testing grid tie inverters

ferg75407 · 10-25-19, 12:31 PM

As I was preparing to pull my solar off my roof to replace faulty shingles I noticed neither of my 2 solar arrays were producing. Checked breakers and fuses, checked voltage and current, all good except no current. Sunglasses off, the sun is up and no clouds. Recalled something about calling "the Guy" to reset the inverters, no I am "the guy". Turned off the breakers from the panels and called it a day.
Next morning flipped on the breakers and waited for the sun. The current and the sun came up together! I am "the guy"!.
Next day the sun came up but not the inverters. Tried the breaker thing again, tried thinking some more, flipped the breakers back on, still no current.
I still needed to get the panels off for the reroofing says the insurance guy.
So i need to troubleshoot the inverters and panels. I plan to use my golf cart (48 vdc) to test my inverters. My volt meter and a small heater to test the panels. The inverters are enphase m215 grid tie.
Anyone have suggestions for troubleshooting these components the bench?

where2 · 10-25-19, 11:30 PM

If you had them attached where an Enphase Envoy can hear them and the envoy could see the internet, then you just pick up the phone and talk to the folks at Enphase. That was all the troubleshooting I needed to do to get a replacement M215 when one of mine bit the dust.

My troubleshooting consists of: checking panel output voltage. If I have typical panel voltage >30v (DC), then I call Enphase and say: "I think your inverter is defective, check my Envoy"

If you're using the golf cart for testing, keep in mind a typical 60 cell panel runs 36V, and the M215 was never intended to be driven by a 72 cell panel which has 42V open circuit voltages.

ferg75407 · 10-26-19, 09:28 AM

Thanks, when the sun's not out, I'll skip one of the 8 vdc batteries to get 40 vdc. I looked up the envoy there was a m215 adapter for 170$ * 24 inverters + 600$ for the envoy = 4k$. Do i have to get these adapters? With the new roof hanging over my head in the immediate future I'll have to wait. Meanwhile I'm going to try it on the bench. How does one bad inverter shut down 2 arrays?

where2 · 10-30-19, 10:38 PM

Quote:

Originally Posted by ferg75407

How does one bad inverter shut down 2 arrays?

Have you priced a replacement M215? Get an M250 if you can't find the M215s.

One bad inverter won't shut down two arrays. One bad microinverter shuts down one panel. Explain how your multiple panels are tied into one M215 inverter?

I've got a 4.4kW system: twenty M215 inverters on the roof, twenty 220W panels, two different trunk cables wired to two different circuits with 10 inverters plugged into each trunk. (I do my own troubleshooting because I'm the guy who drew the 3-line diagram for my PV array, got my system permitted by the state agency that reviews PV systems, I pulled my local AHJ permits, and installed my own array. The only part I farmed out was the structural engineering calculations, because I'm not a P.E.).

ferg75407 · 10-31-19, 01:27 PM

I have 14 inverters and panels on one breaker and 10 each on another breaker both go to 1 disconnect.
I got everything off of the roof and have isolated one m215 that does not put out any current, but it does boot up correctly.
I found some m215 on ebay for 40-60$.
I do not understand why the one array would not come online. When go back up with the system I will install a few at a time, test, install more, test, etc.

where2 · 11-02-19, 12:42 AM

When plugging things back in, keep track of the arrow on the inverter plug and the arrow on the trunk cable connector. The arrows need to point at each other when you're making the plug connection. Check the electrical connections downstream of the trunk cable. The trunk cable should be live with 240V when the breakers are in the ON position. Probe with a voltmeter and see what you have. The L1 or L2 to N voltage is 120V, the trunk cable carries L1, L2, N, & G conductors. If I recall correctly, the trunk cable has the conductors for the plug labeled.

I would venture to guess the 14 inverter string is the string that stopped working. Why? Because 14 inverters one one trunk cable puts out around 14A peak, and day after day driving 14A through an electrical connection that isn't perfect will show the imperfections. Open the panels and boxes between the end of the trunk cable and the breaker panel this all feeds into, and you may find something charred and melted.

