Does Tesla cap solar production in self consumption mode

[Kilotango74]

So recently had system installed. 12.25 with a powerwall and a powerwall +. The system gets to exactly 7.7kwh every day at peak production but goes no further. I know the system is not expected to produce 12.25, but to go to 7.7 everyday and no further is weird. I also understand that in self consumption after the powerwalls fill up production is reduced since i cannot push to the grid yet. This makes me feel the the solar production itself is being capped. Thoughts?

 

[SilverSp33d3r]

One powerwall + inverter? Or the powerwall + and a separate inverter? If it’s just the powerwall+ inverter the output max is 7.8 so your theoretically clipping at that point. Can you show your graph?

 

[arnolddeleon]

I sounds like you don't permission to operate (PTO) yet? If so then Tesla is probably capping production to prevent exporting power. Basically if you are not allowed to send to the grid and the Powerwalls are full there is no place the excess to go.

On other hand it also looks like you only have one solar inverter and the limit on that is around 7.8 kW (doing this from memory). So that could be the limiting factor. [edit: I just noticed that @SilverSp33d3r also noted that solar inverter limit]

 

[schan1w]

I'm curious about this also. I have the same design. How can 1 powerwall+ support a 12KW array? Someone correct me, but isn't the powerwall+ inverter only capable of converting 7.6KW fo AC power?

 

[Kilotango74]

So it is a 12.25 system with one powerwall and one powwervall+. No I do not have PTO, but am on self consumption only with the new powerwall+ setup. Once the battereis are full the solar production drops to only what the house requires. All that i understand. What i dont understand is why i only produce a max of 7.7 kwh. Like i said in my initial post i am not expecting 12.25, but for it to only go to exactly 7.7 everyday makes me think they are clipping max output as well.

 

[Kilotango74]

Wait……ok i think i understand. The max the batteries can take is around 7.7, and since i cant push to the grid it clips it at that point. That makes sense.

 

[slcasner]

Wait……ok i think i understand. The max the batteries can take is around 7.7, and since i cant push to the grid it clips it at that point. That makes sense.

No, 7.7 kW AC is the max that the inverter can output. So even after PTO you will have that same clipping. The 12.25 kW DC produced by the panels is more than the inverter can handle, so it cuts back on the input.

 

[arnolddeleon]

For those wondering about why the DC rating versus the AC rating sometimes is signally higher, the short answer is price/performance.

Yes, you lose some production when the inverter clips but in general you are better off spending the additional dollars towards more panels versus adding more inverter capacity. The panels will degrade over time, they will get dirty, etc. The efficiency curve of most inverters also offsets a little bit of the losses when it is clipping (by spending more time in the higher efficiency region).

 

[CrazyNavi]

Honestly seems like poor design by tesla, they should have installed 2x PW+, I would defiantly call and try to address that. You should be easily hitting over 7.7Kw production during the day, especially since you are in CA. Based on my math , you losing 4+ hrs a day at this time of the year, and in the summer months would be even more.

 

[SilverSp33d3r]

FWIW, I have a 12.24 kW system with two powerwall+. Split 18 panels each. My system has not ever produced more than 7.8 sustained peak in SoCal with zero shading.

Either Tesla’s software limits output or something ain’t right.

(Edit) yes I have PTO.

 

[CrazyNavi]

FWIW, I have a 12.24 kW system with two powerwall+. Split 18 panels each. My system has not ever produced more than 7.8 sustained peak in SoCal with zero shading.

Either Tesla’s software limits output or something ain’t right.

(Edit) yes I have PTO.

You might want to log in to the PWs during the day and see what you getting. I am Norcal with 8.16kW system, my peak last week was 6.1kW with single PW+ and 24panels. I would expect peak to be about ~75% of their panel capacity. I am sure someone else can share their numbers

 

[Kilotango74]

FWIW, I have a 12.24 kW system with two powerwall+. Split 18 panels each. My system has not ever produced more than 7.8 sustained peak in SoCal with zero shading.

Either Tesla’s software limits output or something ain’t right.

(Edit) yes I have PTO.

That is a great reference. Thanks. Makes me wonder why they sell larger systems if the max you can produce is 7.7.

 

[SilverSp33d3r]

You might want to log in to the PWs during the day and see what you getting. I am Norcal with 8.16kW system, my peak last week was 6.1kW with single PW+ and 24panels. I would expect peak to be about ~75% of their panel capacity. I am sure someone else can share their numbers

I have. Here’s the screenshot on a perfect clear day at solar noon.

 

[Kilotango74]

I have. Here’s the screenshot on a perfect clear day at solar noon.

Where do you log onto to see that info

 

[SilverSp33d3r]

Where do you log onto to see that info

Find the IP address on your network. Or connect to your TEG WiFi SSID

Connecting to Tesla Gateway and Powerwall+ | Tesla Support

If you lose internet or cellular connection, view instructions on how you can monitor your system’s power flow and charge level via web browser by connecting to your Gateway or Powerwall+.

www.tesla.com