Solar + Powerwall: Flickery lights

Solar + Powerwall: Flickery lights

We've just wrapped up a new install of a 7kW system with 2x powerwalls, and shortly after the install we were finding weird behavior like lights randomly dimming (it looked like what you would imagine an unstable power supply might yield). I contacted Tesla and a couple of (awesome) technicians came out. After spending quite a long time they discovered that the main power input wasn't secured correctly (literally, the big fat cables coming from the main power grid weren't screwed in securely.. eek) and their theory was it was shorting.

After they left things seemed fine, but we intermittently still have flickering lights, though not as bad as previously. We had also recently replaced most incandescent bulbs with (dimmable) LEDs, but that was prior to the solar install and we didn't have any issues before the solar install.

What's the view here? Is there something "wrong", or is this just a side effect of having solar+powerwalls+grid and software switching between them or mediating power flow? Anyone else seen this?

I'm worried that tracking down the issue might be so difficult as to be nearly impossible.

bp | February 19, 2020

If you replaced incandescent bulbs with dimmable LEDs, did you also replaced the light switches?

Older dimmer switches may not be compatible with dimmable LEDs.

Is this happening while the system is operating with grid power connected? If so, then unless you have a wiring issue, it's unlikely the solar panels, (micro)inverters, PowerWalls or Tesla Gateway would have any impact with the house power.

If this is happening when operating off-grid and the PowerWalls are close to full charge, the Tesla Gateway will change the powerline frequency to 65Hz (by default), which should turn off the solar panel (micro)inverters so that the solar power isn't being fed into the house with nowhere to go. Some devices (UPS, air conditioners, pool pumps, refrigerators, ...) don't like running at 65Hz - and that might also impact your lighting.

If this is what you are seeing, contact Tesla Energy support and request they lower the solar power shutoff frequency (61-62 Hz should be enough to shut off the solar power while not impacting devices).

We have dimmable LEDs in multiple locations throughout our house, and we haven't seen any problems when operating only on solar/PowerWall power or when we are operating off grid. We had a few full sun days and ran completely off-grid, solely on solar/PW power for 3 days - and didn't experience any problems with our LED lights or any other devices.

gregbrew | February 19, 2020

Earlier this year, my lights pulsed on and off at about a one hertz rate when the grid went down and the PWs took over. I called Tesla, and the first-level tech (female!) was able to poll the PWs to find that they were reporting close to 100A surge current when they were trying to come up. (Two PWs can only provide 10A). They gave up, and dropped out, only to try and come up again, with the 100A load. Lather, rinse, repeat, and you get pulsing.

She asked if we had large devices that could look like such a huge load at start-up.

Just three refrigerator/freezer compressors and *two EVSEs* that happened to be plugged in at the time. The two EVSEs alone were way more than 10A, and the compressor surge on the fridges probably accounted for the rest. Without the EVSEs, the PWs came up fine, as they likely have a surge-current capability specifically for refrigeration inductive motor loads.

Oops! The PWs were doing just as they were designed to do...

BTW, Tesla adjusted the default PW frequency output during grid failure and full batteries (on non-microinverter installations) to be much tighter than the 65Hz you described. *Many* people were complaining that UPSs wouldn't go back to line power on PWs because the frequency was too far out of spec, and the UPS depleted their internal batteries when PW-provided line power was actually OK for connected equipment. This happened to mine. Since they tightened it up (in 1.43, IIRC) my UPS has worked fine during a grid failure.

gregbrew | February 19, 2020

Sorry, the previous post should say that the "two PWs can only provide 10kW" (not 10A), and the EVSEs took more than 10kW (not 10A).

Haven't had my coffee yet...

Passion2Fly | February 20, 2020

If lights are flickering with the grid up, it’s a wiring issue. Unless you have LEDs on old dimmers. If the lights are flickering with the grid down, it’s most likely a PW overload... I once turned on the electric cloths dryer after the power went out and it did just that until I turned the dryer off...

aid000 | February 26, 2020

I had Solar + PW installed recently and I am also observing light flickering throughout the house after installation.
This impacts mostly LED lights - as I do not have many incandescent light (I think I replaced all of them by now). I observe this issue at night and in the mornings when the house is powered by Powerwalls .. with typical total load less than 0.5 kW and Powerwall capacity between 50% and 80%.
Did anyone got similar issue addressed?

rmasters | March 24, 2020

Is this happening when the lights are already partly dimmed? I've noticed that since our PW was installed, a couple of bulbs will occasionally flicker when dimmed to about 20%. As soon as I adjust the light level, the flickering stops. They are dim-able LED's and the switches are designed to handle LEDs.