Lay the phone on the panel. Know if you’re facing the sun.

Field measurement for DIY and farm PV — Align, live sun path, and an honest order-of-magnitude yield. No ads.

The field problem

Guessing azimuth with a phone compass that doesn’t match true south. Apps that freeze heading or bury tools behind ads. kWh numbers that sound precise but aren’t bankable — you deserve honesty.

How it works

1. Compass Live Calibrate, keep clear of steel, watch the sun path — with what-if sliders and a true-north needle.

2. Align → Hold → Apply Phone face-up on the panel, top toward upslope. Hold the reading, then apply it to one array plane.

3. Forecast & share Sketch a coarse horizon, get an approximate annual AC estimate with a ± band, and take home a personal PDF or text report.

What Free does today

Measure

Align with crosshair and Hold. Azimuth and tilt for one plane. Weak-compass guidance. True north with WMM2025 declination.

See the sun

Compass Live: live sun path, GPS, device-top needle, and what-if sliders — so you see the season before you commit.

Estimate honestly

Order-of-magnitude annual AC after typical system losses, with a ± band — not a bankable study, and we say so.

Take it home

Personal PDF or text site report. Generic balcony / south-roof scenarios and CSV measured vs forecast — for your notes, not a sales deck.

Who it’s for

DIY balcony, farm, RV, and portable arrays — measure orientation today
Readers of Windy Farm off-grid and ESS essays who want a tool in the field
Not a substitute for string Voc/Vmp sizing, MPPT validation, or full electrical design software

Built with the farm story

Same author as the Wilczyska off-grid build — Robert Bala. PV Survey is the interactive layer for measuring arrays in the field, next to the essays on how the system grew. Start with From four panels to off-grid storage or the off-grid energy series. Financial tools (True Return) live on a different pillar — this page is Energy only.

Field note — Wilczyska (~49.7°N)

After Align on the south string, ~45° tilt toward south is a sensible year-round angle here — close to latitude. That is orientation guidance for DIY planning, not a bankable yield study.

~45° — year-round (recommended for the south string)
25–35° — summer bias
55–65° — winter bias
~5° — a deliberate low-tilt compromise (what we ran before)

In full summer sun the MPPT often already clips near its limit (~1100 W), so raising the south string toward 45° mainly helps winter and off-noon hours — not necessarily the summer peak.

Join the waitlist

Be first when TestFlight or the App Store opens. No spam — product updates for PV Survey only. Tag: pv-survey-waitlist.

Educational / DIY field tool — not a substitute for a licensed electrical design or bankable energy study. Phone sensors and a coarse horizon sketch are not LiDAR or SunEye. Yield figures are approximate (order of magnitude).

FAQ

Is the kWh number bankable?: No. It’s an order-of-magnitude annual AC estimate after typical losses, with a ± band — useful for DIY planning, not loans or bank studies.
Does Free Align stay free?: Yes. Align and Compass are the trusted free core. Pro is optional proof and handoff.
True north or magnetic?: Prefer true north. Declination uses WMM2025 so the needle matches the sky, not a fridge magnet.
Multi-plane east–west roofs?: Free applies to one plane. Multi-plane and deeper shading are soft-teased for Pro.
String sizing or inverter datasheet checks?: Out of scope. That’s a future Design line if we ever build it — not this app.
Languages?: In-app: English default with full Polish. This landing is English-first.
Privacy — what does the waitlist collect?: Email, consent text, and the waitlist tag pv-survey-waitlist. Field measurements stay on device; we don’t run ads.