High Voltage DC power Transmission Test

I decided to experimentally verify the work done by Bob WB4APR regarding his 330 Volt DC power distribution system HERE. He is using a single wire with an earth return, which I am interested in but used direct wires in my tests and then later used resistors to simulate longer wires. Below is my setup. I had a 400 watt 12v to 120v inverter and a Dell laptop power supply. I constructed the AC to DC doubler using a 470 uF and 560 uF 450 volt electrolytic capacitors, along with the 1kv diodes like Bob used in his write up.

I first connected the doubler directly to the Dell laptop power supply and verified that it worked, then I placed two 120 ohm resistors (one on the positive and the other on the return side) in the line feeding the power supply. The power supply provided a constant 19 volts regards of the line resistance. Note: you need to use a power supply with the 100-240 V AC rating. It turns out they will run on DC as well. 330 VDC is the peak voltage of 240 VAC.

I was then curious as to the efficiency of this power conversion system since it is stepping it up from 12 volts DC to 120 volts AC then doubling it to 330 volts DC, then sending it over the line to the laptop power supply and finally stepping it down to 19 volts DC.

I loaded the laptop power supply with a 25 ohm resistor which pulled about .76 amps. This is about 14 watts delivered to the load. I then took the measurements at the inverter end. It was consuming about 26 watts. So this is only about 55% efficient. I am losing almost half of my power in the conversion! Since I had the resistors in-line I figured there was loss there so I removed and remeasured. That only improved it by about 2-3 %, which is good in terms of what just the line loses are but the conversion efficiency seems low. I then thought that I needed to load the power supply heavier to get better efficiency, so I lowered the load resistor and was able to pull over 1.5 amps and the efficiency did go up to about 70%.

My conclusion is that this methods is usable and that since I was using clip leads even on the low voltage high current side and long leads for measuring current and voltage my calculations could be off a bit. I was hoping to see 80-90%  in terms of efficiency, however this is not bad when considering you can transmit this power over a 1 km distance with tiny 20 gauge wire. My intention is to use this method in a distributed generation, multi-node power system for field ham radio use like on field day, etc. I will post more details on this idea soon.