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Will AC PV modules ever succeed?

Mon Sep 21, 2015 9:34 am

According to this article in PV Magazine, SolarWorld will begin building PV modules with Enphase S-series microinverters integrated into the module. Assumedly, this integrated PV module will come equipped with only an Enphase Engage pigtail and would be capable of functioning in either 1-phase or 3-phase systems depending on which Engage cable it is connected into.

I suspect Enphase is interested in this integration partly because Enphase has been virtually shut out of the German PV market and SolarWorld is a German manufacturer. This joint agreement could give them an opportunity to make better progress in that country.

But this idea of an "AC PV Module" has always failed in the past. Will the outcome of this venture be any different?

It's clear that both the MTBF and the life of a PV module with integrated inverter electronics will be lower than that of one with only integrated protection diodes. PV modules by themselves have very long life and high MTBF. I've heard 600 years for PV MTBF and many modules have a life of three, four or five decades, if not longer. Even if you integrate an inverter which also has a 600-year MTBF (about the current measured field value of Enphase's M215 product), then the MTBF of the integrated module becomes only 300 years. But if the MTBF of the inverter turns out to be only 100 years, then the overall module MTBF is only 86 years, which is too low for this application. Life will be limited by the shorter life of the two. If the inverter has a 30-year life, that will likely limit the overall module.

OTOH, there may be failures related to the DC wiring which are eliminated by integrating the inverter. It's even possible that this failure mode could prove to be the biggest long-term failure mode with modern microinverters than the electronics are themselves, so this could be significant.

I don't know if this latest attempt to build "AC PV Modules" will succeed or not, but it will be interesting to watch!
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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