Oct 27, 2009

Micro-inverters will make Solar Electric Home Power more practical

We recently took some continuing ed on solar electric. One of the neat things the professor focused on is the emergence of micro-inverters.
An inverter is a sophisticated electric switching box that converts DC current wavelengths to AC current wavelengths so solar, which is DC can power a conventional home which is AC.
The traditional method of inverting is to have the collective DC power from all solar panels funnel to one main inverter which then converts the collective amount of power from DC to AC. The micro-inverter as we see in the article below replaces the one main inverter with many smaller ones that are solar panel specific.

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...............

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.

Published on August 23, 2008 by Dan Hahn.

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