Inverter First Power on Checklist

[sabo]

I am looking for a checklist to review prior to flipping the switch on my Solar Disconnect Switch for the first time. I am looking to check my work so I can see if I am making any mistakes that may cause damage to my inverter. I searched the forum and on Google but only found this:

Off Grid Checklist

My system is battery less and currently no AC input or output connected yet.
Any suggestions or recommendations?

Thanks

 

[Mattb4]

Without knowing your setup other than no battery or grid AC in /out. It is hard to give advice.

Your manual should tell you the correct sequence for provisioning your system. The sequence from your link is a good overview of the subject but your manual takes precedence.

 

[Rednecktek]

The instruction sheet for my camp lists:

Step 1: Turn on battery breaker
Step 2: Press and hold precharge button for 10sec
Step 3: Turn on inverter switch
Step 4: Turn on PV breaker

 

[Hedges]

Polarity and voltage. Check with DMM.
Confirm voltage is what was expected, and within inverter limits.
Make sure you calculated PV panels Voc for cold weather and that also is within limits - otherwise it might operated until winter, then die.

Batteryless, you say. So Red Neck's precharge instructions don't apply (they are most important for lithium.)

Connect ground wire solar panel frames back to the system, and ground that to earth. People get AC shocks from undamaged systems, can get DC shocks if there is damage.

 

[sabo]

I am also wondering about any gotchas for which I may be unaware.

Example:

MC4 Connectors. We name MC4 connectors by the housing, not by the contact sheet, this is because the contact sheet of a male MC4 is female and the contact sheet of a female MC4 is male. BE VERY CAREFUL NOT TO CONFUSE THEM.

 

[Rednecktek]

I am also wondering about any gotchas for which I may be unaware.

Example:

MC4 Connectors. We name MC4 connectors by the housing, not by the contact sheet, this is because the contact sheet of a male MC4 is female and the contact sheet of a female MC4 is male. BE VERY CAREFUL NOT TO CONFUSE THEM.

I screw that up all the time trying to remember the skinny peg goes in the fat housing and vise versa. ?

 

[sabo]

I screw that up all the time trying to remember the skinny peg goes in the fat housing and vise versa. ?

Now I am trying to figure out If or how this matters because hot will be hot all the way from the panels to the inverter but my cable colors may not be the same color all the way from the panel to the inverter.

 

[sabo]

Polarity and voltage. Check with DMM.
Confirm voltage is what was expected, and within inverter limits.
Make sure you calculated PV panels Voc for cold weather and that also is within limits - otherwise it might operated until winter, then die.

Batteryless, you say. So Red Neck's precharge instructions don't apply (they are most important for lithium.)

Connect ground wire solar panel frames back to the system, and ground that to earth. People get AC shocks from undamaged systems, can get DC shocks if there is damage.

Good to know, I thought I only had to ground to a ground rod near the panel mount.

 

[Hedges]

I use colors for wire in conduit from inverter to junction box. Just black PV wire with MC3/4 connectors outside that.
Double-check polarity before closing switch to inverter (some but maybe not all have diode to clamp reverse polarity.)

When connecting MC connectors to something not visibly open-circuit, I use DMM to ensure it is open. Voltage starts out showing but decays as capacitance charges. If actually connecting to a short or parallel to a string of different voltage, DMM shows steady voltage.

As soon as you stick a DMM probe inside the touch-safe MC connector, you've got a non-touch-safe pin offering exposed hazardous voltage. Make or buy un-keyed MC to shrouded banana test leads?

 

[Hedges]

Good to know, I thought I only had to ground to a ground rod near the panel mount.

Definitely not. If short from PV+ to frame, even grounding frame with a (25 ohm connection to earth) ground rod, you could get a shock. And earthworms will be annoyed.

Usually, ground wire lets a fuse/breaker trip. Generally not with PV, but it pulls voltage low. Ground wire ampacity should be 1.56x array ISC, as should current-carrying home-run conductor.

You'll find tales here of people being shocked by unconnected PV terminals of inverter, by panel frames, a dog who didn't like to climb steps of RV.

DC isn't as dangerous as AC (I recently had a close call at work), but if you have high voltage strings it is still a hazard.

 

[Hedges]

"20 250w San Tan used panels"
Trina, I think.
At one point, Trina had leakage to frames and did a recall. I would think they would not let recalled panels reach the market, but all the more reason to ground frames.

"30.3 * 9 = 272 Volts"
Not "SELV" safe extra low voltage!

Proper grounding per NEC, a panel can be removed while maintaining ground to others. Either a clip that screws onto ground wire and has star washer to bite through oxide in aluminum PV panel frame, or something like WEEB hardware that bites between frame and rails.

 

[sabo]

"20 250w San Tan used panels"
Trina, I think.
At one point, Trina had leakage to frames and did a recall. I would think they would not let recalled panels reach the market, but all the more reason to ground frames.

