Letter Re: Backup Electric Power Design Considerations

HJL, I believe R.V. and Expat are referring to AC Coupled inverters. I’ve installed hundreds of offgrid solar systems from 300 to 30,000 watts and I have never used an AC coupled system for an offgrid install. Mainly because it requires more fancy equipment and customization. I don’t feel it gives my customers a good value; it is more complex and less durable. That’s not to say there are not scenarios where it may be the better choice, especially if you are grid tied and net metering. If your readers are interested in the technology, search for “AC Coupled Battery Backup” on the Internet. If I had to go AC coupled with batteries, I would choose a combination of Outback, SMA, or Enphase. If you are looking for a durable offgrid system, 99% of the time, DC coupled is the better choice…for now. – K.K.