Microinverters vs. Central Inverters

So you’re installing a brand new solar system.  Do you go with microinverters or stick with a central inverter?

What’s the function of an inverter?
The task of an inverter is to convert direct current (DC) to alternating current (AC), which is needed for the vast majority of electrical devices.   Solar energy comes in the form of direct current, which must be converted to AC for this reason.
Central Inverter
Traditionally, central inverters have been used in solar systems to convert DC to AC.  One central inverter is connected to multiple solar panels.
Central inverters are trusted by many because they have been around for so many years and people are familiar with them.  This technology has been around longer, so the collective amount of real-world use gives central inverters a certain kind of credibility in the industry.

SMA SB 3000US Sunny Boy Grid Tie Inverter 3250W with DC disconnect

The key benefit of a central inverter is cost.  The bottom line is that central inverters currently cost less per watt than microinverters.  This is why many home owners and most utility scale industrial applications opt for central inverters.  A good number of people argue that having a single conversion point simplifies grid management for such large applications.

Critics of central inverters point out that high voltage levels are centralized with these inverters and thus pose a safety hazard.
The main disadvantage of having a central inverter is that your system is “only as strong as its weakest link.”  If one panel is subject to shading or some other form of coverage, the energy output of your array can be decreased by fifty percent.  This setback has created an opportunity for microinverters to make their way into the market.
Microinverters convert the DC electricity from each panel to AC electricity.  They attach behind individual solar panels in the array, allowing each module to operate independently.  Microinverters can maximize the power produced by each panel, rather optimizing for the “weakest link” in an array.  Because of this, microinverters are particularly advantageous for systems in locations that might have shading or some form of coverage (i.e. dirt, snow, etc).
Using microinverters definitely has its advantages, predominantly for residential applications.  Microinverters, such as the Enphase M215 on the right, are desirable for DIY applications because they’re so easily installed.  Microinverters are easily scalable, meaning you can add to your existing system with little trouble.  Microinverters also allow for module level monitoring and comprehensive analytics, making it possible for you to view how much energy is being produced by each panel.  For these reasons, microinverters have become increasingly popular for residential applications, particularly in California.
The main disadvantage of microinverters is the price tag; they still cost more per watt than central inverters.  Dual microinverters have been introduced to address this issue.  Because dual microinverters connect with two panels at once, the cost per watt is cheaper than single microinverters.

Currently, Enphase Energy dominates the market for microinverters.  Enphase offers a fifteen year warranty on their microinverters.  Over the last several years, Enphase microinverters have made a remarkable breakthrough in the solar market.  Many believe that microinverter technology will continue to gain traction in the years to come.

What do you think?

As microinverters (and dual microinverters) become cheaper, what can we expect to see?  If microinverters become cheaper than central inverters, will central inverters eventually become obsolete?  Perhaps there will continue to be a place for both technologies, each with their respective applications.  I guess we’ll just have to wait and see!

Original Article on Go Green Solar


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