March / 31  / 2016
Why microinverters are a safer design for solar

Solar power is gaining a coalition of fans, their numbers growing as PV spreads around the globe. But many emergency responders aren't yet sold, and understandably so. They, and others, are concerned with the electrical safety of these new and often unfamiliar systems. The idea of high-voltage DC sizzling across a rooftop is a stark prospect for anyone who might come in contact with a PV array while battling a building fire, or even performing routine maintenance.

Seeing the need for safety standards, regulators enacted "Rapid Shutdown" requirements (found in NEC 2014 690.12) to protect first responders from any high-voltage DC hazards that might remain after AC service has been disrupted or shut off. While manufacturers have responded to NEC 2014 with varying strategies-including add-on "DC combiner boxes" for string inverter arrays-one popular PV product already has Rapid Shutdown built into every unit: the microinverter.

When the AC circuit goes down for any reason, each unit in a microinverter array performs its own shutdown function in just 100 milliseconds-100 times faster than the code-specified standard of 10 seconds for shutdown. System voltage at shutdown is about 30V DC, meeting the stringent NEC 2014 requirement and well below the 80-V threshold generally considered safe for contact.

Safety doesn't end there. Microinverters also offer safety advantages when it comes to the DC conductor requirement in the standard. For example, a system designed using APsystems microinverters will have no DC conductors energized more than 5 ft in length within a building or more than 10 ft from the array, which meets the NEC 2014 standard (and is already looking ahead to NEC 2017).

  Also, any present low-voltage lines will be located beneath solar modules, eliminating the chance of contact during rooftop activity.

Powerful, reliable, economical, microinverters have had plenty to recommend them since they entered the MLPE product field. As electrical codes evolve to protect responders and homeowners alike, the humble microinverter is not only meeting these tough new standards, but anticipating them.

By: Christopher Barrett, engineering and technical services manager for APsystems USA. Contact him at

To learn more, watch his webinar presentation here.
APsystems will exhibit at the upcoming NABCEP Continuing Education Conference

APsystems is sponsoring the "Module Level Power Electronics Options" panel discussion on April 5 at 1pm, with Christopher Barrett, our technical services manager, sharing his expertise among the distinguished panelists.  See full conference schedule here.

You can also see the APsystems microinverter line at booth 509 on the conference floor.
The North American Board of Certified Energy Practitioners offers professional certification and company accreditation programs to renewable energy professionals throughout North America.

The Continuing Ed Conference brings together solar pros with leading manufacturers like APsystems, ranked no. 2 in global market share among microinverter suppliers by shipments in 2014 (source: GTM Research).

See, then contact our sales team ( to see the APsystems microinverter line in sunny San Diego.

What our installers are saying:

"As a recent convert to APsystems microinverters, I'm very pleased with the product. I use your product in every case that I can because of the tech support. They always answer the phone, are always are helpful and friendly and if we get stuck, they always follow up to make sure we've resolved the issue. I can personally tell you this is NOT the industry standard, and it's quite refreshing to see a company working as hard as I am to get a system up and running."

- Troy Woody, Owner Hot Solar Solutions LLC

APsystems Installers:
Share your top projects

APsystems is looking for top solar installations to highlight in our newsletter and website.  If you've completed a dynamic residential or commercial project using APsystems microinverters, send the details (with photos, please) to the APsystems marketing team. Along with the project specs, we may include your company information and logo in our outreach to customers - a great cross-promotion opportunity.   Email 
600 Ericksen Ave NE, Suite 200, Seattle, WA 98110 |  844.666.7035  |

APsystems | 600 Ericksen Ave NE, Suite 200 | Seattle | WA | 98110