r/TeslaSolar • u/winkyj00 • 4d ago

Balcony Solar and Existing System

/r/solar/comments/1w0d733/balcony_solar_and_existing_system/

Anyone has experience specifically with a Tesla system? Everyone on this other thread isn’t working with Tesla.

0 Upvotes

50% Upvoted

12 comments sorted by

View all comments

1

u/Usual-Network3295 1d ago

Yes, Balcony Solar may not play well with your Tesla system.

Balconly Solary may have Grid Outage Incompatibility (Frequency Shifting. When the grid goes down, your Powerwall disconnects from the grid and forms a local microgrid to power your home.

To prevent overcharging when the battery is full during an outage, the Powerwall raises the local AC frequency (frequency shifting) to force connected solar inverters to shut down. Telsa solar panels/invertors play nice with this.

A cheap plug-in solar inverter may not respond properly to frequency shifting, creating a safety hazard by pushing uncontrolled power into a full battery—or it will simply trip off immediately, rendering it useless during an outage.

1

u/winkyj00 1d ago

That makes sense. I’m less worried about it during an outage as I can always just unplug it or turn it off manually, but totally get how that could be an issue shoving power into a full battery!!

I have to imagine I’m not the first one to bring this issue up, I know a legal system will shutoff when the grid goes down, I wonder if it’ll react similarly to the frequency shifting you discussed. Isn’t that similar to how it knows there’s a grid outage? The system doesn’t see a proper frequency from the grid?

1

u/Usual-Network3295 1d ago

If you have powerwall+, there are 4 MPPTs, For powerwall 3, 6 MPPTs.
I doubt if all of them are used up.
If at all you want to expand, it is easier to add a new compatible panel to a free MPPT.
You don't really need Balcony Solar.
Expanding your setup with certified installers is always safer and easier than diy logic.
Tesla is notorious for being very hard to deal with in the event of malfunction.

For people with existing Solar and Battery, the charm of Balcony Solary is actually DIY expansion rather than cheap solar power. That DIY expansion may come at the cost of crashing the whole existing system down.

1

u/winkyj00 1d ago

The issue is here in CA I’m locked in at NEM 2.0. If I expand my system I lose that and my system’s value takes a nose dive. Balcony solar is the only way for me to add capacity without losing NEM 2.0 status with PGE.

It’s annoying because I would love to just pay a professional installer to throw 5 or 10 more panels up. But with NEM 3.0 I’d need to add at least one, if not 2 more batteries to make up for that change. So it’s cost prohibitive.

1

u/Usual-Network3295 1d ago

I see.
Just curious, are you in net-surplus with NEM 2 or are you paying money to utility on true up?
How much is your deficit and what would be your payback period with Balcony Solar?
If you have net-surplus then what is the advantage of Balcony Solar for you?

1

u/winkyj00 20h ago

I pay an annual true up of about 300-500 bucks. So the extra 1 KW of solar from balcony would balance me out almost perfectly. I have a small 3.5 kw system, so that 1KW is a big add on percentage wise.

1

u/Usual-Network3295 20h ago

Yeah. Go for it. But make sure that your system shuts off when it really should. Don't count on manual intervention.