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The Benefit of Rooftop Micro-Inverters

Wednesday, July 7, 2010

For years the tried and true method to process solar energy has been the centralized inverter unit. But with time, technology advances creating new products that often improve our lives in many ways. This is the case with rooftop micro-inverters, which are only a few years on the market.

 

Like many advancements, there is a lot of misinformation with new equipment that can make opting for micro-inverters seem like a risk. In reality, micro-inverters are a rethinking of solar energy processing. Their advanced design enables them to work under extreme conditions, and they are proving to be as reliable as the traditional centralized units.

 

The main difference between the Enphase inverter and other inverters is the small size. Along with its relatively lower cost, the Enphase Micro-Inverter is designed to be installed individually to a single photovoltaic module. This configuration means that the inverters are connected to the system in parallel rather than in series, so if one module is not producing at peak efficiency, it will not affect the overall performance of the system.

 

One of the biggest drawbacks of the traditional centralized unit is the large thermal footprint. Because the units often process large quantities of power — upwards of 3,000 unified watts — they create a tremendous amount of waste heat and if not mounted in a cool location they can overheat and fail. This design also requires live DC energy flowing through your house any time power is being generated.

 

With rooftop micro-inverters, like the Enphase microinverters used by Sunetric, the amount each unit is processing is only a fraction of a centralized unit. Processing lower DC input voltages allows for greater integration of semiconductors, which reduces the number of components in each unit. This makes each unit smaller and stable in rooftop environments. Best of all DC energy becomes AC energy on the roof, so you now have total control over the live energy in your home.

 

The design and construction of the Enphase units makes overheating a non-issue, even in the extreme temperatures on Hawaiian roofs. Each unit is housed in a NEMA 6 rated “potted” design that surrounds the micro-inverter in an encapsulating compound. This compound helps to dissipate the heat generated by processing solar power and protects the micro-inverter from the elements. In addition, the heat generated under your PV panels naturally rises to the roof’s ridgeline, creating a passive cooling method for every inverter in the system.

 

The Nema 6 rated housing also makes the micro-inverters better suited for exposure to the elements on Hawaiian roofs. Classic centralized inverters are NEMA 3R rated and only water-protected. The modern Enphase units are waterproof from the top down to prevent damage not just from water but also dust, external air and insects. Centralized units cannot offer that protection.

 

We understand the tendency to compare the long-term durability of traditional centralized inverters to micro-inverters:  micro-inverters are a new technology and as a solar customer you want to be sure they will be reliable. Both centralized inverters and micro-inverters have a failure rate of roughly 0.005%. In the case of a malfunction with a micro-inverter, however, Enphase is not only quick to respond with replacement parts at their cost, they also offer to pay for the power lost to the customer. A centralized unit is much larger, which increases the freight costs and delivery time when repairs are needed.

 

It’s true – rooftop micro-inverters are new and may seem contrary to what you know of solar energy converters right now. But technology has changed the way we now look at converting solar into usable energy. Ignoring this is like stepping back ten years, looking at the MP3 player and thinking “40,000 songs in my pocket? That’s ridiculous.”

 

You can now have safe, reliable energy created right on your roof. And you’ll have the assurance of Enphase with each unit, no matter how hot it gets up there.

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