Micro Inverters or AC Modules? What's the difference?
I'm starting a new project on my vacation house and just using micro inverters (1 x 20A circuit). Should I use "AC Modules" instead? What's the difference? Isn't this just a marketing spin on "micro inverters"?
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This is a much more complicated issue than it should be - but yes, an AC module is a PV module with a micro inverter on it. The difference is that the AC module is tested as an assembly and therefore UL listed as an assembly - essentially taking the DC component out of the equation (Arc faults, DC disconnects, etc..). So, in theory, design and permitting should be no different that installing any type of AC branch circuit. Of course, nothing is quite as simple as it should be with solar energy - AHJs have to be very careful with new products and they mostly still look at AC modules as PV modules with Micro Inverters. This will probably change as adoption of the new assemblies expands.
AC modules are UL listed as a complete unit comprised of a micro-inverter and a PV module. Anything else, even if the PV module comes with a micro-inverter attached, is a seperate assembly. Here's what an AC module can do for you:You don't have to assemble the micro-inverter and PV module on siteAC modules don't have the DC grounding requirements that a micro-inverter and PV module have. AC modules are still a little hard to come by. Do you need one? Only if you don't want to put the PV module and micro-inverter together yourself. It can be difficult to determine if a PV module with a micro-inverter attached is actually an AC module. It has to have a listing label attached that says it is listed as an AC module. If it has a listing label on the PV module that says it is a listed module and a label on the inverter that says it is a listed inverter but no label that says it is a listed AC module then it's not a listed AC module no matter what someone says.
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Here's what an AC module can do for you: You don't have to assemble the micro-inverter and PV module on site AC modules don't have the DC grounding requirements that a micro-inverter and PV module have.
AC modules are still a little hard to come by. Do you need one? Only if you don't want to put the PV module and micro-inverter together yourself.
It can be difficult to determine if a PV module with a micro-inverter attached is actually an AC module. It has to have a listing label attached that says it is listed as an AC module. If it has a listing label on the PV module that says it is a listed module and a label on the inverter that says it is a listed inverter but no label that says it is a listed AC module then it's not a listed AC module no matter what someone says.