Off Grid Inverter Power Consumption & Efficiency

Author Message
nickskethisniks
Guru

Joined: 17/10/2017
Location: Belgium
Posts: 444
 Posted: 09:56pm 26 Jan 2023

Aaron, I did some rough testing on my ozz inverter a few weeks ago, this were the numbers I noted, testing was done with especially resistive loads:
I had 4 meters at hand, 3 uni-T true RMS meters (current clamp type) and 1 extech true rms voltage meter.

The AC meter is a chinese front panel meter and is actually accurate.

Measurement 1:
on my AC meter 328W
with my clamp meter:
2.2A 237VAC --> 521.4VA
8.0A 52.1V --> 417W

With this power level there is a substantial part reactive power I guess, all switched power supplies with a bad power factor so it seems?

328/417W -->78%

Measurement 2:
on my AC meter 1335W

with my clamp meter:
5.92A 238VAC --> 1409VA
28.3A 51.85VDC --> 1468W

1335/1468 => 90.9%

Measurement 3
on my AC meter 2340W
on my clamp meter:
10A 239.5VAC -->  2395VA
48.6A 51.3VDC --> 2493.18W

2340/2493 => 93.8%

Measurement 4

On my AC meter 3765W
with my clamp meter:
15.8A 238.8V AC --> 3773VA
82.2A 49.7V --> 4085W
3765/4085 =>92.2%

Measurement 5:

on my AC meter 6122W
with my clamp meter
27.2A 224V AC --> 6160VA
142A 48.5V --> 6887W
6122/6887 => 89%

My inverter is completely powering my house, so it's a real life example.
I have some difficulties how I best calculate the efficiency of the inverter because of the reactive power involved. But I did with the worsted scenario. But either way it looks like my inverter has the highest efficiency around the 2500W mark.

The dropping of the voltage with higher loads has to do with the long cable run between inverter and battery. To be improved.
I don't think I can improve more, just maybe the filter inductor between H-bridge and transformer, it gets hot, it only has 30mm˛ wire I think