Reliability means that the home energy solution will never completely break down. There are 2 types of home energy solutions — one that can break down completely and one that can’t. Solutions that can break down completely incur hidden costs that affect the overall cost. What monetary value can be put on a solution that can never completely break down versus one that can?
The solution that can break down completely is called an “optimized-string”. It consists of a series of solar panels and a single component called a central string inverter; it may also include devices called optimizers, one for each solar panel. When the central string inverter fails, the entire solution fails, and the customer has a crisis on their hands which may include finding a technician, getting the right part, part availability, expedited shipping, DOA’s, energy-production loss, and unexpected utility energy costs.
The solution that can never completely break down uses “microinverters", and Enphase Energy has been the leader in this arena for over a decade. A home energy solution based on microinverters doesn’t need a central string inverter, for each solar panel has its own “micro” inverter. With this type of redundancy, the microinverter-based solution is more reliable than an optimized-string because even if a microinverter does fail, the solution will continue to work and produce energy. This kind of reliability is not possible with an optimized-string solution.
Both AC and DC electricity are safe if installed correctly, but the fact remains that the electrical devices in our home require AC electricity to operate; why is that? In simple terms, when there is an electrical hazard, it’s much easier to break an Alternating Current of electricity than it is to break a continuous Direct Current. AC electricity is much safer when considering an application with a lengthy lifespan, especially outdoors in the elements. Ask any fireman who has had to deal with hazards known as arc faults, or consider why a fire station chose a microinverter-based energy solution on their station, and this will definitely help sway the purchasing decision.
The optimized-string is a high-voltage, DC-based solution whereas the microinverter is a low-voltage, AC-based one. High-voltage DC wears down components over time and this is why the warranty on a central string inverter is ~10-years compared to a microinverter’s 25-year warranty. High-voltage DC over time presents a potential danger to the customer, and definitely not one which is discussed at the point of sale for an “optimized-string” solution. Electrical components wear down from usage, contacts loosen, and weather-related conditions cause degradation enabling potential electrical hazards.
Furthermore, the optimized-string with its central string inverter, requires a combination of high-voltage to operate; all of the solar panels must be working or at least meet the minimum voltage requirement — 8 panels is usually the minimum. With low-voltage microinverters, there’s no minimum panel count, and this makes the microinverter technology stringvoltage agnostic and more flexible than an optimized-string solution.
Residential customers who buy a home energy solution want to make sure energy production is constant with no downtime or hidden costs. Utility-scale solar involves big company purchases on fixed budgets, also with the same expectations. Product longevity is a crucial element of the purchase. With the 2 competing energy solutions aforementioned, which one lives the longest?
The answer is — the microinverter. The microinverter has never had any moving parts which can break down, and even though some of the newer central string inverters do not have any moving parts, the microinverter still wins because of its redundancy. Most central string inverters contain moving parts such as cooling fans, which will break down. The longevity of a solution must be measured for the amount of time it performs continuously without failing, and that is where the microinverter trumps the optimized-string. An optimized-string may last as long as a microinverter-based solution with complete failures from time to time, but those failures and downtime in between must be considered.
Microinverters are completely sealed off from the outside elements, which ensures their longevity. Most competing central string inverters require cooling fans with vents which access the outside elements — aka “active cooling”; this only contributes to the shorter lifespan of the product.
Furthermore, a phenomena called potential induced degradation (PID) was discovered in 2010 involving solar panels constantly operating under high-voltage conditions in utility-scale solar. Microinverter-based solutions are low-voltage-based, so they are immune from PID. High-voltage-based optimized-strings can be made PID-immune, but that requires additional hardware which is a hidden cost.
With over a decade of R&D investment, Enphase has advanced and optimized its microinverter technology to where it is now offering its seventh major generation of product — called IQ7. The Enphase microinverter is such a mature product that the company dominates the microinverter market.
Cost was not mentioned as a key attribute for selecting a home energy solution because it is truly a moot issue. There are many costs to consider: 1) initial hardware-installation costs, 2) balance of system costs (BOS), and 3) operations & maintenance (O&M) costs over the life of the solution. The overall cost difference between an optimized-string and a microinverterbased solution is minuscule, and Reliability, Safety and Longevity are the real cruxes.
In summary, buying a home energy solution has never been easier and cheaper to do; the technology has matured greatly. As an Enphase home energy solution owner who has been involved in the solar industry since 2010, Enphase’s solution is superior to the centralized, single-point-of-failure optimized-strings. Microinverters offer true reliability, safety and longevity to the customer which an optimized-string cannot match. Enphase in my opinion is truly the Apple of the solar world.