn more about Enphase microinverters in an earlier blog post.

Both SunPower and Solaria have released solar panels that come with an Enphase microinverter built in. This comes with a price advantage, as well as shorter installation times.

The Solaria PowerXT AC module includes an Enphase IQ7+ built in. It’s called an AC module because the panel outputs AC power instead of DC, due to the integrated microinverter.

The maximum theoretical DC output of the panel is 355 watts, but the maximum output of the IQ7+ is 295 watts. This means that in perfect sunny conditions, the panel output could be limited by the inverter in a phenomenon called inverter clipping.

In the real world, this probably won’t be a problem because the NOCT rating is 265 watts. Also, inverter clipping losses are often deliberately designed into the system, because installing a larger capacity inverter to handle the rare cases when panel output hits its theoretical STC maximum isn’t worth the additional cost.

Should you choose the AC module? I would have that conversation with your solar installer. Whether or not it saves you money depends on the price your installer is able to get from Solaria, and whether any labor savings will be passed down to you.

SunPower panels overview

SunPower has a much more extensive product lineup, so I won’t go into depth about every one.

Instead, I’ll focus on the X-Series, specifically the Signature Black because it’s the most direct competitor to the all-black Solaria PowerXT DC (non-microinverter) module.

SunPower X-Series Signature Black solar panels. (Courtesy SunPower)

SunPower X-Series Signature Black specifications

Here are the key specifications for the Signature Black:

Cell typemonocrystalline
Efficiencyup to 21%
Power output (STC)310 to 335 watts (depending on model)
Power output (NOCT)233 to 252 watts (depending on model)
Warranty25 year power, 25 year product
Dimensions41.2" x 61.4"

As you can see, the X-Series panels have slightly higher efficiency, but lower maximum output (335 watts versus up to 360 watts for Solaria). This lower output in spite of the higher efficiency of the X-Series is because the PowerXT is a larger panel by about two inches in both dimensions.

SunPower technology

As you can see, the X-Series panel also does away with the busbars and fingers on the front of the cells, resulting in a uniformly black cell. In cutting its cells, SunPower uses a more traditional technology, which is why the standard X-Series with a white backsheet shows gridlines between the individual cells, just like most conventional panels.

The Signature Black series gets rid of the white gridlines by substituting a black backsheet in place of white, at the cost of a very small loss of efficiency.

The rear of a SunPower solar cell. (Courtesy SunPower)

SunPower eliminates the front wiring by using a slab of copper on the rear of the cell. This eliminates solder points and enables stronger wiring connections, which should result in lower failure rates over time.

SunPower panels with integrated microinverters

The SunPower Equinox is their line of solar panels that include integrated microinverters. There’s little information available on their website - it doesn’t describe which series of panels they use, or what microinverter.

However, it is known that SunPower has partnered with Enphase. The Equinox also has an all-black appearance, so it’s likely that they are using their X-Series Signature Black panels.

Warranty comparison

Solaria and SunPower take different approaches to eliminating the busbars and solder points in their solar panels, which should reduce one of the main reasons for solar panel failures.

As a result, both companies offer some of the best warranties available: a 25 year warranty on both power production and the product. (Many other companies also offer a 25 year power warranty but only a 10 year product warranty.)

The SunPower power warranty is slightly better. It guarantees that it will still be producing 92% of its original power output after 25 years. In comparison, Solaria gives a 86% warranty on its panels.

This is a really minor difference, so I wouldn’t make it a factor in your buying decision.

Made in America?

Both companies are US-based, and both do some manufacturing in the United States. However, if you specifically want American-made panels, you should know that both SunPower or Solaria operate factories in Southeast Asia.

Solaria operates a factory in Fremont, California, but also does some manufacturing in South Korea.

Meanwhile, SunPower has a factory, in Hillsboro, Oregon, but that factory is now up for sale and has never operated at full capacity. Meanwhile, SunPower does significant manufacturing work in China.

In other words, if you specifically want all-American panels, you should look elsewhere such as Mission Solar, which operates entirely within Texas.

Solaria or SunPower: which is better?

Solaria and SunPower offer remarkably similar products, even though SunPower is a huge company and Solaria can almost be considered a boutique manufacturer.

Size is not necessarily better: SunPower has been in a bad financial situation for a long time, although there’s signs of improvement in recent years. Solaria, on the other hand, has opted for slow, steady growth over two decades.

Both the Solaria PowerXT and SunPower X-Series Signature Black are very similar. Both have high efficiency, excellent warranties, technology that should eliminate many wiring-related failures, and an attractive all-black appearance.

While SunPower has a very minor advantage in terms of efficiency and warranty, I wouldn’t make that a deciding factor. Instead, focus on price. Pricing can change quickly, so I would consult with a qualified solar installer to get the latest information.

However, in general Solaria will probably come in lower than SunPower. Because of this, when comparing the two companies I would give serious consideration to the PowerXT series, even though it’s the much lesser known product.

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