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Solar Design Lab andSolarAPP+
Heads up: SolarAPP+ isn't a competitor. It's a permit-issuance form for participating AHJs. We don't compete with it; we feed it. Here's what each one actually does and where they fit together.
What SolarAPP+ actually is
A permit form, not a design tool.
SolarAPP+ is an automated permit-review checklist developed by NREL and the DOE. At participating AHJs, you submit a planset (that you designed elsewhere), pass an automated rules check, and the AHJ auto-issues your permit instead of routing through plan review.
That's it. It doesn't draw the planset. It doesn't generate the single-line. It doesn't size conductors. It doesn't run voltage drop. It doesn't produce a structural calc. It doesn't stamp. It's a form that decides whether the planset you already produced is permittable on its own checklist.
Where it works (and doesn't)
- ~160 jurisdictions have adopted SolarAPP+ as of late 2025 (per DOE data). The US has roughly 20,000 permitting jurisdictions. Adoption is concentrated in Arizona and California. Most installs still go through traditional plan review.
- Eligibility is narrow: 1-2 family dwellings, townhomes ≤3 stories, ADUs. No ground mounts, no commercial, no multifamily, no mobile homes, no ballasted systems.
- Equipment must be on the CEC list. If your panel/inverter manufacturer hasn't submitted to CEC, the install can't go through SolarAPP+. You fall back to traditional permitting.
- Doesn't replace utility interconnection. That's still a separate 15-90 business day process.
- Tough jurisdictions like HVHZ Florida aren't a fit at all. Site- specific structural and uplift requirements need real engineering documentation, not a checklist.
How Solar Design Lab fits with SolarAPP+
We make the planset. SolarAPP+ speeds up the AHJ stamp on the back end.
The two work together at participating AHJs. Solar Design Lab handles the upstream. Design, single-line, conductor schedule, voltage drop, label package, structural, PE stamp. SolarAPP+ handles step six: getting the AHJ to issue the permit on a planset that already exists.
At a SolarAPP+ jurisdiction
Design in SDLstamp in SDLsubmit to SolarAPP+auto-issued
Everywhere else (the other 19,840 AHJs)
Design in SDLstamp in SDLsubmit to AHJ
SolarAPP+ is a useful permit shortcut at supported AHJs. Solar Design Lab is the system that produces the planset SolarAPP+ accepts.
Try it on your next planset. No card required.