The Data Source Behind This Page, and Why It Is Not LBNL
Lawrence Berkeley National Laboratory’s Tracking the Sun report is the publisher most commonly cited for state-level distributed solar saturation data, and it was the intended source for this page. LBNL’s own site was not reachable for this research, and no other source could confirm LBNL’s specific state-by-state figures directly. The numbers below instead come from the Institute for Local Self-Reliance’s “The State(s) of Distributed Solar, 2024 Update,” a separate publisher analyzing the same underlying question, state-level distributed solar saturation, verified here through a university extension program that names ILSR as its source. If this topic needs to cite LBNL specifically, these figures are not a substitute; they are the closest verified alternative found.
Which States Have Crossed the Saturation Threshold
By the end of 2024, 23 states and the District of Columbia had reached a distributed solar saturation of more than 100 watts per capita, roughly one household in 25, per ILSR’s report. Minnesota led the states with individual figures available at 211 watts per household. Illinois followed at 147 watts per household, Iowa at 103, and Wisconsin at roughly 46, closer to one in every 100 Wisconsin households than the 1-in-25 threshold the broader 23-state group has crossed.
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Book a Solar CallWhy Minnesota Runs Ahead of Wisconsin by More Than Adoption Alone
ILSR’s own report flags a caveat worth carrying into any comparison built on these numbers: state totals reflect policy differences as much as raw household adoption. Minnesota leads all states in the amount of community solar it hosts, a policy structure that lets renters and homeowners without a suitable roof still subscribe to a solar project. Wisconsin, by contrast, does not yet have a law enabling third-party community solar farms. A state’s watts-per-household figure is a mix of how many homeowners chose solar and how many policy pathways existed for them to participate at all, not adoption in isolation.
Stock Versus Flow: Why This Is Not a Quarterly Install Number
The saturation figures above describe a stock, solar capacity already sitting on rooftops, measured against a state’s population. That is a different measure from new-installation volume, the flow of capacity being added right now. SEIA reports 7.8 GWdc of new US solar capacity installed nationally in Q1 2026 alone, a figure that adds to the state totals above rather than replacing them. A state can show high saturation from a decade of cumulative installs even in a quarter where new volume is falling nationally, worth keeping separate when reading either number on its own.
The Numbers
By the end of 2024, distributed solar reached a saturation of more than 100 watts per capita, roughly one household in 25, in 23 states and the District of Columbia.
University of Wisconsin-Madison Division of Extension, citing the Institute for Local Self-Reliance
Minnesota leads named states at 211 watts of distributed solar per household.
Illinois follows at 147 watts per household, Iowa at 103 watts per household.
Wisconsin sits at roughly 46 watts per household, close to one in every 100 Wisconsin households, well below the 23-state saturation-threshold group.
For scale on new volume rather than existing saturation: SEIA reports 7.8 GWdc of new US solar capacity installed nationally in Q1 2026 alone.
Sources
The external data in this article draws on the sources below. Figures described in the text as estimates or industry triangulations are directional and are not attributed to a single dataset.
- University of Wisconsin-Madison Division of Extension, State of Distributed Solar, citing the Institute for Local Self-Reliance
- SEIA, Q2 2026 Solar Market Insight Report