Tower Styles Assuming you have made the decision to install a wind system, you are now ready to decide what tower style is best suited for your site and budget. Simply put you have three options in styles: 1. Self Support – Freestanding, Fixed 2. Guyed – Tilt up, Fixed 3. Monopole – Tilt up, Fixed

Free Standing / Self Support - Steel Design Differences

• Solid Rod • Hollow Tube or Hollow Rod • Angular

Solid Rod - ADVANTAGES

• Lower drag coefficient for wind & ice loading
  
• Factory welded lowers in field installation time
  
• Eliminates potential for rust from the inside out
  
• Highest corrosion resistance
  
• Less manpower needed to erect sections on site
  
• Require less base width due to being built solid

Solid Rod - DISADVANTAGES

• Most expensive form of fabrication
• Heavy in weight = Added shipping cost and crane or forklift for unloading on site
• Transported in large sections = additional shipping cost for oversize permits & wide load escorts

Freestanding / Self Support - Hollow Rod / Hollow Tube Design

ADVANTAGES

• Lower drag coefficient for wind & ice loading
• Most efficient engineering use of round steel
• Usually shipped in small sections = less transportation cost
• Lighter in weight than solid rod

DISADVANTAGES

• Tower leg weep holes plug up & hold moisture causing corrosion from the inside
• Moisture build up inside the leg can cause leg to split when freezing
• Many hollow rod towers are field assembled increasing man hours for assembly
• Flaws in manufacture inventory of the number of parts to be shipped can cause construction delays
• Requires larger base width due to Hollow leg design

Freestanding / Self Support - Angular Design

ADVANTAGES

• Most Economical form of manufacture
• Parts are light and compact = less expensive to ship

DISADVANTAGES

• Flat surface allows greater ice buildup
• Most labor intensive to build = more man power and hours on site
• Additional maintenance to check and tighten loose bolts
• Flaws in manufacture inventory of the number of parts to be shipped can cause construction delays
• Requires larger base width for added support

Free standing / Self Support Tower

ADVANTAGES

• (Small footprint) less land clearing is necessary
  Adaptable to uneven terrain
• No guy wires
• Safest installation (crane)
• Less vulnerable to damage than a guy tower
• Less man power / labor cost for installation
• Simplest foundation design
• Aesthetically speaking most people prefer to look at a self support tower

DISADVANTAGES

• Will cost 1/3 to 1/2 more than other tower types
• Must climb to service/maintain generator
• Crane cost for installation

Tilt - Up Tower

ADVANTAGES

• No Climbing
• Maintenance done on the ground
• Medium cost
• Pipe locally available
• Guy wires blend into their surroundings and visually disappear in a short distance

DISADVANTAGES

• Large Footprint
• Four Sets of guy wires
• Need relatively level terrain
• Cannot climb for minor work or simple inspections
• Takes longer to assemble
• Additional manpower needed to tilt up or down

Calculating ground Space needed for a Tilt up Tower ( 35 – 60% of total tower height + 15-20 feet for anchor shaft construction area). Additional space may be needed for tractor to winch tower up & down (3 x tower height)

Fixed Guyed Tower

ADVANTAGES

• Requires less open space than tilt up
• Lowest cost Tower
• Uneven terrain ok
• Guy wires blend into the surroundings and visually disappear from a short distance
• Width of sections smaller - falls under standard shipping rates

DISADVANTAGES

• Three sets of guy wires to protect
• Must climb to service or maintain generator
• Crane or gin pole cost to install
• More man hours for installation
• Calculation for radius of guy wires 80% of tower height + 15 – 20 feet for anchor shaft construction

MONOPOLE TOWER

• Typically used for large scale wind turbines
• Only a few small wind turbine manufactures offer a monopole design
• Available in tilt up or fixed design

ADVANTAGES

• Least expensive tower type
• Requires small area of land ( for fixed )
• Lightweight for installation and shipping
• Less manpower needed for installation

DISADVANTAGES

• Require climbing to service generator (unless tilt up)
• Requires larger / deeper foundation = more concrete / rebar
• Crane expense to install

What style of tower you use for your wind system is usually determined by the amount of land space and money you have available. Many manufactures sell tower’s designed for their systems in all styles to fit your available space and budget. You will find most manufactures have packaged deals available to buy the wind system and tower together. Some will offer a discount when purchasing both. It is not unusual for a tower to cost more than a wind system. All style towers require at a minimum, annual inspection of all tower related components, Bolts, cables, foundations, etc. etc. etc.

Additional tower style information in easy to print PDF

• Tower Styles
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