Solavin

Solavin is a research-oriented web application for inspecting photovoltaic current-voltage (I-V) sweeps. It extracts I_sc, V_oc, P_max, V_mp, I_mp, fill factor, local slope estimates of R_s/R_sh, and—when area and irradiance are provided—power-conversion efficiency.

The application is designed to make questionable data visible rather than turn it into precise-looking numbers. Missing cells remain missing, unbracketed V_oc values are reported as lower bounds, dependent metrics are withheld when they cannot be supported, and every export carries analysis status and provenance.

Solavin validates calculations performed on supplied data. It does not calibrate an instrument or certify a photovoltaic measurement to IEC 60904-1. Measurement uncertainty, spectral mismatch, temperature control, irradiance uniformity, sweep protocol, contact quality, and instrument calibration remain the operator's responsibility.

Developed by John Myron Uy, under the guidance of Prof. Raymund Sarmiento — Research Laboratory, Solar Cell Characterization.

What researchers get

• Piecewise-linear I-V and P-V plots that do not invent smoothed extrema.
• Exact maximum-power optimization on each measured linear segment.
• Voltage-keyed alignment across sparse channels, so one missing cell cannot shift later measurements onto the wrong voltage.
• Explicit pass, review, and invalid channel states.
• CSV and three-sheet XLSX exports:
  • Metrics — values, units, per-metric status, quality flags, source, and analysis version.
  • Raw Data — signed measurements aligned by voltage with gaps preserved.
  • Metadata — conventions, handling rules, source, and import warnings.
• Safe .xlsx and RFC 4180 CSV ingestion with a 25 MB browser limit.
• A deterministic offline assistant that only summarizes validated extracted results.
• A normal hosted build and a self-contained offline HTML build.

Analysis definitions

All scientific calculations live in src/lib/ivAnalysis.js. Current uses the generator convention: current is positive while the device produces positive V·I power and negative beyond V_oc.

Quantity	Definition and validity rule
Isc	Signed current at V = 0. Uses an exact sample, interpolation across zero, or a flagged nearest-pair extrapolation.
Voc	First non-negative-voltage positive-to-negative current crossing, linearly interpolated. If no crossing is measured, the highest measured voltage is only a lower bound.
Pmax	Maximum of V·I in the measured power quadrant. The maximum is solved analytically on every piecewise-linear segment.
Vmp, Imp	Coordinates of the same piecewise-linear Pmax solution.
FF	Pmax / (Isc·Voc). Withheld if Voc is unbracketed; out-of-range results are reported as errors, never clamped.
Rs	|dV/dI| from a local multi-point linear fit near Voc. Withheld when Voc is unbracketed or the fit is degenerate.
Rsh	|dV/dI| from a local multi-point linear fit near V = 0.
η	Pmax / (G·A), with P in W, G in W/m², and illuminated area entered in cm².

R_s and R_sh are local light-sweep slope estimates, not a substitute for uncertainty-aware parameter fitting or dark-I-V analysis.

Validation

The automated suite currently contains 53 tests, including:

• 300 deterministic randomized linear curves checked against closed-form I_sc, V_oc, P_max, V_mp, I_mp, and FF solutions.
• Six continuous single-diode curves spanning nanoampere to ampere scales, checked against an independent golden-section maximum-power oracle.
• Current-scale invariance checks.
• Censored sweeps, nonphysical curves, duplicate voltages, all-negative and sparse sweeps.
• Blank cells, duplicate/blank headers, malicious labels, quoted and malformed CSV, input safety limits, and spreadsheet-formula neutralization.
• Raw-data alignment, status/provenance export, and invalid efficiency inputs.

Coverage gates apply to the scientific core: at least 90% statements, 80% branches, 90% functions, and 90% lines. CI additionally performs a high-severity dependency audit, both production builds, and a real-Chromium import, visualization, assistant, and CSV/XLSX download smoke test.

See docs/VALIDATION.md for the audit register, tolerances, reproducibility commands, and residual limitations.

Input format

Use .xlsx or .csv. Column A is voltage in volts. Each subsequent column is one signed current sweep in amperes, and row 1 contains channel labels.

Voltage (V),Focused Laser,-2 mm,+6 mm Focus
0,1.539e-6,1.460e-6,1.583e-6
0.05,1.528e-6,1.456e-6,1.565e-6
2.50,-3.875e-6,-3.052e-6,-2.923e-6

Rules:

• Every accepted channel must contain at least three unique voltage setpoints with valid voltage-current pairs.
• Blank or nonnumeric current cells are skipped and reported; they are never converted to zero.
• Exact duplicate voltage setpoints are averaged and flagged.
• Blank and duplicate channel headers are assigned unique visible names.
• Legacy .xls files are intentionally rejected; convert them to .xlsx or CSV first.

The bundled example is examples/sample_iv_data.csv.

Run and verify

Node.js 22 is the CI reference runtime.

npm ci
npm run validate       # dependency audit, coverage-gated tests, both builds
npm run test:e2e       # standalone build + real-browser smoke test
npm run dev            # local development server

Build targets:

npm run build              # dist/
npm run build:standalone   # dist-standalone/index.html
npm run build:all          # both

The standalone file contains the application code and can run from file:// without a backend. Browser profile and dataset storage is local and is not an authentication or access-control system.

Project map

src/
  lib/
    ivAnalysis.js
    ivAnalysis.test.js
    ivAnalysis.validation.test.js
    assistant.js
  components/
  App.jsx
docs/
  VALIDATION.md
examples/
  sample_iv_data.csv
tests/
  e2e.smoke.mjs
.github/workflows/
  ci.yml

Standards context

IEC 60904-1 defines measurement requirements for photovoltaic I-V characteristics; Solavin is an analysis and visualization layer, not an IEC conformity claim. NREL's photovoltaic measurement guidance likewise emphasizes calibration and uncertainty in the upstream measurement chain.

• IEC 60904-1:2020 — Photovoltaic devices, Part 1
• NREL — Trust But Verify: Creating and Using Highly Accurate Measurements in Solar Research

License and citation

MIT © 2026 John Myron Uy. Citation metadata is provided in CITATION.cff.