REC solar panels: the unofficial product guide
Among premium solar companies, REC is a lesser known brand but one that makes high efficiency solar panels that are often a relative bargain. Here's the lowdown on their product lineup.
According to Berkeley Lab, a large majority of homeowners are now choosing premium equipment for their home solar systems, including high efficiency solar panels and microinverters.
When it comes to panels, one of the brands that’s producing some of the highest efficiency solar panels is REC Group. Founded in Norway in 1996, the company went through the kind of financial difficulties that many solar manufacturers have experienced, culuminating in their acquisition by the Chinese company BlueStar in 2014.
REC Group is currently headquartered and manufactures its solar panels in Singapore.
How well do REC solar panels perform?
REC solar panels compare very favorably to products from other premium solar panel manufacturers such as LG and SunPower. In particular, REC panels perform well in the following areas:
- Panel efficiency: how much sunlight gets converted to electricity
- Temperature coefficient: how well the panels perform when hot
- Warranty duration: how many years they’re guaranteed against product defects
- Warrantied power degradation: how much power generation the panel is expected to lose at it ages
Like many other manufacturers, REC has a range of products from the high end to more budget-friendly solar panels. I’ll highlight the performance differences between them, but first let’s talk about the company’s warranty.
REC solar panel warranty: one of the best available (with a caveat)
Solar panels come with two warranties.
In the US, any solar panel that is intended for a home installation will have at least a 10 year product warranty. This warranty covers any premature failure of the panel due to product defects.
On top of that, the panel will have a 25 year power warranty. This doesn’t mean that it’s warrantied to produce power for 25 years: the guaranteed longevity of the panel is limited to the duration of its product warranty. Rather, the power warranty guarantees that, if the panel is still working, its power output won’t drop below a specified level.
REC solar panels have a 25 year power warranty and a minimum 20 year product warranty.
However, if the panel is installed by a REC-certified installer, the product warranty can be extended to 25 years and also covers labor. This is called the REC ProTrust Warranty. If you have a broken panel that needs to be replaced, other manufacturers will replace the panel but it’s up to you to pay for the installation. In many cases, the cost of labor will be higher than the panel itself.
With the REC ProTrust Warranty, the cost of labor is covered, which is a big savings.
If you’re getting REC solar panels for your home, be sure to ask if the installer is REC-certified so that you can get the extended REC ProTrust Warranty. If they advertise this on their website, look for a logo like this:
How long will your solar panel last? The role of 3rd party testing
Having a long warranty is a good thing, but that doesn’t make the product immune to failures. Having a broken panel and making a warranty claim can be a pain, so ideally your solar panels will just work. How can you know if they will?
One way to predict this is through independent testing. One lab that does this is PVEL with their accelerated testing of solar panels.
Accelerated testing means they take solar panels and subject them to harsh conditions to try to mimic what they would experience in the real world over decades of operation. The panels are heated, frozen, subjected to high humidity, and other types of abuse.
How did REC solar panels do in PVEL’s testing? They have been one of the best: for the past 5 years, REC panels have been graded as a top performer. This is a better result than many other top brands.
Doing well in this type of testing isn’t a guarantee that you won’t experience a product failure, but it does put the odds in your favor.
You can read a summary of their report for free here.
Features common to all REC solar panels
The use of different technologies is what separates the high end REC Alpha from the less expensive REC TwinPeak 3, but there are a few things that are common to all of REC’s current products.
Monocrystalline silicon
All current REC products use monocrystalline silicon cells. This type of silicon has higher efficiency - meaning that it converts more sunlight to electricity - than cheaper polycrystalline.
While traditionally more expensive, the market share of monocrystalline has been growing and is now used in a majority of home solar installations. This larger manufacturing volume means that the price advantage of lower-efficiency polycrystalline is smaller - or even non-existent - relative to what it was in the past.
Half-cut cells: better for shade
Half-cut cells are pretty much what they sound like: they’re solar cells that are cut in half. A typical home solar panel might have 60 individual solar cells, so one that uses half-cut cells would have 120.
How does cutting a solar cell in half make it better? These panels are wired with twice as many connections, making them perform better when part of the panel is covered in shade.
One possible disadvantage of this approach is that panels with half-cut cells have more wiring connections, which means more possible failures. However, with good manufacturing practices, panels with half-cut cells can be as durable as conventional panels. As shown by PVEL’s testing, that seems to be the case with REC panels.
REC product overview
Here are the key specifications of the panels discussed in this article:
| Alpha | N-Peak | TwinPeak 3 | |
|---|---|---|---|
| Efficiency | 21.7% | 19.8% | 20.3% |
| Power | 380 W | 330 W | 340 W |
| Thermal coefficient | -0.26%/°C | -0.35 %/°C | -0.34 %/°C |
| Power warranty | 92% | 86% | 80.7% |
REC Alpha Series: Best choice if you want maximum performance
The REC Alpha series is the highest performance panel in the REC product lineup, with power output up to 380 watts and 21.7% efficiency. This is a very high efficiency that places Alpha panels at the top of industry alongside products from LG and SunPower.
