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What 1,200 W Means in US Plug-In Solar Laws

Most state plug-in solar bills cap a system at 1,200 watts. In many laws the figure is expressed as inverter or AC output, but the exact wording differs: Maryland limits the power supplied back to the building, Utah and Connecticut use maximum power output, and other laws use inverter capacity or nameplate output. It is not the panels' DC nameplate rating.

How the bills describe it

The wording varies but points at the same measurement. New York's bill sets the limit as "1,200 W aggregate continuous AC inverter nameplate output" (New York). Vermont's act allows a "maximum combined inverter capacity of not more than 1,200 W" (Vermont). Several states apply the cap per meter, per customer, or per service address; the exact unit is in each statute.

Bills and statutes that use 1,200 W

Where the number is different

Not every state uses 1,200 W. Colorado sets its cap at 1,920 W. Maine uses two tiers: up to 420 W without an electrician requirement, and up to 1,200 W when a Maine-licensed electrician installs the system. Several laws also exempt devices rated at or below 391 W from certain product-listing provisions, including Virginia and Colorado. Illinois's SB 3104, still in committee, uses 391 watts or less in its synopsis, an unusually low figure.

The numbers above come straight from the linked bills and statutes. How the cap is measured, per meter, per customer, per address, differs by state, so check the text for the one that applies to you.