pic of a micro-inverterI’d never heard of “micro-inverters” — until I surfed to Solardave.com and watched an interview Solar Dave did with an Astralux Solar representative on the new Enphase Energy micro-inverters.

editor's blog logoBasically, a solar-system with micro-inverters has an inverter on each and every solar panel on your system, as opposed to a centralized inverter for the entire system.

There are a number of advantages to the micro-inverter approach.

The two most significant advantages are:

  1. You’re not tied to a certain “string” arrangement, or a particular arrangement of solar panels, which requires that a certain number of solar panels be “stringed” together in order to work; being locked into particular string configurations can have a big impact on your system size, its output, and its cost.
  2. Micro-inverters ensure a more even and efficient energy output than a system with a centralized inverter.

The primary disadvantage is cost. According to my solar consultant, Brian Sharpe at REC Solar, a micro-inverter system is substantially more expensive than one with a single, centralized inverter.

As I look into things more, though, it seems to me that we might want to take another look at “cost” and how we’re calculating it.

25-year life span
According to Enphase, the micro-inverters last 25 years. Of course, Enphase only guarantees the micro-inverters for 15 years.

In comparison, Sunny Boy offers 10-year warranties on its inverters. And it’s my understanding that a central inverter lasts no more than 15 years. At which point, you’ll need to plop down probably a couple thousand dollars (or more) to replace it.

And solar companies — to the best of my knowledge — do not, that’s right, they do not include the cost of having to replace your inverter in the long-term savings projections they give you (that’s a story I’d like to investigate more down the road).

In any case, micro-inverters are really beginning to intrigue me.

I wonder — if you add in the cost of replacing a centralized inverter at year 10 or 12, plus lower efficiency of the system, which means more panels, and if the micro-inverters really do last 100 years, maybe it’s not more expensive to go with micro-inverters…

I wonder — if you add in the cost of replacing a centralized inverter at year 10 or 12, plus lower efficiency of the system, which means more panels, and if the micro-inverters really do last 100 years, maybe it’s not more expensive to go with micro-inverters…

I’m definitely going to talk to Brian more about this. But first things first. First, we have to figure out what size solar system Xcel Energy will allow us to have and still receive an Xcel rebate.

I just bought two Econo-heat “Envi” 450-watt, high efficiency wall heaters and we’re going to be passing the receipts on to Xcel.

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The goal: To boost our electric consumption so that we can qualify for a bigger solar system.

On the surface, it seems rather backward, and decidedly “un-green” to boost our electric consumption. However, the Econo-heat electric heaters will allow us to turn down our gas furnace — to as low as 50 degrees for 10-hour periods at night. So, we should save a considerable amount of natural gas.

I’m not sure how Xcel will respond to our purchase of these heaters and our submitting the receipts. But this is what they’ve asked other customers who want to “over-size” their solar system to do: produce a receipt for the items which will increase one’s household electric use.

Stay tuned!

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