Inverters, Microinverters, and Optimizers. Whats the difference?

There is a lot of information out there about all the different ways used to get the energy from solar panels to your home.  Are optimizers, string inverters, or microinverters best?

Shading Effects

graphic of traditional versus SolarEdge inverters tshowing the superior efficiency of the SolarEdge Inverter

 

The diagram to the left illustrates how shading affects a solar system with a string inverter, when compared with an optimizer (or microinverter) set up.

String inverters have the panels connected to one another in series.  Think of this set up as a string of Christmas lights.  When one light goes out, they all go out.  For solar panels, this means that the production level of the string of panels can only be as high as the lowest producer.

Optimizers make the solar panels produce independently of one another.  This key difference means that temporary shading on one panel from a tree or chimney does not affect the production of the neighboring panels.

 

Inverter Types

 

String Inverters: String inverters change the DC current produced by the solar panels to the usable AC current that is transmitted by the utility grid to your home. These inverters are limited by design for the reasons mentioned above- if there is any situation where the system will be shaded for even a portion of the day, a string inverter is not as optimal as an optimizer.

Additionally, remote monitoring of a string inverter system is an additional system that needs to be implemented.  The cost of which is not justifiable when compared to the production advantages and inclusive monitoring of an optimizer system.

Microinverters: A microinverter system employs small inverters on the backs of each individual panel.  Enphase is the most popular microinverter system on the market, and it allows for the homeowner to avoid shading issues that would otherwise hamper the production of a string inverted system.

While microinverters offer a 25 year warranty and increased production with monitoring, they are not as optimal as a DC optimizer system.  Electronic components perform best when they are at a cool temperature.  This is why your computer has fans, and electric motors have heat syncs. By placing a microinverter behind each solar panel, the capacitors which are performing the DC to AC conversion are likewise being placed at the hottest points of the solar array.

In addition, with the inverter being the most likely point of failure in any solar system, in the event of a microinverter replacement, the labor required is much higher, as the solar panels would need to be removed to perform this repair, which would require a crew to access the roof and safely perform the work.  A string inverter replacement is much simpler, and should it every be needed, it can be performed with a single technician- no roof access required.

 

Optimizer System: the best of both worlds.

A diagram showing the connections between a power optimizer system attached to an inverter and monitoring systemA DC optimizer system is a great compromise between the two inverter types. It takes the production advantages and monitoring capabilities of a microinverter system, and combines this with the ease of service and system separation of a string inverter system.

DC optimizers do not house the more complicated and harder working capacitors and components that are involved with changing the current from DC to AC. These are located on the inverter- which is placed on the side of the home or basement, away from the hot solar panels.

Apex Solar Power employs Solar Edge DC optimizers as its standard offering.