To Use or Not to Use Solar Micro-Inverters

Micro-inverters are readily available, as well as module level optimizers in combination with string inverters.

It is my opinion that micro-inverters mainly shine in multiple orientation sites, such as houses with east west and south facing orientations, in cases of shading, and on 10kW and smaller applications.

I think that they are best used for multiple small applications because string planning and design is basically eliminated. On large applications design becomes more complex and where it costs more to go micro on small jobs the expense goes through the roof on large applications.

Micro-inverters mounted directly under panels create a hot spot which is counter-productive.

We’ve installed Enphase micro-inverters side by side with an SMA string inverter metering them separately and there is no significant difference in performance after one year’s data collection.

There is the option of DC power optimizers such as Azuray, or IT based optimizers such as Tigo. These provide safety features in roof applications and performance features in less than perfect array conditions, such as poor quality modules, multiple orientations, and crafty craftsmanship.

This site is perfect though, a ground mount, plus we’re considering top of the line panels and inverters.

It is my learned opinion that the money put toward high quality panels, orientation design, string inverters, and careful installation practices is better spent, thus assuaging the higher cost of micro-inverters or power optimizers to fix the design problems and low end panels.

I consider the risk to be less of installing tried, true, and actively improved over ten more years string inverters than to jump for the cutting edge rapidly changing and currently testing micro inverters.

If power optimizers are the real future there are many that work with a variety of string inverters that could easily be integrated into the system in 5-10-20 years.

It can be tough to balance the new and exciting with the tried and true. But in this case the tried and true seems to be the best way forward.

What do you think?

-Sam