"30.3 * 9 = 272 Volts"
Not "SELV" safe extra low voltage!

Proper grounding per NEC, a panel can be removed while maintaining ground to others. Either a clip that screws onto ground wire and has star washer to bite through oxide in aluminum PV panel frame, or something like WEEB hardware that bites between frame and rails.

Yes Trina

 

[sabo]

 

[sabo]

View attachment 146208

The clips I purchased dont look like the type you are recommending.

 

[Rednecktek]

Now I am trying to figure out If or how this matters because hot will be hot all the way from the panels to the inverter but my cable colors may not be the same color all the way from the panel to the inverter.

It matters when you forget which wire is which and get the wrong end on a wire and now you've got the wrong polarity.

Or you end up with 3 males and 1 female and the relationship lists as "Complicated". ?

 

[sabo]

I use colors for wire in conduit from inverter to junction box. Just black PV wire with MC3/4 connectors outside that.
Double-check polarity before closing switch to inverter (some but maybe not all have diode to clamp reverse polarity.)

When connecting MC connectors to something not visibly open-circuit, I use DMM to ensure it is open. Voltage starts out showing but decays as capacitance charges. If actually connecting to a short or parallel to a string of different voltage, DMM shows steady voltage.

As soon as you stick a DMM probe inside the touch-safe MC connector, you've got a non-touch-safe pin offering exposed hazardous voltage. Make or buy un-keyed MC to shrouded banana test leads?

Can you link to an example of "un-keyed MC to shrouded banana test leads" I googled but am not sure if the results are truly what I searched for. I had a hard time getting the small pins on my multimeter to stay in contact with the inside of the MC4 connector.

Mutli Meter

 

[Hedges]

MC4 banana test leads

Amazon.com

Pomona PVLEAD1 MC4 to 4 mm Test Lead Set

Pomona PVLEAD1 MC4 to 4 mm Test Lead Set

www.ktool.net

I should buy myself a set before I succeed in killing myself more thoroughly.
I even have some sort of an Amazon coupon from work, enough to buy those inexpensive ones.

Both of those appear to have latches on MC4. Maybe not a big deal with the tool (I'm still using my fingers), or could be cut off.

I like that the male banana in Amazon picture has plastic tip. I've got some others I'm using everywhere (cost $40 for kit of 70 stackable banana, 5 colors) and what I don't like is that exposed metal end is only recessed a couple mm. I think I could come in contact if not careful.

 

[Hedges]

Mutli Meter

At $19, a very low cost DMM.

Cheap meters aren't recommended for working on line voltages (because they don't have a fuse good enough to interrupt fault currents), but since this one is clamp current only, maybe not such a problem. Most of us have Fluke, maybe others.

That meter is AC amps only. You may find clamp DC handy. I selected Harbor Freight Ames 1000A meter because it can read inverter battery current, automotive starting current, also PV strings with 0.01A resolution. Most of the meters, including most Fluke, only have 0.1A resolution.

Batteries died this morning?

A battery voltage under 12 Volt is almost empty. So you’re definitely drawing more power than you think. The battery heaters should not be active at 48° F. Q1. Are the heaters active? Q2. How much wattage are these heaters? When I checked them yesterday at those temps they were not. They are...

diysolarforum.com

 

[sabo]

At $19, a very low cost DMM.

Cheap meters aren't recommended for working on line voltages (because they don't have a fuse good enough to interrupt fault currents), but since this one is clamp current only, maybe not such a problem. Most of us have Fluke, maybe others.

That meter is AC amps only. You may find clamp DC handy. I selected Harbor Freight Ames 1000A meter because it can read inverter battery current, automotive starting current, also PV strings with 0.01A resolution. Most of the meters, including most Fluke, only have 0.1A resolution.

Batteries died this morning?

A battery voltage under 12 Volt is almost empty. So you’re definitely drawing more power than you think. The battery heaters should not be active at 48° F. Q1. Are the heaters active? Q2. How much wattage are these heaters? When I checked them yesterday at those temps they were not. They are...

diysolarforum.com

Thanks for the recommendation I think I will pick one up.

CM1000A 1000A T-RMS AC/DC Clamp Meter

Amazing deals on this 1000A T-Rms Ac/Dc Clamp Meter at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[sabo]

Polarity and voltage. Check with DMM.
Confirm voltage is what was expected, and within inverter limits.
Make sure you calculated PV panels Voc for cold weather and that also is within limits - otherwise it might operated until winter, then die.

Batteryless, you say. So Red Neck's precharge instructions don't apply (they are most important for lithium.)

Connect ground wire solar panel frames back to the system, and ground that to earth. People get AC shocks from undamaged systems, can get DC shocks if there is damage.

The ground wire coming into the System from the panels, what should that be grounded upon? The Subpanel attached to the inverter output?