on grid, but want off grid capability?

[nerdralph]

I just had another idea, is there just a way to trick my grid tie sunnyboy to not shut down due to grid being down? and then hook up UPS between whatever I want to run?

Yes. Switch the main breaker off to disconnect from the grid. Then connect your UPS (or genset) to the main panel.

[peakbagger]

No, No, No, you can not run a GT inverter on anything except the grid. The inverter not only needs an AC waveform to synchronize to - it also needs a close to infinite load to dump the solar power into. It will not run on a generator, it will not run on itself. However, SMA does make an "Island" inverter that is designed to create a little grid that the GT inverter can work off of, but it needs big batteries to absorb any or all of the power the GT inverter is producing.

I have a Sunny Island setup and three other grid tied arrays, when I switch to off grid operation, the other grid tied inverters, (two Fronius and 4 Enphase 215s) wait 5 minutes and start producing into the microgrid.. I had enough house loads running that I was not net surplus but with their frequency shifting approach I have no doubt the other inverters will shut down. There are two very large forklift batteries in the loop so no problem with absorbing excess power.

[PVAndy]

No, No, No, you can not run a GT inverter on anything except the grid. The inverter not only needs an AC waveform to synchronize to - it also needs a close to infinite load to dump the solar power into. It will not run on a generator, it will not run on itself. However, SMA does make an "Island" inverter that is designed to create a little grid that the GT inverter can work off of, but it needs big batteries to absorb any or all of the power the GT inverter is producing.

Are you saying that you can't use a Powerwall with a grid interactive SMA inverter/ That is not the case. When the Powerwall forms the microgrid and enables the SMA inverter, any solar power not used by the premise loads charges the battery. If the battery is fully charged the Powerwall changes the microgrid frequency and trips the inverter

Andy

[solarix]

No, No, No, you can not run a GT inverter on anything except the grid. The inverter not only needs an AC waveform to synchronize to - it also needs a close to infinite load to dump the solar power into. It will not run on a generator, it will not run on itself. However, SMA does make an "Island" inverter that is designed to create a little grid that the GT inverter can work off of, but it needs big batteries to absorb any or all of the power the GT inverter is producing.

[Ampster]

Tesla was supposed to come out with a off grid version but for whatever reason decided to not bring it out. The off grid version was supposed to have lower input voltage inherent to off grid systems. The version they currently market has a high DC input voltage more inline with Grid Tie systems.

I do not know what the internal DC voltage is because the battery and inverter are all in the same package. I would not be surprised if it was higher than 48 volts because they are used to dealing with higher voltage in the cars. The Gateway is separate and that is what manages the AC coupling. They do not have separate inputs for solar or generators so all they can do is AC couple, That does make them a useful addition to an modern GT system for someone who wants battery backup. A dealer I know in Southern California is no longer doing just solar installs. He has enough business backlog that he can pick only solar and Powerwalls. The same can be said for Tesla, they now only do solar with Powerwalls.

[littleharbor2]

Tesla was supposed to come out with a off grid version but for whatever reason decided to not bring it out. The off grid version was supposed to have lower input voltage inherent to off grid systems. The version they currently market has a high DC input voltage more inline with Grid Tie systems.

[Ampster]

One Tesla Powerwall would satisfy your needs It also requires a Tesla Gateway

Lots of users have installed Powerwalls to leverage their GT systems and provide backup. It uses the AC coupling to do that and the Tesla Gateway functions as an ATS but there is no provision for a generator. I had two Powerwalls on order but concluded I only needed the inverter capacity of one but wanted the battery capacity of three. I went with a hybrid and DIY battery pack. As far as I can tell I have the same functionality in my grid interactive mode. I am not sure how mudhole defines "off grid capability". Some Powerwall users have reported that since the Powerwall was designed to be grid interactive it does not function well as an off grid inverter, The lack of generator input is one of those functions that it does not have.

[PVAndy]

One Tesla Powerwall would satisfy your needs It also requires a Tesla Gateway

[mudhole]

Ya, I guess I wasnt thinking about the excess power created by the GT, it now makes perfect sense. I guess for my situation, the hybrid inverter would be the "best" way to go if I wanted that functionality.

[SunEagle]

so let me ask you this, if grid is out, i could in theory hook up a generator in place of the grid and the GT solar array would kick in?

Unfortunately a generator will not simulate the grid functions to allow your inverter to work.

[Ampster]

so let me ask you this, if grid is out, i could in theory hook up a generator in place of the grid and the GT solar array would kick in?

I doubt that a generator would pass the test for a grid that the GT inverter goes through. If it did the output of the GT inverter would overload the generstor.

[mudhole]

would be something if you could loop the GT inverter back to itself once the generator got it going, you would only need the generator to restart the loop.

[mudhole]

so let me ask you this, if grid is out, i could in theory hook up a generator in place of the grid and the GT solar array would kick in?

[Ampster]

ampster, can you elaborate on frequency?

When the grid goes down the hybrid grid forming inverter starts out at the nominal 60Hz. The GT grid dependant inverter does some tests and boots up. The hybrid measures the loads including battery charging and compares that to the output of the GT inverter. If the loads are greater, less Amps go to battery charging. if the loads are less the hybrid raises frequency to tell the GT inverter to ramp it's output down.
iF the GT inverter is older and can not modulate or ramp it shuts down. The cycle repeats. The UL 1741 standard determines how the GT inverter responds. If it is newer inverter built to UL2741SA spec it will modulate. If older UL1741 it will cycle on or off.

[mudhole]

ampster, can you elaborate on frequency?