How to Build a Small Scale Wind Turbine at Home

How to Build a Small Scale Wind Turbine at Home

Introduction

Building a small scale wind turbine at home can be a fun and rewarding project. As energy costs continue to rise, generating your own clean, renewable electricity is an attractive option. In this comprehensive guide, I will walk through all the key steps involved in designing, sourcing components, and constructing a homemade wind turbine from start to finish.

Benefits of Building Your Own Wind Turbine

There are several advantages to building your own small wind turbine:

  • Lower electricity bills – Any electricity generated can offset your consumption from the grid, reducing your utility bills.

  • Energy independence – Producing your own power gives you greater energy security and reduces reliance on the grid.

  • Eco-friendly – Wind energy produces no greenhouse gas emissions, unlike fossil fuel power plants.

  • Educational – You can learn a lot about renewable energy and electricity generation through hands-on experience.

  • Customization – You can tailor the turbine design to perfectly match your requirements and site conditions.

Key Components of a Wind Turbine

The main components of a wind turbine are:

Rotor Blades

  • The rotor blades capture the kinetic energy of the wind and convert it into rotational motion to spin the generator.

  • Most DIY designs use three rotor blades made of lightweight materials like wood, PVC, fiberglass, or carbon fiber. The optimal blade shape is an airfoil like an airplane wing.

Generator

  • The spinning rotor turns an internal generator to produce electricity.

  • Small wind turbines use direct current (DC) generators or permanent magnet alternators.

Tower

  • The tower supports the rotor up high where wind speeds are greater.

  • For small turbines, a tilt-up monopole or guyed lattice is common. Height is a key factor – turbines should clear any obstacles.

Controllers

  • A charge controller regulates the turbine’s output to safely charge batteries.

  • An inverter converts the DC electricity from the turbine into alternating current (AC) used by appliances and the grid.

Batteries

  • Batteries store excess power generated for use when the wind is not blowing. Deep cycle lead-acid batteries work well for wind systems.

Calculating Power Requirements

Before selecting components, you need to estimate your power requirements:

  • Take note of all electrical loads you wish to power like lights, appliances, well pump, etc. and calculate total wattage.

  • Estimate average hours of use per day for each appliance to determine total kilowatt-hours (kWh) per day required.

  • Remember to account for future energy needs too.

As a rule of thumb, small wind turbines can realistically provide 20-40% of electricity needs for a home.

Turbine Design Considerations

Here are some key factors to consider when designing your wind turbine:

Rotor Diameter

  • The rotor diameter largely determines the turbine’s power generation at a given wind speed.

  • For a small turbine, 8-10 feet diameter rotors are common.

Start-up Wind Speed

  • The cut-in speed is the minimum wind speed required for the turbine to start spinning and generating power. A lower cut-in speed is preferable.

Rated Power

  • The turbine’s rated power is its maximum power output at optimal wind speed, usually around 30 mph. For a home, 1-10kW is typical.

Survival Wind Speed

  • The survival speed is the maximum wind the turbine can withstand before components will become damaged. Aim for at least 100 mph.

Match Location Wind Profile

  • Select a turbine optimized for the average wind speeds and patterns at your specific location. Mismatching reduces performance.

DIY Rotor Blade Design

For first-time homebuilders, the easiest option is buying prefab blades. But you can make your own with these DIY approaches:

PVC Blades

  • Make a wooden template of your desired airfoil shape.

  • Use the template to cut blades out of PVC pipe sections.

  • Sand and shape the PVC carefully to achieve an aerofoil curve.

Wooden Blades

  • Cut blades out of wood boards using a jigsaw.

  • Shape and carve them to an airfoil profile. Apply fiberglass over the wood for protection and rigidity.

3D Printed Blades

  • Model your custom blades in CAD software.

  • Use a large 3D printer or 3D printing service to print blades in sections and bond together.

Carbon Fiber Blades

  • Lay up carbon fiber cloth over a foam mold in your airfoil shape.

  • Apply epoxy resin and vacuum bag to cure. Trim and finish mold edges.

Sourcing a Generator

You have two main options for the generator:

Car Alternator

  • A car alternator readily converts rotational force into electricity.

  • They are inexpensive and widely available but require appropriate windings and rectifier circuits.

Permanent Magnet Alternator

  • PMAs optimize power output from low rotor speeds.

  • More expensive but purpose-built for wind turbines. Come with built-in rectifiers.

When choosing, match the alternator size and rating to your rotor diameter and targeted power output.

Designing the Tower

The tower elevates the turbine high in the air:

  • For maximum wind exposure, total tower height should be 20-30 feet above surrounding obstacles.

  • Consider a tilt-up monopole tower – easy DIY construction and maintenance. Tilts down for blade repairs.

  • Alternatively a guyed lattice tower provides more height. Requires proper guy wire installation.

  • Ensure the tower has a strong enough load capacity to hold the turbine securely in storm winds.

Charge Controller Selection

The charge controller is a crucial component:

  • It regulates voltage and current from the turbine to safely charge your batteries without overcharging.

  • Preventing overcharging prolongs battery lifespan.

  • Match charge controller to your turbine’s output and battery bank size.

  • MPPT charge controllers are most efficient for small wind applications.

Inverter Sizing

Choosing the proper inverter depends on your loads:

  • The inverter must be sized adequately to handle the total watts of all AC appliances it will power.

  • Also consider surge wattage required when starting motors on appliances like refrigerators.

  • For grid-tied systems, the inverter must synchronize output with grid power.

  • An efficient pure sine wave inverter is the best choice.

Battery Bank Considerations

Batteries enable power storage:

  • To determine the battery bank size needed, consider days of autonomy desired and depth of discharge.

  • More battery capacity means longer periods of power when wind production is low.

  • Lead-acid batteries are most cost effective. Use deep cycle batteries.

  • Space batteries close together and keep connections short to minimize losses.

Safety Precautions

Take these essential safety steps:

  • Establish a clearance zone around the turbine to prevent blade strikes. Mark with high visibility markers.

  • Install a well-grounded lightning protection system for the turbine and batteries.

  • Have an automatic braking overspeed control to protect in high winds.

  • Use full guy wire tensioner assemblies on any guyed towers.

  • Sign and mark electrical panels clearly. Use fuses or breakers appropriately.

Testing and Troubleshooting

After completing turbine installation:

  • Verify all electrical connections are correct and secure before testing.

  • Start turbine rotation manually and check output voltages and currents. Address any issues.

  • If the turbine fails to start in normal winds, adjust blade pitch or governor settings as needed.

  • Check guy wires and bolts regularly in the first months for any loosening under loading. Tighten as required.

  • Fine tune components to maximize performance over the first year of operation.

Conclusion

Constructing your own small wind turbine at home is an involved but achievable project with proper planning and preparation. Following the guidelines provided here about component selection, tower configurations, safety protocols, and testing procedures will help ensure you are able to build an effective and long-lasting renewable energy system customized to your needs and location. With some patience and hard work, you will have the satisfaction of generating your own homegrown wind power.