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Microinverters: A major advancement in solar energy technology

While it may appear as though Dave has fallen asleep recharging himself, he’s actually got a sexy new piece of solar equipment in his arms. The slim metal box is called an Enphase “micro-inverter”. No, a micro-inverter is not akin to a kickflip, ollie, or other skateboard trick.

If you’re just getting familiar with solar electric technology, you probably know at this point that there are two major components necessary to produce usable electricity from the sun. Simply slapping panels up on your roof and running wire down to your home won’t do a whole lot of good unless you plan on vaporizing your spouse.

To convert that direct current from the panels into usable electricity, what is required is a pretty bulky box called an inverter. So, you might imagine that a “micro-inverter” would simply be a smaller version of this box, right? Kinda like a “micro-chip” or a “micro-machine” or “micro-economics” (ugh)? The short answer is, “uh-huh”. In sum, this micro-technology is a hell of a lot better for many reasons. To understand why though, let’s get a little more familiar with “regular” inverters and how they work with solar panels.

Pretend for a minute or two that you are newly named foreman of a very unique Peruvian diamond mine. Diamonds from this mine sparkle with a luminescence unlike any other diamonds. However, to create these special gems, the raw diamond material must be polished minutes after it is extracted from the earth to attain this luster.

The previous foreman (let’s call him Hector), only trusted one person (let’s call him Jose) to polish the rough unfinished diamonds into highly desirable, glittery diamonds. Of note, Jose has recently called off work with illness more than usual, is nearing retirement age, and you sense he’s becoming a little disgruntled. The rest of Hector’s miners (Juan, Domingo, and Maria) extract raw diamond material from the mine but are highly interdependent on one another to get their rough diamonds to Jose before they lose their ability to be special and glittery. Meaning, if Domingo decides to take a break, Juan and Maria have to stop what they are doing to wait for him to get back to work before they can pass more diamond material along the line for Jose to polish.

Consequently, a lot of valuable diamond material gets wasted. Hector was fired because the daily yields from his mines were, well… lackluster. To alleviate this problem and get more special sparkly diamonds out of the mine, what do you do? Hold that thought.

In a conventional solar power system, interdependent strings of panels are placed on roofs and operate in much the same fashion as Hector’s miners. Panel A, Panel B, and Panel C are a lot like Juan, Domingo, and Maria. If one panel gets obstructed even by just a little bit by a big leaf, bird poop, or lovely tree shade, the entire string of solar panels suffers, sending significantly less or even no raw power down the line.

Each panel needs to work with other panels in the string to get raw power to the inverter. The regular inverter is a lot like Jose, taking the direct, rough, unfinished current from the combined panels and converting it into sparkly, glittery alternating current you can use in your home. So, when shading or obstructions impact one of the panels (a lot like Juan, Domingo, or Maria taking a breather), the inverter (Jose) has a lot less raw material or current to work with. Let’s go back to the mine.

What if you placed small robots alongside Juan, Domingo, and Maria to monitor their performance and carefully polish raw diamond material into finished diamonds? Then, even if Domingo is unable to find any raw diamond material to extract, Maria can still be extracting, polishing, and producing.

In addition to teaching your employees new skills (which by the way has been related to lower turnover), you are now a lot less reliant on a disgruntled employee (Jose), you can increase your diamond harvest, and you are able to eliminate a point of failure along your production line. Your only concern is that your workers get along well with their new micromanaging robot companions.

This is precisely the reasoning which led Enphase Energy engineers to create micro-inverters. Micro-inverters are attached to every single solar panel in the system and each one is capable of converting direct current from its solar panel into usable electricity – independent of other panels on the string. This means that even if one panel gets shaded a little bit by dust, bird poop, or a tree, the other panels are still capable of feeding usable electricity into your home or business.

Moreover, you are no longer reliant on the regular inverter, a bulky eyesore of a box that has a lifespan of 10-20 years. Currently, if you have a massive solar installation on your commercial plant, when your inverter fails, you need to purchase all of your electricity from the grid until it gets replaced. That can represent a sizable chunk of unplanned cash out of pocket.

In addition to more uptime, micro-inverters allow system owners to monitor the energy output of each individual panel, alerting them if one is underperforming (Each micro-inverter can send a signal through your internet connection so that you can see how well each one is doing).

What’s more, you can now combine different types of panels together and place them at different orientations to the sun and still expect good production out of them – unheard of before. 

Finally, micro-inverters allow your solar system to be scalable – meaning you can purchase a few panels to start out with, then add onto your system without additional engineering outlays. Lab tests indicate these micro-inverters will have a lifespan of about 120 years.

Last modified: December 10, 2018

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Dave Merrill, 20-year installerCF PoetStandtall6Dan Hahn Recent comment authors
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Anonymous

your pop ups are extremely annoying

Dave Merrill, 20-year installer
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Dave Merrill, 20-year installer

I hope that the 8 – 9 years since this Enphase “sales job” was written – that people has seen through the hype and fad of microinverters, Their high failure rates because of the natural laws of physics (heat, circuit board fatigue and excessive complexity) have passed judgement beyond the marketing spin of Enphase and their disillusioned fan base. It has always been plain and simple – don’t put solar modules in shaded areas, and don’t put 450+ electronic parts per box up on a hot roof. It’s like standing a bunch of pencils up on their erasers and hoping… Read more »

CF Poet
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CF Poet

Man,great site really. However, I think Emiliano Jordan has a good point. A year and no page edit? Also, Mark has some good points; 1.”they are installed in the worst possible area being on the roof behind the modules.”

Standtall6
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Standtall6

Micro-Inverters really are not a new technology. In the mid 90’s Micro inverters were all the craze. “PV’s solution.” Problems arose when every one of the micro-inverters failed with in two years. Needless to say the business creating them also failed. The inverters are truly the work horse of the a PV system. When you put them in extreme weather conditions they are sure to suffer. Now because of great marketing and some improved technology by enphase specifically, Micro-inverters are back on the scene. Great article in Photon Magazine November 2009 talks in more detail about history of Micro-inverters.

Ken
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Ken

I am looking for microinverter, other than Enphase, which model or brand name you would recommend me to find out more about it?

Mark
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Mark

Inverters have always been the weakest link in the system. In terms of reliability, operating temperatures and temperature cycling play major roles to life. With these micro inverters, they are installed in the worst possible area being on the roof behind the modules. I do like the idea of the micro inverters as the scalability is ideal but can’t support them until they have a chance to prove the reliability. More Points: 1: They have only been on the market for a little more than a year- no track record in the field. 2: The potential for 1 problem (… Read more »

Keith
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Keith

I’m building my own solar panels, will your micro inverters work with any panels or do I have to make a specific watt panel, can they be used with a battery storage bank for when there is no sunlight?

Dan Hahn
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Dan Hahn

Hi Patrick,

Good question. For large installations, it could be sensible to include a mix of conventional string inverters as well as microinverters to bring the cost down. If you own a business and are considering this, give me a buzz.

Patrick
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Patrick

How does the cost compare to traditional inverters? Obviously on an individual basis they would be cheaper. Is there a point where an installation gets large enough that the traditional inverter is the cheaper way to go? Not debating value at the moment, just upfront cost.

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