Solar Site Survey: Measuring Your Sun Before You Build

Every disappointing solar project in the world shares one ancestor: a site assessment that never happened. The panel under the summer-leafy oak, the array behind the neighbor's December roofline, the balcony that turns out to face the wrong kind of south — all preventable by the survey this guide teaches: an afternoon of observation, a season of casual notes, and a few honest tools between free and cheap. This is the reference every build in the catalog cites before its first bracket goes up.

Sun paths: the geometry worth internalizing

The survey's foundation is one mental model: the sun's daily arc swings dramatically by season — high and long across the sky in summer, low and short in winter — and every shading question is really a question about which season's arc an obstacle intersects. The consequences run this series: winter builds (the air heater, the holiday rig) survey against the low December arc where fences and rooflines cast their longest shadows; summer builds (the pool loop, the irrigation pump) enjoy the forgiving high arc; and year-round systems — the cameras, gates, and cabin arrays — must clear the winter arc, full stop, because a system sized to summer is a system that fails in the season it's needed most. The corollary every surveyor learns by heart: the deciduous tree is a seasonal liar — bare and harmless at the January survey, a full solar eclipse by June — so the survey reads trees by their leafed-out silhouette regardless of when you're standing there.

The free tier: eyes, shadows, and a Saturday

The zero-dollar survey answers most residential questions. The all-day watch: visit the candidate spot at morning, noon, and late afternoon on one clear day, noting when direct sun arrives and leaves — the middle-of-day hours are the harvest that matters, and a spot shaded through them is disqualified regardless of its lovely mornings. The shadow read: obstacles telegraph their winter behavior — the lower the sun, the longer the shadow — so a fence or roofline that shades the spot's southern approach in the survey's afternoon will own it in December; conversely, generous open sky to the south is the all-clear no app improves on. The compass check: phone compass in hand, confirm the honest south (and the mount's achievable tilt toward it), remembering the series' standing tilt guidance — roughly latitude for year-round, steeper for winter missions, shallower for summer ones. A Saturday of this, written down, beats the untested assumptions behind most of the internet's sad-panel photos.

The tool tier: apps, meters, and the year in an afternoon

Modest tools compress the seasons. Sun-path apps — the augmented-reality class that overlays the sun's arcs on the phone's camera view — are the survey's great cheat: stand at the candidate spot, sweep the horizon, and watch every season's arc drawn against your actual trees and rooflines, turning the deciduous-liar problem and the December-roofline question into a sixty-second visualization. Irradiance and shading meters formalize it for bigger commitments: the pro-style sun-eye tools and the humble pyranometer class measure rather than infer, and the weather station's radiation sensor extends the survey into a running dataset — a full year of your site's actual insolation, the gold standard every array-sizing decision afterward consults. The datasets close the loop: the public solar-resource maps and calculators translate your location into monthly harvest estimates that, corrected by your measured shading, turn the whole survey into the number the runtime calculator and every build's sizing section actually wants: honest daily watt-hours, by season, at your site.

The surveyor's pocket kit

The whole discipline fits in a jacket pocket: the phone's compass and a sun-path AR app, a notepad for the all-day watch, and — for the properties graduating to the map habit — the irradiance meter tier and the pole saw's honest place in the solar toolkit. Cheap instruments, expensive mistakes prevented; the ratio is the survey's entire sales pitch.

Reading the results: the site verdicts

Surveys resolve into four verdicts worth naming. The green light: open southern sky through the midday hours in the mission's season — build with confidence, tilt per the mission, done. The relocation: the spot fails but the property doesn't — the panel moves to the sunny fence post, the shed's other face, the yard rack, with the wire run priced per the wiring guide's drop math (a longer run to real sun beats a short run to shade, every time — the series' most-repeated siting sermon). The seasonal compromise: good summer sun, blocked winter — fine for the summer missions, disqualifying for year-round loads unless battery margin and honest expectations both stretch. The red light: deep, unmovable shade — at which point the survey has done its finest work, redirecting the budget toward the battery-or-wire alternatives before the panel gets bought, mounted, and photographed sadly. Every verdict is cheaper on survey day than on commissioning day; that's the entire economics of the afternoon.

The survey habit at property scale

Veterans stop surveying spots and start maintaining a sun map: one property walk per solstice with the sun-path app, the good zones and dead zones sketched onto a rough plan, updated as trees grow and structures rise — because shade creeps annually and the map catches it before output graphs do. The map then feeds every future decision this series generates: the next build's panel goes to a mapped green zone by default, the mount comparison's adjustable-tilt case gets argued with real seasonal numbers, and the pruning saw earns its place in the solar toolkit (the cheapest capacity upgrade on many properties is an afternoon with a pole saw and the neighbor's blessing). The survey, like the weather station it pairs with, converts the property from anecdote to dataset — and every sad-panel photo it prevents was paid for by one honest Saturday.