Expected Behavior During Grid Outage

[skepticcyclist]

@BGbreeder Sorry, I meant why can't we have smart transfer switches (like in the Gateway) that allow solar production to continue when the grid is down. Thought that's what we were talking about. I'm well aware of the safety issues and protecting line workers.

Off grid systems throttle solar output to match usage, I never understood why they wouldn't make grid tied systems do the same during an outage

 

[BGbreeder]

Off grid systems throttle solar output to match usage, I never understood why they wouldn't make grid tied systems do the same during an outage

Well, Enphase's IQ8 can and does, but adding in the extra grid forming circuitry to do that is a non-zero cost. To your question of why inverter manufacturers generally don't add in the grid forming circuitry, I think a primary issue is cost, but complexity is certainly another. Many solar customers are cost sensitive and might be (are?) put off by systems that cost more.

There is still the general issue of matching load to PV output; powering lots of little devices like phone chargers and laptops is one thing, but running microwaves or starting ACs are another, and it gets into a complex area of how much voltage undershoot ("brown out"), and overshoot is acceptable for how long.

I have operated a number of off grid systems over the years, and I would say that in my experience mechanical generators have some advantages of stored energy in the rotational inertia of the engine and armature (rotor) that help with instantaneous load changes that solar inverters have to manage by circuitry with relatively little energy storage. Hence my prior comment about solar plus storage being much easier to operate than just pure solar. Can it be done without storage? Sure, but it is neither simple, nor easy, nor inexpensive.

All the best,

BG

 

[Matt-FL]

Wow, that was easy. Spun up an online chat with Tesla support and they sent it off to the group to make the change. Said it should be complete in 10 days or less.

Thanks for the tip!

Just following up on this, Tesla contact me 6/21 to let me know they had completed my ticket to adjust hz frequency during an outage/batteries full. For now, I'll just take their word for it, until we have another outage/stars align/batteries full.

Not bad, 9 days from ticket open to ticket complete.

 

[jjrandorin]

Just following up on this, Tesla contact me 6/21 to let me know they had completed my ticket to adjust hz frequency during an outage/batteries full. For now, I'll just take their word for it, until we have another outage/stars align/batteries full.

Not bad, 9 days from ticket open to ticket complete.

If you have a kill a watt type device you can test it yourself, by going off grid (not the app, actually throwing your main breaker and going off grid) and seeing what frequency the power is.

When I got mine changed, I specifically bought a device to test it so that I knew it would work when I needed it. The time to ping tesla if its not working is right now (right after they closed your ticket saying "its done"), so its a good idea to take a look at it imo.

You just need to get something that can show power frequency. I would link the one I bought but it has doubled in price since I bought it (current price seems to be in the $30 ish dollar range vs $15 ish when I bought it, for pricing references).

 

[Matt-FL]

I can see the frequency via Powerwall Power Flow app. In order to see this in action though, I'd need to wait until my powerwalls are 100% charged, then push the system into 'off grid' mode. Easy enough, but figure I'll be able to track without forcing a reboot of my inverters (which would happen in the situation above), I'll just wait until the next grid outage, then I can check the charts and the audible test (are my UPS's beeping?)