Early Design Solar PV Reference Tool
Free Early Design Solar PV Reference Tool for California
A resource from A2 Efficiency — free to use, no strings attached
Early-stage design decisions carry the most leverage in reaching net zero. But detailed energy modeling often comes too late in the process to meaningfully influence form, orientation, or roof configuration. We built this tool to close that gap.
The CA Solar PV Early Design Estimator is a free downloadable spreadsheet for architects and consultants working toward the AIA 2030 Commitment — or for anyone who needs a fast, reliable solar sanity check during schematic design and design development.
What It Does
The tool translates solar roof area, system capacity, or building footprint into an estimated annual energy output expressed in kBtu/sf/yr — the same unit used for EUI reporting in the AIA 2030 Design Data Exchange (DDx). No energy modeling software required.
It is organized into three parts:
Part 1 — Solar Output by California City
Annual solar yield for ten California climate zones, pre-calculated for a standard efficiency panel (21%), 15° tilt, south-facing orientation, and an 80% system derate factor. Values are expressed in kWh/kW, kWh/ft², and kBtu/ft² of roof area — so you can work from whatever information you have at hand.
Part 2 — Quick Calculation Guide
Three simple formulas show how to convert roof area, system size in kW, or building footprint and story count into an EUI offset. The worked examples are calibrated to a Southern California city so you can sanity-check your math at a glance.
Part 3 — AIA 2030 EUI Targets
A reference table of CBECS 2018 national median baselines and the corresponding AIA 2030 Challenge targets — 70% reduction by 2025, net zero by 2030 — for twelve common building types including office, school, multifamily, retail, and healthcare.
Who It’s For
Architects pursuing the AIA 2030 Commitment who need to estimate a solar EUI offset before an energy model is available
Energy consultants and sustainability advisors supporting early design trade-off studies
Design teams exploring massing options where roof area and solar potential vary between schemes
Anyone presenting net zero feasibility to a client or design team at concept stage
Ground Rules
This tool is intentionally simplified. It uses a single panel type, a single tilt, and climate-averaged annual yield values derived from NREL PVWatts data. It is appropriate for early concept and schematic design only.
For permit submittals, owner reporting, and final AIA 2030 DDx entries, use a full energy model calibrated to your specific project. The tool says this clearly — we wanted it in the tool itself, not just in the fine print.
Download
Download the CA Solar PV Early Design Estimator
Free to use and share. No sign-up required. If you find it useful, we'd love to hear about the project — reach out to us at info@a2efficiency.com.
Sources: NREL PVWatts v8 | EIA CBECS 2018 | AIA 2030 Challenge
Tool version 1.0 — February 2025