Knowing how to comply with California’s Rule 21, which mandates smart inverters for all solar projects (and was recently tweaked to align with the state’s passage of SB100), is a good idea given that industry insiders believe states like Hawaii, Nevada, Arizona, Vermont, and Massachusetts will follow suit. This post explains what the rules are and how to comply with the current phase (choose an inverter certified under UL 1741-SA and use the right settings). Check the article for more info.