Build a DIY Wind Turbine From PVC Pipe and a Car Alternator

Step-by-step project guide for building a working wind turbine using PVC pipe blades, a repurposed car alternator, and basic hardware. Great for rural homesteads and off-grid remote power.

Project Overview: What You'll Build

This guide walks you through building a functional horizontal-axis wind turbine using:

• PVC pipe carved into airfoil blades
• A repurposed automobile alternator (converted to permanent magnet) or a purpose-built PMG
• Steel pipe and weld-on hub assembly
• Tail vane for automatic yaw control

Expected output: 200–400W in a 15–20 mph wind. Best for powering remote loads — a water pump, cabin lighting, or supplemental off-grid battery charging where grid power isn't available.

Blade Design: PVC Pipe Airfoils

PVC pressure pipe (Schedule 40 or 80) can be cut into surprisingly effective airfoil blade profiles:

1. Cut 4-inch PVC pipe into 4-foot sections (3 blades for a 8-foot rotor diameter)
2. Mark a blade template using the "Hugh Piggott blade profile" — freely available online and widely proven
3. Use an angle grinder or belt sander to shape the leading and trailing edges
4. Sand to 220 grit, paint with UV-resistant enamel
5. Balance blades by hanging from center and adding weight to light end

Blade material alternatives: carved hardwood (best aerodynamics, heavier), fiberglass/epoxy layup (best performance, most complex), or pre-made composite blades ($100–300 for a 3-blade set).

The Generator: Alternator Conversion vs PMG

Option A: Car alternator conversion

A standard car alternator can be converted to a permanent magnet generator by replacing the rotor's electromagnet with neodymium magnets. This is a well-documented modification but requires machining skills.

Advantages: cheap (free from salvage), familiar design. Disadvantages: requires internal modification, relatively low efficiency, needs to spin fast (requires gearing up for a direct-drive wind turbine).

Option B: Purpose-built PMG (Permanent Magnet Generator)

DIY axial flux generators using cast magnet rotors and wound stators are the approach used by most serious DIY wind builders. Hugh Piggott's designs (freely documented at scoraigwind.co.uk) are the gold standard — proven across thousands of installs worldwide.

Tower and Mounting

Even for a small project turbine, proper mounting is critical for safety and performance:

• Minimum tower height: 20 feet (more is better)
• Use galvanized steel pipe for the tower — 2" Schedule 40 pipe for small turbines
• Guy wire the tower in 3 directions at 60° spacing
• The turbine must be able to turn freely (yaw) to face the wind — a thrust bearing at the tower top enables this
• The tail vane automatically turns the turbine to face the wind direction

Electrical Connection to Battery Bank

The alternator/PMG output is 3-phase AC (for most designs), which must be rectified to DC before charging your batteries:

1. Connect 3-phase output to a 3-phase bridge rectifier (50A+ rating)
2. Connect rectified DC through a wind charge controller (prevents overcharge and dumps excess power to a dump load resistor)
3. Connect to 12V or 24V battery bank
4. Dump load: a resistive load (water heating element works well) absorbs excess power when batteries are full — without a dump load, the turbine can overspeed and destroy itself