In addition to high efficiency, REC Alpha panels also have an outstanding power temperature coefficient - the best of any panel we’ve seen.
The REC Alpha has a 0.26%/°C power coefficient. This means that for every 1°C increase in temperature about 20°C, the panel will lose 0.26% efficiency. This is better than the SunPower X-Series, which has a power temperature coefficient of 0.29%/°C, and the LG NeON R with a 0.30%/°C coefficient.
The Alpha series comes with an excellent power warranty. It’s guaranteed to lose a maximum of 2% efficiency in the first year, and up to 0.25% each year after that, ending with a guaranteed 92% of its original efficiency after 25 years.
Heterojunction technology
To achieve its high efficiency, REC Alpha panels use heterojunction technology (HJT).
A panel with heterojunction technology has cells with multiple layers: a conventional monocrystalline silicon layer and additional thin-film silicon layers. The added layers allow a panel with HJT absorb more sunlight than monocrystalline silicon alone can.
HJT was pioneered and patented by Panasonic. The patent has expired, so a couple other companies have started incorporating the technology, including REC and SolarTech.
REC Alpha Pure Black Series
For home installations where aesthetics matters, like when the panels will be visible from the street, all-black solar panels can improve the appearance of your system by giving it a uniform black color.
Several manufacturers make all-black panels, including REC with their Alpha Pure Black. It’s the same technology as the standard Alpha but with a black backsheet. The dark color makes the panel operate a little hotter, resulting in a very slight loss of efficiency - about 5 watts per panel. That’s an insignificant loss for most people, and the improved appearance can be well worth it.
REC N-Peak: mid-tier performance
REC’s midrange panel is the N-Peak series. Like the other panels in their product lineup the N-Peak series uses half-cut cells, which you can tell by the distinctive line through the middle of the panel.
This product’s name alludes to the use of n-type monocrystalline cells. N-type solar cells use a different chemistry, replacing boron with phorphorus. This technical detail isn’t interesting to most people, but the end result is that n-type cells don’t suffer from a particular type of efficiency loss known as light-induced degradation (LID).
LID can result in a solar panel losing around 0.5% or more in efficiency within a week of going into service, so it’s a problem that manufacturers want to avoid. It’s a problem that plagues traditional p-type cells but newer n-type cells, like those used in the REC N-Peak, are immune to LID.
The N-Peak series reaches a maximum of 19.8% efficiency and 330 watts. The n-type cells help minimize efficiency loss over time: the N-Peak series is warrantied to achieve at least 86% of its original power output after 25 years.
REC TwinPeak 3 Mono and Mono Black: low cost, good performance
The entry level panel in the REC product lineup - which is still a higher performance panel than what many other manufacturers offer - is the TwinPeak 3 Mono. As the name suggests, it’s the third version of the product; you might find TwinPeak 2 panels offered at a discount price.
The TwinPeak 3 uses monocrystalline, half-cut PERC cells. PERC stands for Passivated Emitter Rear Cell, which is a mouthful that refers to the use of additional layers at the back of the solar cell that help it capture more sunlight. The panel manages to reach an excellent 20.3% efficiency and 340 watts.
That’s actually a higher efficiency than the N-Peak panel. You might conclude that it’s a better panel, but there’s an important caveat.
While PERC helps a panel achieve high efficiency, it’s susceptible to LID - the type of degradation that the n-type cells in the N-Peak are immune to.
This is reflected in the 25 year power warranty for the TwinPeak 3, which guarantees 80.7% performance after 25 years. That’s significantly less than the 86% guarantee with the N-Peak.
Still, the performance of the TwinPeak 3 is very good. It also has good thermal performance, with a temperature coefficient of -0.34%/°C.
REC TwinPeak 3 Mono Black
The TwinPeak 3 also comes in an all-black version, which will be appealing if your solar panels need to be installed where they might impact the curb appeal of your home.
The black version of the panel, like all dark-colored panels, suffers from a slight efficiency loss: 20.0% efficiency versus 20.3% in the standard TwinPeak 3.
Because of the visible wiring on the front of the panel, the TwinPeak 3 Mono Black is slightly less black than all-black panels from other manufacturers such as Solaria. However, unless you get quite close, the wiring won’t be very noticable.
Are REC solar panels a good choice?
While REC Group has less name recognition than SunPower and LG, it makes high efficiency solar panels that can often be found at a lower price than other premium brands. REC panels have also outperformed most other brands in 3rd party reliability testing.
If you happen to experience a panel failure, REC’s warranty covers labor so that you don’t have to foot the bill for a service call.
So, should you choose REC over other brands? I would say that they are definitely worth considering, but only if your installer is REC Certified and can qualify you for the REC ProTrust Warranty.
If the installer isn’t REC Certified, the product warranty will be 20 years instead of 25, and won’t include labor.
