Contents
- Solar permitting timelines statistics: residential permit review distributions
- Solar permitting timelines statistics: annual review and phase benchmarks
- solar permitting timelines statistics: pandemic-era review changes
- solar permitting timelines statistics: SolarAPP+ review outcomes and delays
- Solar permitting timelines: full permit-to-inspection duration
- Solar permitting timelines: evidence scope and large-scale facility context
- Sources
Solar permitting timelines statistics: residential permit review distributions
Permit review is one segment of a solar project’s timeline. In the NREL residential study, “AHJ Permit Review” runs from application submission to approval by the authority having jurisdiction (AHJ). The annual figures below are business days and describe a distribution across residential rooftop standalone PV projects, not a guaranteed turnaround for an individual application. Source: NREL, Residential Solar Adoption Timelines
| Year | 5th percentile | Median | 95th percentile |
|---|---|---|---|
| 2017 | 0 days | 5 days | 30 days |
| 2018 | 0 days | 5 days | 30 days |
| 2019 | 0 days | 5 days | 29 days |
| 2020 | 0 days | 6 days | 35 days |
| 2021 | 0 days | 6 days | 29 days |
AHJ permit review, application submission to approval; business days. Source: NREL, Table B-3. NREL report
The 5th percentile is 0 days in each of the 5 years shown. This indicates that at least the shortest-duration portion of the measured distribution reached approval within the same recorded business day; it does not mean every permit was issued instantly. At the median, review is 5 business days in 2017, 2018, and 2019, then 6 in 2020 and 2021. The 95th-percentile figures show a longer tail: 30 days in 2017 and 2018, 29 in 2019, 35 in 2020, and 29 in 2021.
These percentiles answer different questions. The median marks the middle of the observed distribution, while the 95th percentile describes a much longer review duration than the median. The gap between the middle and upper tail means a single “typical” figure cannot describe all applications. The 2020 upper-tail value is the largest in this series, but the table alone does not establish why it changed or whether an individual jurisdiction followed the same pattern. Source: NREL, Table B-3
Solar permitting timelines statistics: annual review and phase benchmarks
The AHJ-only review figures can be compared with a broader measure in the same NREL study: “Review Phase (total).” This combined phase begins with the first application submission and ends with the last approval, including both AHJ permit and utility pre-install interconnection applications. The median durations below are business days. Because this measure includes utility review as well as AHJ permitting, it should not be treated as another label for AHJ permit review alone. Source: NREL, Tables B-2 and B-3
| Year | Median AHJ permit review | Mean AHJ permit review | Median combined review phase |
|---|---|---|---|
| 2017 | 5 days | 9 days | 8 days |
| 2018 | 5 days | 9 days | 8 days |
| 2019 | 5 days | 9 days | 7 days |
| 2020 | 6 days | 10 days | 10 days |
| 2021 | 6 days | 9 days | 9 days |
Review durations are business days. Combined review includes AHJ and utility pre-install applications. Source: NREL, Tables B-2 and B-3. NREL report
For AHJ review, the annual mean is above the median in every year shown: 9 versus 5 business days in 2017, 2018, and 2019; 10 versus 6 in 2020; and 9 versus 6 in 2021. This pattern is consistent with some longer reviews lifting the average above the midpoint, though these summaries do not describe the shape of every jurisdiction’s distribution. The combined review median is 8 days in 2017 and 2018, 7 in 2019, 10 in 2020, and 9 in 2021. Its values need not move in lockstep with AHJ-only review because its boundaries and included approvals differ.
