March 30, 2020

AC Modules are the Future of Solar


The AC module, ACM or AC solar panel is the optimization of solar on the rooftop. The concept of AC modules originates back with NASA in the 1980s; the patents for the technology were acquired by Sanyo, a subsidiary of Panasonic in the 1990s and acquired yet again by Enphase in 2014. The AC module combines three separate parts into a single product — solar panel, microinverter and accompanying cable for connecting to the rest of the solar system. After being commercially released in 2017, Enphase Energized® AC Modules have now matured as a product and are rapidly gaining in popularity and use in the solar industry.


Enphase Energized® AC Modules are Safer and Simpler

AC modules have built-in rapid-shutdown capability, guaranteeing NEC 2014 compliance. For optimized-string systems to be NEC 2014-compliant, many require not only solar panels, power optimizers, and central string inverters, but also the addition of a rapid-shutdown kit in order to meet compliance. Therefore, in comparison, the AC Module is a much simpler product.

  • AC modules use low-voltage AC and eliminate the risk of fire hazards caused by DC arc faults. 
  • Low-voltage AC solutions are PID-free unlike high-voltage DC systems operating at 600-1,500 Volts which are prone to this degradation.

AC modules offer a higher level of safety over optimized-string systems that utilize high-voltage DC electricity. With AC modules, it is 240 Volts AC coming off the roof, not high-voltage DC like the optimized-string systems present in ranges of 600 to 1,500 Volts. This difference between AC and DC electricity can actually protect a homeowner from a catastrophe like the Walmart fires which were caused by high-voltage DC solar systems. Besides the safety offered by AC Modules, the technology is simpler to install, and because it is AC electricity, a local electrician can do the job. Simplicity wins over complexity, and AC panels are the best choice for residential and low-end C/I solar PV systems. It is important to note that as module wattages increase, the $/Watt value of the Enphase Energized® AC Module also increases in a linear fashion. The power generated by 24 panels from just a decade ago, can now be matched by about 14 panels today; that’s a 40% improvement in technology right there and gives the AC module in residential and low-end C/I solar even more flexibility and value since a smaller form-factor is now possible on the rooftop.

The AC modules offer the most reliable solar system configuration currently available on the market, for their design topology has no single-point-of-failure; if an AC module does fail, the other AC modules will continue to operate. Competing systems using central string inverters are inferior since they can completely fail.

Enphase has enjoyed much success with its AC modules since their debut in 2017. Solar panel companies like Emmvee, Jinko Solar, LG, LONGi, Panasonic, SolarWorld, Solaria and SunPower have all partnered with Enphase to produce an AC module product. Just to spotlight the growth of the product, companies such as SunPower have now converted 95% of their residential product portfolio to AC modules from the old way of using a separate solar panel and MLPE (Module-Level Power Electronics) component. LG had phenomenal success with its AC module which sported an integrated IQ™ microinverter, selling over 100,000 of them. Solaria has doubled its production capacity and is now on its second major generation of AC module which has been a very successful product. Solar distributor Renvu has sold out of earlier models and is now selling the PowerXT® 365-Watt AC Module. Panasonic has also seen much success with their Enphase Energized® AC Modules, and has introduced an additional triple-guard warranty for their AC modules; this has leveraged IQ 7X™ microinverter quality and reliability, allowing Panasonic to rapidly gain marketshare with their flagship HIT® N-series modules and other award-winning products. The Enphase online store currently is selling LONGi and Solaria AC modules.

Below is a table showing AC modules offered by some of Enphase’s solar panel partners; more models and partners are expected later this year; the addition of LONGi’s AC module, sporting an integrated low-end IQ7 microinverter, is the latest arrival.

  Panasonic Solaria SunPower LONGi
Model  N330E-HIT Power XT 365 R E- and X-series LR6-60PB
# Cells 96 60 96 60
Wattage 330 365 327-360 295-315
Efficiency % 19.7 20 21-22.2 18.7
Warranty(Years)  25 25 25 10/25
Available Now Yes  Yes  Yes  Yes

The following installation video shows the simplicity of installing Enphase Energized® AC Modules. 

Enphase now has over 700 professional installers using the Enphase Energized® AC Modules.  Long-Tail installer, Damon Egglefield, of Mirasol Solar in Florida is installing SunPower X22 series Maxeon 5’s with integrated Enphase IQ 7AS™ microinverter.  Damon says “AC modules are the better way to go in that they simplify installations due to several, less-needed steps, offering much better logistics since the inverter is not a separate product to account for in inventory.  Compared to the Solarbridge Pantheon microinverters bolted onto the solar panel that SunPower was using, the detachable Enphase microinverter simplifies any potential service issues, as well as provides better cooling for the components”.

In reality, the AC versus DC battle was won long ago when it was proven that AC was safer than DC and could travel much longer distances over wires than DC could. On his deathbed, Thomas Edison, the father of DC electricity, stated that “one of his greatest regrets in life was not paying Tesla more respect, nor fully appreciating Tesla’s work ” — of course, he was referring to Nikola Tesla, the father of AC electricity.  In terms of safety, reliability, and longevity, AC-coupled solar is superior to its DC-coupled competition. The growing consortium of AC module providers in the marketplace is a sign that a shift is occurring towards this better technology, so AC modules are clearly the future for rooftop solar. If you consider that most homes have AC appliances and devices throughout, then AC panels on roof make common sense. 

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