SolarRoof owners - how do we monitor string production?

[jboy210]

Hi,

My production numbers are low and I wondering if one of the strings of tiles is not producing. Does anyone know how to verify this?

When I contacted Tesla they said there was no way to see individual strings from the square Tesla box. Do I need to go in the attic and somehow measure DC current flow from the strings?

 

[TSleuths]

Why not go into the attic and try to test the voltage or current with one of those clamp type multimeters?

Darwin Chaug with a V3 roof had an issue with excess dust causing low power production. He went from 45 kWh per day to 30. Then after pressure washing back up 50% to the full amount. It was only a month or two before they got dirty.

 

[jboy210]

Why not go into the attic and try to test the voltage or current with one of those clamp type multimeters?

Darwin Chaug with a V3 roof had an issue with excess dust causing low power production. He went from 45 kWh per day to 30. Then after pressure washing back up 50% to the full amount. It was only a month or two before they got dirty.

I will have to get clamp MM. My current MMs are 15+ years old bench sets and used only for small electronic circuits with milli-amps. Looks like I am off to Amazon to get some new toys!

We are having our roof washed Friday, so I hope we can get similar gains.

 

[BrettS]

There was a thread on here recently about using a drone with a thermal camera to check for solar production. It’s kind of counter intuitive (at least to me), but functional panels will be cooler than non functional panels because functional panels use some of the energy from the sun to produce power while it all turns into heat on non functional panels. But if you don’t already have a drone and/or thermal camera that might be an expensive proposition.

Going into the attic and using a clamp meter to measure DC current might be a possibility, but if you want to do this keep in mind that a lot of of the less expensive clamp meters measure AC current only. There are definitely some that measure DC current, so make sure the one you get/have supports DC current and is set to measure DC current. Also it’s worth noting that to measure current you need to isolate a single wire. You can’t just clamp the meter around a conduit that contains multiple wires as wires with the current flowing in opposite directions will cancel each other out. So you may need to find a junction and open it up so you can isolate a single wire. Obviously be careful doing this because there can be a lot of power flowing through those wires.

Finally, if you have multiple inverters then maybe you could compare the output of the inverters individually. Obviously they may not match exactly if there are different numbers of active tiles going to each inverter or tiles facing in different directions. But if you have one inverter operating at 70% of it’s capacity and another inverter operating at 30% of it’s capacity then I feel like there might be some reason for concern there.

 

[jboy210]

There was a thread on here recently about using a drone with a thermal camera to check for solar production. It’s kind of counter intuitive (at least to me), but functional panels will be cooler than non functional panels because functional panels use some of the energy from the sun to produce power while it all turns into heat on non functional panels. But if you don’t already have a drone and/or thermal camera that might be an expensive proposition.

Going into the attic and using a clamp meter to measure DC current might be a possibility, but if you want to do this keep in mind that a lot of of the less expensive clamp meters measure AC current only. There are definitely some that measure DC current, so make sure the one you get/have supports DC current and is set to measure DC current. Also it’s worth noting that to measure current you need to isolate a single wire. You can’t just clamp the meter around a conduit that contains multiple wires as wires with the current flowing in opposite directions will cancel each other out. So you may need to find a junction and open it up so you can isolate a single wire. Obviously be careful doing this because there can be a lot of power flowing through those wires.

Finally, if you have multiple inverters then maybe you could compare the output of the inverters individually. Obviously they may not match exactly if there are different numbers of active tiles going to each inverter or tiles facing in different directions. But if you have one inverter operating at 70% of it’s capacity and another inverter operating at 30% of it’s capacity then I feel like there might be some reason for concern there.

Thanks for passing along the issues with DC measurement. There is a junction box in the attic, so I assume the leads feed in there and then down to the inverter. I was going to take a look at it. Hopefully, there will just be some terminal lugs I check with a probe.

We have multiple inverters. One is 8Kw and the other is 4Kw. I believe the 8Kw is for the south-facing and one north-facing strang, and the 4 kW is for the other North facing. I have done the really basic test and shutting them off one-by-one. In both cases, there was a drop when I shut one down and restoration when I brought it back on-line. So I think that at least at that the basic level the inverters are working.

Did anyone get some sort of string to inverter wiring diagram from Tesla?

 

[BrettS]

Thanks for passing along the issues with DC measurement. There is a junction box in the attic, so I assume the leads feed in there and then down to the inverter. I was going to take a look at it. Hopefully, there will just be
some terminal lugs I check with a probe.

To measure current with a probe you need to break the circuit and have all of the power flow through the meter. So if there was a lug there you would need to disconnect it, then connect the wire to one probe and connect the other probe to the lug. With the amount of voltage and current that we are talking about, this is probably not something you want to be doing. Using a clamp on meter would be much safer and easier.

We have multiple inverters. One is 8Kw and the other is 4Kw. I believe the 8Kw is for the south-facing and one north-facing strang, and the 4 kW is for the other North facing. I have done the really basic test and shutting them off one-by-one. In both cases, there was a drop when I shut one down and restoration when I brought it back on-line. So I think that at least at that the basic level the inverters are working.

Do you have any way to see how much each inverter is generating? With a screen on the inverter or connecting your phone to it or anything?

