Bench testing Enphase microinverters

jjackstone · 11-08-18, 05:00 PM

Checked the search engine and didn't see a thread for this. Has anyone here figured out a simple way to bench test microinverters? I'm sure a battery or power supply could be connected as a DC input, but from what I understand, there must be a line signal too or they won't work at all. Any ideas on how to simulate an ac signal with enough amplitude to activate the inverter? I would guess it also checks for line frequency. Also as far as I know all the Enphase inverters are 240 volts AC output so that might have to be taken into account.
JJ

where2 · 11-08-18, 08:58 PM

For the grid side, Set yourself up a 240V outlet. They don't seem to care if its an officially inspected 240V circuit, or just a temporary attachment point for testing purposes. An L14-20R outlet attached to the grid with an L14-20P on the end of a piece of trunk cable will do the trick. Just terminate the loose end of trunk cable with an appropriate insulating cover on the four wires. (it doesn't have to be a branch terminator, four wire nuts will work nicely, for testing purposes)

At that point, push 16-30V DC in the input leads on the inverter (minding the polarity designations) and see what happens after your grid connection to the inverter has been stable for 300 seconds or more. With input power (i.e. a solar panel), you should be able to see a slight up tick on current leaving the L14-20R, if the inverter is working properly.

You are correct, they look for voltage in specified range + frequency in range for >300 seconds before they will presume the grid is stable enough to add power to.

11-08-18, 05:00 PM	#1
jjackstone Helper EcoRenovator Join Date: Mar 2009 Location: Sacramento,Ca Posts: 88 Thanks: 5 Thanked 32 Times in 23 Posts	Bench testing Enphase microinverters Checked the search engine and didn't see a thread for this. Has anyone here figured out a simple way to bench test microinverters? I'm sure a battery or power supply could be connected as a DC input, but from what I understand, there must be a line signal too or they won't work at all. Any ideas on how to simulate an ac signal with enough amplitude to activate the inverter? I would guess it also checks for line frequency. Also as far as I know all the Enphase inverters are 240 volts AC output so that might have to be taken into account. JJ

11-08-18, 08:58 PM	#2
where2 DIY Geek Join Date: Apr 2013 Location: Sunny Florida Posts: 401 Thanks: 74 Thanked 83 Times in 73 Posts	For the grid side, Set yourself up a 240V outlet. They don't seem to care if its an officially inspected 240V circuit, or just a temporary attachment point for testing purposes. An L14-20R outlet attached to the grid with an L14-20P on the end of a piece of trunk cable will do the trick. Just terminate the loose end of trunk cable with an appropriate insulating cover on the four wires. (it doesn't have to be a branch terminator, four wire nuts will work nicely, for testing purposes) At that point, push 16-30V DC in the input leads on the inverter (minding the polarity designations) and see what happens after your grid connection to the inverter has been stable for 300 seconds or more. With input power (i.e. a solar panel), you should be able to see a slight up tick on current leaving the L14-20R, if the inverter is working properly. You are correct, they look for voltage in specified range + frequency in range for >300 seconds before they will presume the grid is stable enough to add power to.