All you need to know about AC solar modules
There’s a growing market for plug and play solar deployment options and that’s where AC solar modules come in. Let’s take a closer look at AC solar modules and how they’re meeting the demand.
The market of the so-called plug and play solar modules is growing faster than expected. Such deployment is mainly related to the growth of Enphase as the most important brand in the microinverter market, but it’s also due to the relevant partnership that Enphase has been working on with important solar module manufacturers to develop an integrated product of AC modules (ACM) approved and pre-assembled by the recognised leaders.
The technology is relatively new and many are not quite clear about what it means or what the benefits are of choosing an ACM. In 2014 the market share was close to 73 MW worldwide, but now the expected capacity installed could achieve 1 GW by 2020, which is close to 13 times more than in 2014.
Here we will discuss these aspects.
Why choose ACM instead of DC modules?
This is the first question that may arise if you’re interested in ACM and is in fact, the most important one.
In order to answer that we must first refer to the definition of the AC modules from the National Electrical Code 2017 (NEC) of the United States: “A complete, environmentally protected unit consisting of solar cells, optics, inverter, and other components, exclusive tracker, designed to generate AC power when exposed to sunlight”.
In the definition we must highlight the most important word of the phrase: inverter.
AC modules are often referred to as normal DC modules which have a pre-assembled connection to a microinverter on the rear side of the panel, a combination that has been tested to work on accurate performance.
In other words, the benefits attached to the ACM are mainly related to the benefits of using a microinverter system: increased reliability, eliminated mismatch losses, easier expansion, increased security and more.
To learn more about benefits of choosing a microinverter topology instead of a conventional system read What to Expect From The New Enphase IQ 8 Microinverter.
An additional benefit of choosing ACM is that the installation process is much faster than the traditional DC system topologies and it is even faster than a conventional microinverter system design, as the installer does not need to place and make the connections between the modules and the microinverter one by one.
The integration also means fewer components to stock, transport, carry and install; features that are highly appreciated by most solar installers.
AC module vs DC module coupled with a microinverter
You might be thinking that it is the same to choose a DC module and wire it to a microinverter (which is not hard at all) as purchasing an ACM which is just the pre-assembled connection.
So is it just a marketing strategy? Well, not exactly.
There are typical misconceptions in this matter and it’s not often easy to know whether you are installing a true AC module or just a DC module with a microinverter attached.
The big difference lies in certification.
The AC modules must be listed for the application under the acknowledgement of recognised testing laboratories worldwide like Underwriters Laboratories (UL).
Particularly for this laboratory, a real AC module will require certification of two principal UL standards, the UL1741 and the UL1703. These standards are referred to as the requirements of the combination between the panel itself and the microinverter, while at the same time establishing the performance of the AC module according to the mounting arrangement of the microinverter on the module.
These standards are in accordance with environmental tests as well.
Moreover, the AC cables are tested as part of the whole system. They cannot deform or be damaged when under complete immersion in water, or in the face of high or low temperatures and the presence of ultraviolet rays.
Only when the AC module is listed as such, can the requirements for DC modules according to fault detection and interruption, DC cable management, DC grounding, AC grounding conductor to the inverter and DC disconnecting, be completely ignored by the solar installers.
This makes life easier for solar installers and costs may be cheaper for the homeowners.
In order to find out if the panel that you have installed is a listed AC module, look for the AC ratings which should be on the nameplate of the panel with the corresponding laboratory test certification (UL 1741, for example).
One of the minor downsides of installing a DC module with a microinverter attached on the back is that the warranty of the panel could be void if the combination is not adequate. With an AC module you completely avoid this issue.
Top ACM partnership with the top microinverter company
Based on the above reasons, one of the largest and probably most important microinverter company in the world Enphase Energy, has developed important alliances with some of the top solar module manufacturers.
One of the first brands in this alliance with Enphase Energy was JinkoSolar.
The model was released in 2017 and named as the Eagle AC 60 Plug & Play AC Module.
This model was adapted to work with the Enphase IQ 6 and IQ 6+ technology and was especially designed to work with AC module applications, all of them compatible with Enphase IQ Envoy, Enphase IQ AC Battery, the Enphase Enlighten monitoring and analysis software, and the Enphase Q Cable.
The module works with rail-less or traditional racking systems, has class II double insulated enclosure and is of course, listed under UL certification.
The Eagle AC 60 is a completely black monocrystalline silicon module and has a very elegant appearance.
Important Note: Super black solar panels aren’t ideal for Australia. Learn here why there are better alternatives for our climate: All You Need To Know About Super Black Solar Panels.
The warranty of the total system is backed by JinkoSolar including the module itself, the microinverter and the web-based module-level monitoring.
Moreover, the performance of the module across the 25 years of the product is guaranteed to be at 80%. as most DC modules are.
Regarding some of its AC ratings, the maximum continuous output power is 230 VA with a nominal voltage of 240 V, a nominal output current of 0.96 A and an efficiency of 97%.
DC properties are also provided in a range from 280 – 300 Wp.
LG was also one of the first companies to certify the AC module technology with Enphase.
As JinkoSolar, it was released on 2017 and consists of a 60 cell monocrystalline AC module integrated with the IQ 6+ technology.