I suppose you could still see how much each inverter is producing on a sunny day by shutting off the 4kW inverter. On a bright sunny day, note how much power you are producing before you shut off the inverter, then note how much it drops after it is shut off. That is the amount of power the 4kW inverter is producing. Then note how much power is being produced while the 4kW inverter is off. That’s how much the 8kW inverter is producing. If it looks like the 8kW inverter is producing 6 or 7kW and the 4kW inverter is producing 2.5 or 3kW then you’re probably good. If you’re only getting 3kW out of the 8kW inverter then that’s probably worth investigating further.

Actually, maybe the better place to start would be using an AC clamp meter to measure the AC current coming out of each inverter. Again, I would suggest doing this on a bright sunny day, but open your electrical panel and use the meter to measure the current from each inverter. Again, remember that you need to isolate a single wire, so pick the red or the black wire. That will give you the number of amps that the inverter is producing. Watts = volts times amps, so take that number, multiply it by 240V (or actually measure your voltage with your meter for a little more accuracy). Then divide it by 1000 to convert from watts to kilowatts. Again, if both inverters seem to be producing at about the same capacity, then you’re probably good. If one is producing at a significantly lower capacity than the other then you might want to keep investigating.

Did anyone get some sort of string to inverter wiring diagram from Tesla?

I don’t have a solar roof, but the electrical drawings submitted to my city for my permit did show which panels would be connected to which inverter in my case.

 

[wjgjr]

Did anyone get some sort of string to inverter wiring diagram from Tesla?

All I got was what was sent to the county (and hopefully I got all the terms correct.) It shows that on each roof face, I have 70 shingles, and each is split into two strings of 35 shingles. There are two "Pass through box, two string, reworked" boxes, one for each roof face, after which are "branch sockets" which combine the two strings from each roof face. Each of these then passes through a rapid disconnect device, and, according to the diagram, I then have two sets of DC wires - one for each roof face - running into our inverter. I have not tried to determine if anything in the inverter can distinguish the input from the two roof faces, but even at that point, it would be difficult to determine if there was a small issue with the number of shingles involved.

 

[GHall]

The Delta M Tool app or m tool professional app will show you individual string data. It is a Bluetooth app so you have to be fairly close to the unit to have it discovered. Use your inverter date code listed on the side of the unit as the unit code.

 

[wjgjr]

The Delta M Tool app or m tool professional app will show you individual string data. It is a Bluetooth app so you have to be fairly close to the unit to have it discovered. Use your inverter date code listed on the side of the unit as the unit code.

Unfortunately for me, the Solivia does not have that option - it does have a Zigbee module (which I think is custom for Tesla - the standard documentation just mentions RS485 and the option for a Solivia Gateway) but I have not tried to see if I can use it to access the data in the way SolarEdge users can (when Tesla is forwarding the data, anyway.) Looking at the display on the device, it does show that there are two strings but it only shows the current power in Watts or, for history, the maximum value for that time period. Production numbers are only reported for the inverter in total.

 

[jboy210]

The Delta M Tool app or m tool professional app will show you individual string data. It is a Bluetooth app so you have to be fairly close to the unit to have it discovered. Use your inverter date code listed on the side of the unit as the unit code.

I am trying to set this up but don't know how answer the questions it's is asking. Should I set this up as "commissioning"?

 

[GHall]

I am trying to set this up but don't know how answer the questions it's is asking. Should I set this up as "commissioning"?

If you use the “m tool” app (either ios or android) it should just find your device (inverter). Select the device, enter your date code (on the side of the inverter) and it should just display your inverters string voltages and overall power of the system.

 

[jboy210]

If you use the “m tool” app (either ios or android) it should just find your device (inverter). Select the device, enter your date code (on the side of the inverter) and it should just display your inverters string voltages and overall power of the system.

I don't see any 'm tool' in the Android play store. The application I installed is called MyDeltaSolar and is the top one on the list when I search for 'm tool' in the play store.

Once in this app I see my wifi networks, but no option for bluetooth.

 

[MXDogCrate]

This is a helpful conversation.

A portion of our crew is still here. If there’s a question I can ask that would be helpful to you, let me know.

 

[jboy210]

This is a helpful conversation.

A portion of our crew is still here. If there’s a question I can ask that would be helpful to you, let me know.

If you could find out how to directly monitor the power from the strings to your M series inverter that would be much appreciated. Our installers did not know how to do it.

 

[wjgjr]

If you could find out how to directly monitor the power from the strings to your M series inverter that would be much appreciated. Our installers did not know how to do it.

Just guessing, since I don't have an M series, but this may be the app that was mentioned:

https://play.google.com/store/apps/details?id=com.hdc.donnieli.mprofessional&hl=en_US&gl=US

 

[MXDogCrate]

From my lead (who was promoted to oversee multiple projects as he arrived on site, so I think he knows what he’s talking about):

“The powerwall Gateway does that but it doesn’t display individual strings just overall production . If you’ll like to see each individual string per inverter then you’ll need the M-professional app . It will send alert is an in error or strings aren’t working. If production is below what’s expected you’ll be able to tell with the overview on Tesla app .

The only way I know to check individual strings would be directly from the inverter.

M Professional by Jiang Tao Yan .
That’s the app we use . But you would have to be next to the inverter. It communicates using Bluetooth.”

Same as @wjgjr recommended above. It’s the one our team uses.