Do I need a UPS

[bob_p]

After getting the PowerWalls/solar panels installed, you should run an "off-grid" test, simulating loss of grid power and verifying the new system properly transitions to off-grid mode, and turns off/on the solar panels (based on PowerWall charge level) and then returns to grid mode.

During this test, it's easy to find out which devices inside the house are impacted by the switch from grid to local power - and then add UPS for those devices, if you don't want them to reboot when grid power is lost.

These UPS boxes should only be needed to provide power for a few seconds while the TEG takes control, sets the powerline frequency and uses power from the PowerWalls and solar panels for house power.

This means you may not need to invest large UPS boxes - since they will only be needed for a few seconds...

Note that some UPS boxes may not work correctly if the power isn't at 60Hz - we have one of our UPS boxes that we pulled from use because it refused to work when the TEG set the frequency above 60Hz.

 

[zƬesla]

New After getting the PowerWalls/solar panels installed, you should run an "off-grid" test, simulating loss of grid power and verifying the new system properly transitions to off-grid mode, and turns off/on the solar panels (based on PowerWall charge level) and then returns to grid mode.

Make sure this test also takes into account when you're at near full PV. We've been having various issues with a new install when nearing peak PV production including inverter shutdown, UPS triggering, clocks resetting, and lights flickering. This is still being troubleshooted; just glad it was discovered right away by us conducting an off-grid test and not in a real outage situation (for which we purchased the system).

 

[jrweiss98020]

I ran a 2-day off-grid test last Aug while awaiting the utility's final inspection. I didn't even notice any switchovers from PV to PW or back.

Subsequently, I have noticed a couple UPSes trip when the grid goes down, because they're faster to react than the PWs. Generally they switch back off within a second or 2.

 

[bob_p]

The off-grid test should be done twice:

• When PowerWalls are below 95% charge. The TEG should switch over to using power from the PowerWalls and solar panels, setting the powerline frequency at 60 Hz. There may be up to a several second delay before power is restored while the TEG gets configured for off-grid operation.
• When PowerWalls are at 99-100% charge. The TEG should switch over to using power only from the PowerWalls and turn off the solar panels by setting the powerline frequency higher than 60 Hz (default has been 63 Hz; Tesla can manually adjust this downward upon customer request). Some devices may have difficulty running at 63 Hz; and if this happens, request Tesla to lower the solar cutoff frequency.

These tests really should be part of the normal testing performed by the installer, before they turn over the system to the customer, otherwise how can they be confident the system is actually working correctly?

 

[jboy210]

I ran a 2-day off-grid test last Aug while awaiting the utility's final inspection. I didn't even notice any switchovers from PV to PW or back.

Subsequently, I have noticed a couple UPSes trip when the grid goes down, because they're faster to react than the PWs. Generally they switch back off within a second or 2.

Same here.

When were doing a test with the PWs they cut the power. The Gateway cutover was so quick the lights did not flicker, TV did not lose picture, etc. But I heard a click from the UPS. And when I walk over its display said it was providing power. After a minute the UPS quit providing power and started recharging its battery.