System expansion after the fact

[craigcabrey]

Curious if anyone has tried this before. I have an 8.5 kW system on order (currently 340W panels, they are redesigning to use their 425W panels), presumably with a 7.6 kW inverter.

The 7.6 kW variant has 4 MPPTs. With my design, I'm assuming Tesla will be using 2 of them (one 3.4 kW East facing array, one 5.1 kW West facing array). This leaves two MPPT free.

I have a perfectly good front porch that Tesla refuses to put panels on. I'm wondering if I might be able to DIY adding panels to the system by adding a third string. Minimum voltage is 60V per string, so three 340W Q-cell G6+ panels can make a string (they are rated at minimum ~32V). I can source these panels myself and install myself.

Adding a string should just be plug and play, right?

 

[jjrandorin]

Do you also plan on pulling permits etc for that additional DIY work? I dont know enough to speak to the technical question, but I think one big problem would be, if you ever had any issue with your system, tesla wouldnt want to fix anything because "someone else" did something.

This is one reason why you will find that almost no one will touch another solar companies work. They will all add a NEW system to your home, but no one will touch an existing one, They dont want liability for the work they didnt install, and if they add to an existing system, the company that did the first install is now off the hook because "someone else, touched something else".

Given you expect to have a warranty of 10-20 years, and are not DIY ing the entire thing yourself, that likely should be a big consideration.

 

[nwdiver]

Adding a string should just be plug and play, right?

As long as Tesla inverters are like other inverters on the market, yes. But I wouldn't be too surprised if Tesla does something 'crazy' like disabling unused MPPT channels or something and who knows how the warranty would be addressed....

 

[Vines]

Curious if anyone has tried this before. I have an 8.5 kW system on order (currently 340W panels, they are redesigning to use their 425W panels), presumably with a 7.6 kW inverter.

The 7.6 kW variant has 4 MPPTs. With my design, I'm assuming Tesla will be using 2 of them (one 3.4 kW East facing array, one 5.1 kW West facing array). This leaves two MPPT free.

I have a perfectly good front porch that Tesla refuses to put panels on. I'm wondering if I might be able to DIY adding panels to the system by adding a third string. Minimum voltage is 60V per string, so three 340W Q-cell G6+ panels can make a string (they are rated at minimum ~32V). I can source these panels myself and install myself.

Adding a string should just be plug and play, right?

Assuming you have the MCI as well, you could self install this. However, the concerns above do apply, and perhaps others. Also, 90V string is pretty low. I know the inverter will generate something but not sure what fraction of the output from 3 modules you will get.

Porches are often not the most structural elements, so I can see why they may hesitate.

Why not just use a small microinverter setup for the last 3 panels and self-install that? AC is much more forgiving than DC.

 

[yblaser]

Porches are often not the most structural elements, so I can see why they may hesitate.

I get why Tesla wouldn't want to install on a Porsche especially a Taycan.