For the customer looking to go solar, it is a daunting task considering all the terminology, components and vendors to choose from. Obtaining more than a single quote is recommended, but it’s most important to understand the various types of solar solutions currently offered in the marketplace before you buy. Choosing the right solar solution can be the difference between true peace of mind versus having to deal with a crisis at some point in the future.
Let’s start with a brief history of solar photovoltaics (PV) from the early 1980s, and lead up to where solar is today, almost four decades later.
In 1981, SMA Solar Technology released the first residential "central string inverter" product which made it possible for people to have solar PV systems installed on their homes and connect to their home’s electrical wiring. Basically, a string of solar panels would be daisy-chained together with each solar panel connecting to the one next to it, and then the final panel would be connected to the first panel creating what installers called a “home run”; then, this string of panels would be connected to a "central string inverter" so the electricity generated by all the panels could be converted to AC electricity for use in the home’s electrical grid.
For almost three decades, this solar PV configuration was the de facto standard, but it was plagued by reliability and safety issues — 1) if a single solar panel had a performance issue, then the performance of all the panels would be reduced to the performance of this weakest panel, 2) if the "central string inverter" which converted the electricity generated by the solar panels became inoperable, then the entire solar system would be inoperable, and 3) because the solar solution combined the DC electrical output of all the solar panels and converted it to AC using the "central string inverter", the chances of a DC arc fault, fire hazard increased dramatically as the system aged. Sad to say, but reliability issues became synonymous with solar PV systems and stigmatized the industry.
So, like with any new technology, better solutions were devised to alleviate the aforementioned issues, and in 2008, Enphase Energy was able to successfully commercialize a more reliable solar technology with the release of a device called the "microinverter”; these devices where placed under each solar panel and changed the power topology of the solar system from a “centralized” to a “decentralized” one; they enabled each solar panel to generate their own AC electricity independent of the other panels; this independence meant the microinverter-based system had no single point-of-failure component as systems with a "central string inverter" had. This reliability issue which had stigmatized solar PV systems for quite some time had been resolved by Enphase, and furthermore, because the DC-to-AC power conversion performed by the microinverter was done on a per-panel basis and not by a "central string inverter", the DC arc-fault issue was resolved, giving the customer a truly “safe AC” solution. Also, symptoms involving Potential-induced degradation which were common in high-voltage solutions using a "central string inverter”, were made impossible by the use of microinverters which used low-voltage.
With the microinverter, the venerable "central string inverter" looked like it could become obsolete in residential solar, but in 2009, just a year after the debut of microinverters, another type of device was commercialized which was lower-costing and gave the "central string inverter" system a quasi-form of reliability and improved performance; that device was called the DC power optimizer; the optimizer resolved the reliability issue which "central string inverter" systems had such that an inoperable or poorly performing solar panel would no longer affect the rest of the panels in the system; however, it did not resolve the fact that the failure of the "central string inverter" would still render the entire system inoperable. The new solution using DC power optimizers with a "central string inverter" was called an “optimized-string” solution. Although inferior to the microinverter-based solution, at that point in time, the “optimized-string” was an up-front, lower-costing solution, so it did gain acceptance in the installer community. Still, if up-front and operations & maintenance (O&M) costs over a 25-year period were considered, the true cost difference between the two solutions would be negligible.
In 2013, I started building my home’s solar system, and now have 6 separate strings of solar panels with a total of 85 Enphase microinverters. I have yet to have a single microinverter fail, and even when one does fail, it will not be that big an issue; the other ~99% of my solar system will continue to operate, and the problem can be addressed at my leisure. For customers who buy into an “optimized-string” solar solution, when their central string inverter fails, they have a crisis on their hands with their entire solar system inoperable — can they find the original installer, is there part availability, what is the service cost, will the replacement be dead on arrival, when will the system be back up and running, et cetera? Doesn’t it make better sense to purchase the solution which will never cause a crisis situation? This is truly what an Enphase microinverter-based solution has meant for me for the past 7 years.
In summary, I believe Enphase’s microinverter solution to be the safest and most reliable solar solution on the planet, and I highly recommend it if you want a simple solution that will not cause you future service repair headaches. In reality, what price can you truly put on “peace of mind”! Choose Enphase, and you’ll be happy you did!