Part of DIY Wind Turbine

How to choose the right location for your wind turbine so it actually produces useful power instead of sitting in dead air.

Site Assessment

Why Site Assessment Matters

The single biggest factor determining whether your wind turbine succeeds or fails is where you put it. A well-built turbine in a poor location will produce almost nothing. A crude turbine in an excellent location will outperform it by ten to one. Wind energy follows the cube law — doubling wind speed produces eight times the power — so even small differences in average wind speed between locations translate into enormous differences in energy output.

Most people drastically overestimate how windy their chosen site is. We notice and remember strong gusts but ignore the long calm hours between them. Without proper site assessment, you may spend weeks building a turbine only to discover it spins uselessly in turbulent, obstructed air. An afternoon of careful observation and a few weeks of measurement can save you months of wasted effort.

Wind Resource Basics

Prevailing Wind Direction

Every region has a dominant wind direction — the direction wind comes from most of the time. In most temperate zones, prevailing winds blow from the west or southwest. Coastal areas often have onshore breezes during the day (from water to land) and offshore breezes at night (from land to water). Mountain valleys channel wind along their length.

To find your prevailing wind direction, observe over several days:

• Which direction do clouds move most of the time?
• Which side of buildings collects the most wind-driven debris?
• Which direction do weathered surfaces and lichen growth face? (Wind-exposed sides stay cleaner)
• Ask long-term residents or survivors who farmed the area

The Prevailing Wind Is Your Power Source

Orient everything around it. Your turbine must face into the prevailing wind with clear, unobstructed fetch (open distance) for at least 300 meters upwind. Obstacles in any other direction matter much less.

Seasonal Patterns

Wind speeds vary dramatically by season. Many regions are windiest in late autumn through early spring and calmest in midsummer. This is actually complementary to solar power, which peaks in summer — a compelling reason to combine both energy sources.

Note seasonal shifts in wind direction too. A site perfectly aligned for winter westerlies may be shielded during summer when winds shift to the south.

Obstacles and Wind Shadows

Every solid object creates a zone of disturbed, slowed air behind it called a wind shadow. The size of this shadow depends on the obstacle’s height and width.

Obstacle	Typical Height	Wind Shadow Length (Downwind)	Wind Shadow Height
Single-story building	4m	80m (20x height)	8m (2x height)
Two-story building	8m	160m	16m
Dense tree line	10m	200m	20m
Large barn or warehouse	6m	120m	12m
Hill or ridge	Varies	Turbulence extends 10-20x height on lee side	2-3x height

The wind shadow is not uniform. Immediately behind an obstacle, the air is turbulent and chaotic — useless for a turbine. Further downwind, the wind recovers but remains slower than the free stream. The rule of thumb: place your turbine at least 20 times the obstacle height downwind or 2 times the obstacle height above the obstacle.

Turbulence Destroys Turbines

Turbulent air does not just reduce power — it actively damages your turbine. Rapidly shifting wind directions create alternating stresses on blades, bearings, and the tower structure. A turbine in turbulent air will fail mechanically long before a turbine in clean air of the same average speed.

Upwind Obstacles Matter Most

An obstacle 100 meters upwind in the prevailing wind direction is devastating. The same obstacle 100 meters to the north when prevailing winds come from the west barely matters. Focus your attention on clearing or avoiding obstacles in the prevailing wind corridor.

The Ideal Site

The perfect wind turbine site has these characteristics:

1. Elevated — Hilltops, ridgelines, and raised ground experience faster and smoother wind than valleys and hollows. Even a 10-meter elevation advantage helps significantly.

2. Open fetch — At least 300 meters of clear, unobstructed ground upwind in the prevailing wind direction. Flat farmland, open water, or short grassland are ideal.

3. Smooth upwind terrain — Rough surfaces (forests, dense buildings, rocky ground) create turbulence that persists for hundreds of meters downwind. Smooth surfaces (water, mown grass, bare earth) produce clean, laminar flow.

4. Away from the lee side of hills — The downwind side of hills and ridges is the worst possible location. Wind accelerates over the top but creates severe turbulence on the lee side that can extend 10-20 times the hill height downwind.

5. Accessible — You need to transport materials to the site, erect a tower, and perform maintenance. A perfect site that requires a 2km hike through forest is impractical.

6. Close to where power is used — Every meter of wire between turbine and battery bank loses energy to resistance. Keep the distance under 100 meters if possible, or use thicker wire for longer runs.

The "Raised Hand" Test

Stand at your proposed site. Hold your hand straight out toward the prevailing wind. If you can see any obstacle taller than your hand (at arm’s length) in the upwind direction within 300 meters, that obstacle will affect your turbine. Move the site or plan for a taller tower.

Using Local Indicators

You do not need instruments to get a rough picture of wind exposure. Nature has been measuring for you.

