Out of curiosity, for those so interested, I have measured the efficiency of some inverters at partial loading.
Tests were conducted with a CC-CV power supply of variable current limit, AC side was measured using a calibrated instrument.
Feel free to add your unit to the thread too!
Enphase IQ8M
Voltage was set at 25V. The input power includes voltage drop on the vables.
@ 250mA - About 2W
@ 500mA - About 12.5W
@ 750mA - About 19W
@ 1A - ABout 25W
@ 1.5A - About 37W
@ 2A - 44W, with an input power of 48W, giving an efficiency of 91%
@ 2.5A - 55W, with an input power of 60W, giving an efficiency of 91%
@ 3A - 65W with an input power of 70W, giving an efficiency of 92%
Discussion:
At 2A and above, the MPPT tracker tracks correctly over a narrow voltage range. Here the highest efficiency is observed. At over 90% with less than 50W input, the enphase behaves on the top of the inverters I tested and gives a good yeld under poor light conditions.
Below 2A the MPPT trackers fails to track correctly, hovering the whole range from 16V to 24V, hence the average figure provided. For example at an input of 1A, the worse situation happens with Vin = 16V with an output power of 14W. Output rises to 22W, when the input voltge is allowed to reach 22V.
The enphase has a very low operating current of about 0.3W, which means more of the power is converted to AC, and sooner.
Other remarks:
Time from cold boot to power injection: ~20Seconds
DC Voltage to start feeding: 22V
Minimun MPPT track voltage: 16V
The test scenario here is the lowest input voltage. efficiency is likelly to increase slightly at nominal input of 28-33VDC.
Bulky capacitors at the input.
My (new) units required the envoy-S for the original comissioning, required to enable output power injection.
Mastervolt Soladin 1000 (newer grey version)
Voltage was set at 90V. The operating current is 20mA, or ~2W. The device starts producing power once more than 5W is available on the DC side.
@ 0.018 - Input = 16.2W, Output 9.5W -> Efficiency = 57% - MPPT was unable to track and operated at minimun voltage of 72V
@ 0.26A - Input = 23W, Output 18W -> Efficiency = 78%
@ 0.5A - Input = 44.5W, Output = 38W -> Efficiency = 85%
@ 1A - Input = 89W, Output = 82W -> Efficiency = 92%
@ 2A - Input = 178W, Output = 165W -> Efficiency = 92%
@ 3A - Input = 267W, Output = 246W -> Efficiency = 92%
@ 4A - Input = 356W, Output = 329W -> Efficiency = 92%
@ 5A - Input = 445W, Output 410W -> Efficiency = 92%
Discussion:
Above 200mA, the MPPT tracker tracks correctly at exactly input voltage minus 1V (In our case 89V, but does so with other input voltages as well).
Below that it goes to the lowest possible value of 72V, which gives a slight efficiency penalty. Yet, It's impressive it can even work at only 2% of it's rated power!
Other remarks:
This inverter has one of the best MPPT trackers I've seen on a solar inverter, it tracks well, tracks fast and provides a great efficiency
This inverter has galvanic isolation with an HF transformer.
DC Voltage to start feeding: 87V
Minimun MPPT track voltage: 72V
Inverter has WiFi but cloud platform was discontinued, so works as a 'dumb inverter'
The test scenario here is the lowest input voltage. Efficiency is likelly to increase slightly at nominal input of 150VDC.
Bulky capacitors at the input.
I also have a ecoflow powerstream, but can't find my notes right now.
Tests were conducted with a CC-CV power supply of variable current limit, AC side was measured using a calibrated instrument.
Feel free to add your unit to the thread too!
Enphase IQ8M
Voltage was set at 25V. The input power includes voltage drop on the vables.
@ 250mA - About 2W
@ 500mA - About 12.5W
@ 750mA - About 19W
@ 1A - ABout 25W
@ 1.5A - About 37W
@ 2A - 44W, with an input power of 48W, giving an efficiency of 91%
@ 2.5A - 55W, with an input power of 60W, giving an efficiency of 91%
@ 3A - 65W with an input power of 70W, giving an efficiency of 92%
Discussion:
At 2A and above, the MPPT tracker tracks correctly over a narrow voltage range. Here the highest efficiency is observed. At over 90% with less than 50W input, the enphase behaves on the top of the inverters I tested and gives a good yeld under poor light conditions.
Below 2A the MPPT trackers fails to track correctly, hovering the whole range from 16V to 24V, hence the average figure provided. For example at an input of 1A, the worse situation happens with Vin = 16V with an output power of 14W. Output rises to 22W, when the input voltge is allowed to reach 22V.
The enphase has a very low operating current of about 0.3W, which means more of the power is converted to AC, and sooner.
Other remarks:
Time from cold boot to power injection: ~20Seconds
DC Voltage to start feeding: 22V
Minimun MPPT track voltage: 16V
The test scenario here is the lowest input voltage. efficiency is likelly to increase slightly at nominal input of 28-33VDC.
Bulky capacitors at the input.
My (new) units required the envoy-S for the original comissioning, required to enable output power injection.
Mastervolt Soladin 1000 (newer grey version)
Voltage was set at 90V. The operating current is 20mA, or ~2W. The device starts producing power once more than 5W is available on the DC side.
@ 0.018 - Input = 16.2W, Output 9.5W -> Efficiency = 57% - MPPT was unable to track and operated at minimun voltage of 72V
@ 0.26A - Input = 23W, Output 18W -> Efficiency = 78%
@ 0.5A - Input = 44.5W, Output = 38W -> Efficiency = 85%
@ 1A - Input = 89W, Output = 82W -> Efficiency = 92%
@ 2A - Input = 178W, Output = 165W -> Efficiency = 92%
@ 3A - Input = 267W, Output = 246W -> Efficiency = 92%
@ 4A - Input = 356W, Output = 329W -> Efficiency = 92%
@ 5A - Input = 445W, Output 410W -> Efficiency = 92%
Discussion:
Above 200mA, the MPPT tracker tracks correctly at exactly input voltage minus 1V (In our case 89V, but does so with other input voltages as well).
Below that it goes to the lowest possible value of 72V, which gives a slight efficiency penalty. Yet, It's impressive it can even work at only 2% of it's rated power!
Other remarks:
This inverter has one of the best MPPT trackers I've seen on a solar inverter, it tracks well, tracks fast and provides a great efficiency
This inverter has galvanic isolation with an HF transformer.
DC Voltage to start feeding: 87V
Minimun MPPT track voltage: 72V
Inverter has WiFi but cloud platform was discontinued, so works as a 'dumb inverter'
The test scenario here is the lowest input voltage. Efficiency is likelly to increase slightly at nominal input of 150VDC.
Bulky capacitors at the input.
I also have a ecoflow powerstream, but can't find my notes right now.
