When I was studying for the exam, the most important element was using free NABCEP Certification study resources. What took a huge amount of time was identifying the best resources and organizing everything. The test is segmented in separate segments, so you'll need to organize your studying for each segment. Here's the best video resource I found for each segment of the test. The outline of the exam is published in the NABCEP Job Task Analysis.
I've installed a 300kW of solar PV and I created this site after studying for the NABCEP PV Installers exam. I created a set of free cliff notes to help me easily skim through all the content and found the best study guide I could find was HeatSpring's NABCEP PV Installer Certification. If you want to get 10% off this course, you can review the course and get the discount here.
Free Study Resources
A review of the best resources that I've found for studying for the NABCEP PV Installer Exam based on my experience passing the exam.
Download 75 NABCEP Prep Questions for Free
An awesome resource to help your studying published by HeatSpring.