Tree Deformation (Griggs-Putnam Index)

Trees exposed to persistent wind deform in predictable ways. This tells you about long-term average wind conditions:

Deformation Level	Description	Estimated Mean Wind Speed
0 — No deformation	Symmetrical canopy	Below 3 m/s (too low for generation)
1 — Brushing	Branches slightly bent downwind	3-4 m/s (marginal)
2 — Flagging	Branches extend only downwind, like a flag	4-5 m/s (usable)
3 — Throwing	Trunk leans slightly downwind	5-6 m/s (good)
4 — Clipping	Canopy trimmed on windward side, full growth only downwind	6-8 m/s (excellent)
5 — Carpeting	Tree grows nearly horizontal along ground	8+ m/s (outstanding, but may be too extreme for simple turbines)

Look at Isolated Trees

Trees in forests protect each other. Only isolated, exposed trees — lone trees in fields, trees on hilltops, trees at forest edges facing the wind — reliably indicate wind conditions.

Other Natural Indicators

• Flag behavior — Hang a strip of cloth or a flag at the proposed site and at alternative sites. Compare how they behave over the same period.
• Smoke — Light a small smoky fire and watch how quickly and consistently the smoke is carried away. Note the direction.
• Grass and crops — In open fields, persistent wind creates visible lean patterns in tall grass. Standing water develops wave patterns aligned with prevailing wind.
• Snow and sand drift — Accumulation patterns reveal wind channeling and acceleration zones. Snow builds up on the lee side of obstacles.
• Erosion patterns — Exposed soil, worn paint, and weathered surfaces indicate long-term wind exposure.

Mapping Your Site

Spend an afternoon walking your entire available area with a notebook. Sketch a rough map including:

1. All obstacles — buildings, walls, tree lines, dense vegetation, terrain features
2. Elevation changes — mark high points, low points, slopes, and ridgelines
3. Prevailing wind direction — draw a large arrow
4. Wind shadow zones — shade in the downwind area behind each obstacle (20x height)
5. Candidate sites — mark locations that are elevated, upwind of obstacles, and accessible
6. Wire run distances — measure or pace the distance from each candidate to your battery bank location

Compare candidates objectively. The best site is usually obvious once mapped — it is the highest, most exposed point with clear upwind fetch that is still reasonably close to where you live.

Tower Height Considerations

If your best accessible site has nearby obstacles, a taller tower can lift the turbine above the disturbed air zone. The turbine rotor should be at least 10 meters above any obstacle within 150 meters. Tower height is expensive in materials and labor, so a better site with a shorter tower almost always beats a poor site with a tall tower.

Community and Social Considerations

In a survival community, turbine siting involves more than wind.

• Noise — Small turbines produce a constant whooshing sound. Site at least 50 meters from sleeping areas, more if possible. Noise increases dramatically with wind speed.
• Safety zone — If a blade breaks, fragments can be thrown 50+ meters. Keep the area around the tower clear of structures and foot traffic.
• Visual impact — Some community members may object to a tall tower in their sightline. Address this early; the energy benefit usually wins the argument, but it helps to involve people in the decision.
• Shared access — If the turbine powers shared infrastructure (water pumping, grain milling, medical equipment), site it near that infrastructure rather than near any individual’s shelter.
• Redundancy — Do not put all turbines in one location. Spread them to reduce the impact of localized damage or calm spots.

Combining Wind with Other Energy Sources

Wind alone is unreliable. Calm periods lasting days or even weeks happen everywhere. A robust energy system combines multiple sources.

Source	Best Season	Best Conditions	Complements Wind?
Solar (photovoltaic)	Summer	Clear skies, long days	Yes — strongest when wind is weakest
Micro-hydro	Spring/rainy season	Flowing water year-round	Yes — often steady when wind and sun fail
Biomass/wood gas	Year-round	Stockpiled fuel	Yes — available on demand as backup
Human/animal power	Year-round	Labor available	Emergency backup only

Wind + Solar Is the Survivor's Best Combination

If you have access to salvaged solar panels, pair them with your wind turbine on the same battery bank. Summer sun covers the calm months; winter wind covers the dark months. This combination dramatically reduces the battery storage you need.

Common Mistakes

Mistake	Cause	Fix
Turbine placed in wind shadow	Underestimating how far obstacles affect wind (20x height)	Map all obstacles, calculate shadow zones, move site upwind
Site chosen for convenience, not wind	Putting turbine next to the house instead of on the hilltop	Accept the wire run cost; a good site is worth 50m of extra cable
Ignoring seasonal wind shifts	Assessing in windy month, building for year-round use	Observe for at least one full season before committing to a site
Tower too short	Trying to save materials on tower height	Ensure rotor is 10m above any obstacle within 150m
Building on the lee side of a ridge	Assuming the top of a slope equals the top of a ridge	Walk to the actual crest; lee-side turbulence extends far downwind
Not accounting for turbulence	Good average speed but chaotic, swirling wind	Check for deformation in nearby vegetation; look for consistent, steady flow

Key Takeaways

• Site selection matters more than turbine design — a mediocre turbine in great wind outperforms a perfect turbine in bad wind
• Place turbines at least 20x obstacle height downwind or 2x obstacle height above any upwind obstacle
• Use tree deformation, flag behavior, and erosion patterns to estimate long-term wind exposure without instruments
• Map your entire available area before choosing — mark obstacles, elevation, wind shadows, and candidate sites
• The ideal site is elevated, has 300+ meters of clear upwind fetch, and is reasonably close to your battery bank
• Plan for a taller tower if nearby obstacles cannot be avoided
• Combine wind with solar for year-round energy security — they complement each other seasonally