The name that the company provided to the module is the LG NeON 2 ACe.
The appearance of the module is black and it hash a certified 15 mm distance between the DC module and the microinverter that mitigates any impact in the performance and reliability of the module. This allows a sufficient air flow in the rear side between the module and the microinverter to cool the panel under the highest temperature conditions.
The AC module is also listed under UL1741 and UL1703.
Regarding guarantees, the microinverter has a 25 year warranty and the AC power output is expected to be at 84.8% by the end of that period.
Waaree is one of the leading solar module manufacturers in India, which is why Enphase also made an alliance with them to support AC modules to the Indian PV market. An alliance that will surely benefit Enphase a lot when they release the new IQ 8 system in 2019.
The partnership was announced in 2017 and in fact, a 1 MW rooftop project in India has already been installed with this technology.
The microinverter was especially designed with an IP67 protection that allows it to endure the harsh Indian climate with elevated temperatures and an elevated presence of dust.
The WSM-335 AC (72 Cells) module from Waaree is a good example of an AC module that is not only listed under UL tests, but also under the Clean Energy Council, IEC and ISO standards, particularly selected for the environment in which this AC module will perform.
It is certified to withstand corrosion, dust and sand.
Moreover, the warranty of the module is for 25 years with a minimum of 80% output, while the microinverter holds a 10 year warranty (substantially lower than LG).
The technology used is monocrystalline and is a 72 cell module with a maximum continuous AC output power of 250 W and a nominal voltage of 230 V.
The Solaria PowerXT-AC module is the first AC module that works with the Enphase IQ 7+ technology with a really elegant appearance which adds value to the aesthetics of the module.
The module has a 20% efficiency and perhaps has the second highest AC module power output in the residential market.
The module complies with all the rapid shutdown requirements from the US and has a smart-grid technology that complies with advanced grid, voltage and frequency support incorporated.
The American company developed this AC module in partnership with Enphase to achieve a maximum continuous AC power of 290 VA with a nominal voltage of 240 V and a 25 year product warranty.
The company offers three models: The 350R-AC, the 355R-AC and the 360R-AC, all of them with different DC ratings.
The main difference between the AC module technology from Enphase with the IQ 6 and the IQ 7+ is mainly related to the maximum AC power output that can be obtained from the module, along with the monitoring components that must be coupled with the solution.
This case is a perfect example of the misunderstanding around the concept of AC modules.
Many solar folks are amazed at the new AC module HIT N330-N325 released by the remarkable Japanese company, Panasonic.
Panasonic has opted for a unique heterojunction technology that uses ultra-thin amorphous silicon layers that provide high energy output and offers the leading temperature coefficient of the industry with -0.258%/°C (the lower the coefficient, the better) with one of the highest efficiency values of the industry (19.7%).
Moreover, the technology has an extremely low Light Induced Degradation (LID) associated with losses in the first year of operation, and a zero Potential Induced Degradation (PID) associated with losses due to leakage currents and failure in insulation, which are highly valuable and unique features of this module.
Besides, the product has a 25 year warranty and it’s also a bifacial module designed to achieve higher power output by using the reflected sunlight.
And if that’s not enough, the Panasonic module also has 4 bypass diodes. These elements are used to eliminate the risk of hot-spot phenomena under shaded conditions. Most modules have only 3 bypass diodes.
There is no doubt that the Panasonic HIT module is a jewel of the PV industry with the finest PV module technology, however, the term AC module does not fit our definition.
The module does not come pre-assembled with an Enphase microinverter and is not listed as such, either.
The truth behind it is that Enphase only announced that the panel would be “compatible” with the IQ 7X microinverter, which is designed to fit 96 cell modules, as this one is.
The advantage of this announcement lies in the fact that Enphase approves a microinverter system connected with the IQ 7X and the HIT modules from Panasonic, although not as an AC module, but as a typical microinverter configuration.
Still, the announcement of mutual cooperation between Enphase and Panasonic to produce ACM is promising news as we could see a true AC module product from these companies very soon.
Enphase is one of the leading companies in the microinverter industry and as such, their objective is to promote an easier and faster installation product to achieve a higher number of installations.
To achieve such a goal they manufacture the AC modules through partnerships with top brands in the solar industry.
Four leading companies already offer this solution integrated with IQ 6 and IQ 7+ technologies: JinkoSolar, LG, Waaree and Solaria.
The features of these modules are different, although the power output and module technology are similar.
The biggest benefits of the AC module are the certified performance of the system and the speed-up process of the PV array installation under the microinverter concept.
Solar black panels are not recommended for the Australian climate.
You might be surprised, but solar panels don’t enjoy getting hot. In fact, heat can reduce output efficiency by 10-25%. There are better alternatives such as mono or polycrystalline modules, which have the highest efficiency and also the highest temperature coefficient at Pmax.
The balance between installation cost differences and the price of an AC module will also determine whether choosing an ACM is a viable option.
Talk to your solar installer to get the best solution for your property.
Finally, it is important to notice that the market share of ACM is expected to reach at least the 1 GW target by 2020.
The leadership of Enphase will be a decisive factor in determining if such forecast can be achieved or not.
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