[RE-wrenches] Transmitting 15kW 3600ft Off Grid.

[Hilton Dier]

So you have a client with clever ideas - my deepest sympathies. The five most frightening words from a client are “I am a retired engineer.”

DC transmission is theoretically more efficient due to the surface conduction effects of AC. However, this is only true in a practical sense at utility/megawatt scale. At residential scale you will have losses in the electronics at either end that will negate the wire savings.

Get some toroidal transformers and go to 480 and back. Fat wire is kind of expensive, but really it’s the trench (and these days, pvc conduit) that cost the money. Fat wire in conduit is solid state and will never blow a capacitor. Transformers, if not overloaded, last. 

On that last point, 2x oversize the transformers for the load. There will be “mission creep” while you aren’t looking. “Oh, we didn’t think that half a dozen 1500 watt resistance heaters scattered around would make any difference.”

Good luck. 

Hilton Dier III
Renewable Energy Design
Missisquoi River Hydro LLC