A wind turbine’s electrical system has five links in order: the alternator, a rectifier, a shunt charge controller that keeps the turbine loaded, a lead-acid battery bank, and an inverter for AC loads. Choose 24 V or 48 V instead of 12 V when the wire run is long, because current falls in proportion to voltage and cable loss falls with its square, so the loss in 60 m of 16 mm² copper at 2 kW is 112 W at 48 V against 1,792 W at 12 V.
Part of Advanced Wind Turbine
The electrical system turns the alternator’s variable output into steady power that stores in batteries and runs the loads, and keeps the turbine safe when the batteries are full.
Five Links, Each With A Job
| Link | Job | Page |
|---|---|---|
| Alternator | variable-frequency three-phase AC | Permanent Magnet Alternator |
| Rectifier | six diodes turn the AC to DC | Stator Winding (Coil Design) for its voltage |
| Shunt charge controller | stops overcharge by diverting power to a dump load | Charge Controller |
| Battery bank | stores energy for calm periods | Battery Bank Sizing |
| Inverter | DC to AC for ordinary appliances | Inverter & Load Management |
Beside them sit the dump load and the overspeed protection (Dump Load & Overspeed Protection). The rule that ties the chain together is in the Charge Controller page: a wind turbine must never be disconnected from all load, since it will accelerate to destructive speed, so the controller is a shunt type. The lead-acid bank is the most available storage (Lead-Acid Construction).
Why The Bank Is 24 V Or 48 V
The carrier says 24 V or 48 V systems are more efficient than 12 V for longer wire runs. The reason is arithmetic. Current = power ÷ voltage, and the power lost in a wire is I² × R. Take a 2 kW turbine and 60 m of copper conductor (30 m out and 30 m back) of 16 mm². With a copper resistivity of 0.0172 Ω·mm²/m (a recalled handbook value), R = 0.0172 × 60 ÷ 16 = 0.0645 Ω.
| Bank voltage | Current at 2 kW | Voltage drop (I × R) | Power lost (I² × R) |
|---|---|---|---|
| 12 V | 167 A | 10.8 V | 1,792 W |
| 24 V | 83 A | 5.4 V | 448 W |
| 48 V | 41.7 A | 2.7 V | 112 W |
Going from 12 V to 48 V is four times the voltage and 4² = 16 times less loss. At 12 V the drop is nearly the whole supply, so the plant could not deliver its power through that cable at all. A thicker cable cuts the loss only in proportion to its area, but a higher voltage cuts it with the square. Where the batteries sit at the tower base, a 12 V bank with short leads is workable for a small turbine; see Conductor Selection.
What Wind Needs That Hydro Does Not
Variable source, stored energy
A hydro plant makes steady power, so the battery only covers peaks, and the dump load holds the speed (Battery Charging vs Direct AC). A wind turbine’s power changes hour by hour and falls to nothing in a calm, so the bank must be big enough to carry the village through several still days. The dump load protects the batteries and loads the turbine, rather than holding a steady speed.
Method: Wire It In Order
- Mount the rectifier at the tower base, near the controller; keep the three-phase run from the alternator to it short and heavy.
- Fuse each positive lead at the battery, with a disconnect switch.
- Connect the controller between rectifier and bank, with the dump load on the controller’s output.
- Connect the inverter directly to the bank through its own fuse, not through the controller.
- Test with the turbine tied off, using a bench supply or a hand drill on the alternator, before it spins in wind.
Common Mistakes
- 12 V with a long run — the cable burns the power.
- A series controller — it disconnects the turbine and lets it overspeed.
- Loads wired straight to the turbine — the output voltage swings with the wind.
Safety
A battery bank is a short-circuit machine
A lead-acid bank can deliver hundreds of amps into a short, enough to melt a wrench and start a fire. Fuse every positive lead close to the battery, insulate terminals, and ventilate: charging releases hydrogen, which is explosive (Charge Controller). The inverter’s AC output at 120 V or 230 V is lethal (Electrical Safety). Apply the rotor brake and lower or furl the turbine before touching any wiring.
What’s Next
- Learn next: Battery Bank Sizing for how much storage
- Combine with: Dump Load & Overspeed Protection