For readers comparing benchmarks, the distinction matters operationally: an AHJ review metric ends at permit approval, while the combined review phase also includes utility pre-install interconnection applications and ends at the last approval. Neither one is the full time from application through installation and final inspection. Source: NREL, Tables B-2 and B-3
solar permitting timelines statistics: pandemic-era review changes
NREL reports several comparisons around 2020 and 2021, but they use different units of analysis. One is a project-level difference from the project’s AHJ 2019 median. In that comparison, the median permit-review difference is +1 day in 2020 and +1 day in 2021. The mean difference is 4.6 days in 2020 and 3.9 days in 2021. Positive values denote increases relative to the AHJ’s 2019 median. These are differences, not absolute permit review durations. Source: NREL, Table B-12
A separate AHJ-level comparison reports the mean change in median permit-review timelines from 2019 to 2020. It is 1.5 days across the entire analyzed set, 1.0 day in the report-defined subset, 1.6 days among online-instant AHJs, and 2.0 days among in-person-only AHJs. The online-instant category does not imply that every permit was instant: NREL notes that 2 of 6 such AHJs saw increases in 2020, and the cause is unknown. The group means should be read as results for these defined sets, not as a ranking of all permitting offices. Source: NREL, Table B-13 and footnote
The report also presents a before-and-after model comparing phases beginning before and after March 2020, with controls for other factors. Its AHJ permit-review coefficient is 2.04 business days and is statistically significant at p<0.05. This is a model coefficient for the study’s residential PV sample and specification; it is not a universal estimate for every AHJ or a forecast of current review times. Source: NREL, Table 4
Together, these measurements document longer review durations in several pandemic-era comparisons, while their definitions remain distinct: project-level differences against an AHJ baseline, AHJ-level changes in median, and a modeled before/after coefficient. The figures do not establish a cause for the changes. Source: NREL, Tables B-12, B-13, and 4
solar permitting timelines statistics: SolarAPP+ review outcomes and delays
A separate NREL review examines 2023 permitting in AHJs participating in SolarAPP+. For the report’s review-time comparisons, duration means business days from permit submission to issuance, and the comparison excludes revisions. Traditional PV-only permits had a median review time of 7 business days across the included AHJs. SolarAPP+ PV-only projects had a median of 0 days. In the PV-plus-storage comparison, traditional projects had a median of 9 business days, while SolarAPP+ projects had a median of 0 days. Source: NREL, SolarAPP+ Performance Review, Section 3.2
| 2023 permit category | Traditional median review | SolarAPP+ median review |
|---|---|---|
| PV-only | 7 business days | 0 business days |
| PV-plus-storage | 9 business days | 0 business days |
Median submission-to-issuance review duration; revisions excluded. Source: NREL, Section 3.2. NREL report
The report also describes the long-duration portion of the review comparison. Around 13% of traditional permits took more than 30 business days to be issued, and around 4% took longer than 60 business days. For SolarAPP+ permits, fewer than 1% took longer than 30 days. These shares put the median in context: the median summarizes the center, while the threshold shares show how often review exceeded specified durations. They are not completion rates for the full installation process. Source: NREL, Section 3.2
The comparison is limited to participating AHJs and the report’s comparison samples. NREL cautions that results do not control for potential confounding factors and may not represent impacts in other AHJs. The SolarAPP+ zero-day median describes the measured review period for code-compliant applications; it does not mean the entire project reached installation or passed inspection on the permit submission date. Source: NREL, Sections 3.2 and report limitations
Solar permitting timelines: full permit-to-inspection duration
Permit issuance is only one milestone. NREL’s 2023 adoption-timeline comparison follows projects from permit submission to final passed inspection. For PV-only permits across 27 AHJs with available durations for both groups, the median was 33 business days for SolarAPP+ permits and 47.5 business days for traditional permits. For PV-plus-storage permits across 19 AHJs with available data, the median was 29 business days for SolarAPP+ and 52 business days for traditional permits. Source: NREL, SolarAPP+ Performance Review, Section 3.4
| Project type and comparison scope | SolarAPP+ median | Traditional median |
|---|---|---|
| PV-only; 27 AHJs with paired duration data | 33 business days | 47.5 business days |
| PV-plus-storage; 19 AHJs with available data | 29 business days | 52 business days |
Permit submission to final passed inspection, 2023. Source: NREL, Section 3.4. NREL report
These figures have a wider endpoint than permit-review duration: they include the time from submission through the final passed inspection. They therefore show why a fast permit review and a shorter overall timeline are not interchangeable measures. The reported medians are specific to the AHJs and project groups described, and the comparison should not be generalized beyond that scope. Source: NREL, Section 3.4
Solar permitting timelines: evidence scope and large-scale facility context
The NREL residential study’s final dataset covered 131,384 installs across 938 AHJs and 238 utility service territories in 29 states, from 2017 through 2021. It represented about 7% of U.S. installs over that study period. The analysis was limited to rooftop systems of 10 kW or less and standalone PV without storage. It excluded projects with total timelines over 260 business days, and the results were weighted toward larger installers. They do not cover every state, utility, or AHJ. Source: NREL, Residential Solar Adoption Timelines, Section 3.1 and study notes
A different scale of evidence appears in Berkeley Lab’s October 2026 report on large-scale wind and solar facilities. Its analysis spans 29 states and more than 400 counties. The publication page says local county or sub-county authorities move through permitting at near 200 days. It also reports that more than 87% of state-level permitting processes and 93% of sub-state-level processes resulted in a granted permit. These are large-scale facility results; they are not residential rooftop permit-review durations and should not be compared as though the populations or process definitions were the same. Source: Berkeley Lab, Permit outcomes and timelines
Across these sources, the useful distinction is the measure’s endpoint and population: residential AHJ submission-to-approval distributions, combined AHJ-and-utility review, participating-AHJ SolarAPP+ comparisons, full permit-to-inspection durations, and large-scale facility permitting outcomes each describe a different slice of solar permitting. The figures retain their original periods and units, and the residential and large-scale evidence should be interpreted within its stated scope.