10-25-19, 12:31 PM	#1
ferg75407 Lurking Renovator Join Date: Oct 2012 Location: north texas Posts: 15 Thanks: 4 Thanked 1 Time in 1 Post	testing grid tie inverters As I was preparing to pull my solar off my roof to replace faulty shingles I noticed neither of my 2 solar arrays were producing. Checked breakers and fuses, checked voltage and current, all good except no current. Sunglasses off, the sun is up and no clouds. Recalled something about calling "the Guy" to reset the inverters, no I am "the guy". Turned off the breakers from the panels and called it a day. Next morning flipped on the breakers and waited for the sun. The current and the sun came up together! I am "the guy"!. Next day the sun came up but not the inverters. Tried the breaker thing again, tried thinking some more, flipped the breakers back on, still no current. I still needed to get the panels off for the reroofing says the insurance guy. So i need to troubleshoot the inverters and panels. I plan to use my golf cart (48 vdc) to test my inverters. My volt meter and a small heater to test the panels. The inverters are enphase m215 grid tie. Anyone have suggestions for troubleshooting these components the bench?

10-25-19, 11:30 PM	#2
where2 DIY Geek Join Date: Apr 2013 Location: Sunny Florida Posts: 401 Thanks: 74 Thanked 83 Times in 73 Posts	If you had them attached where an Enphase Envoy can hear them and the envoy could see the internet, then you just pick up the phone and talk to the folks at Enphase. That was all the troubleshooting I needed to do to get a replacement M215 when one of mine bit the dust. My troubleshooting consists of: checking panel output voltage. If I have typical panel voltage >30v (DC), then I call Enphase and say: "I think your inverter is defective, check my Envoy" If you're using the golf cart for testing, keep in mind a typical 60 cell panel runs 36V, and the M215 was never intended to be driven by a 72 cell panel which has 42V open circuit voltages.

10-26-19, 09:28 AM	#3
ferg75407 Lurking Renovator Join Date: Oct 2012 Location: north texas Posts: 15 Thanks: 4 Thanked 1 Time in 1 Post	Thanks, when the sun's not out, I'll skip one of the 8 vdc batteries to get 40 vdc. I looked up the envoy there was a m215 adapter for 170$ * 24 inverters + 600$ for the envoy = 4k$. Do i have to get these adapters? With the new roof hanging over my head in the immediate future I'll have to wait. Meanwhile I'm going to try it on the bench. How does one bad inverter shut down 2 arrays?

10-31-19, 01:27 PM	#5
ferg75407 Lurking Renovator Join Date: Oct 2012 Location: north texas Posts: 15 Thanks: 4 Thanked 1 Time in 1 Post	I have 14 inverters and panels on one breaker and 10 each on another breaker both go to 1 disconnect. I got everything off of the roof and have isolated one m215 that does not put out any current, but it does boot up correctly. I found some m215 on ebay for 40-60$. I do not understand why the one array would not come online. When go back up with the system I will install a few at a time, test, install more, test, etc.

11-02-19, 12:42 AM	#6
where2 DIY Geek Join Date: Apr 2013 Location: Sunny Florida Posts: 401 Thanks: 74 Thanked 83 Times in 73 Posts	When plugging things back in, keep track of the arrow on the inverter plug and the arrow on the trunk cable connector. The arrows need to point at each other when you're making the plug connection. Check the electrical connections downstream of the trunk cable. The trunk cable should be live with 240V when the breakers are in the ON position. Probe with a voltmeter and see what you have. The L1 or L2 to N voltage is 120V, the trunk cable carries L1, L2, N, & G conductors. If I recall correctly, the trunk cable has the conductors for the plug labeled. I would venture to guess the 14 inverter string is the string that stopped working. Why? Because 14 inverters one one trunk cable puts out around 14A peak, and day after day driving 14A through an electrical connection that isn't perfect will show the imperfections. Open the panels and boxes between the end of the trunk cable and the breaker panel this all feeds into, and you may find something charred and melted.