Tesla says I have to purchase a second PW or they won't give me my referral Powerwall.

[jacobp]

Hello all. I was recently contacted by Tesla informing me that they are now ready to install my free referral Powerwall. I already have a 10.8 kw solar system that uses two 5kw SolarEdge inverters. After filling out the pre-nstallation survey, Tesla has told me that i MUST have two Powerwalls for my system. Here is the quote: "A single Powerwall is capable of taking in 5 kW of continuous energy and your solar system has 2 solar inverters that are rated at 5 kW each. This means that potentially your solar system at one time can produce double the kilowatts of what a single Powerwall system can handle and this would lead to malfunctions." If I refuse to purchase the second Powerwall (the first one, of course, is free), they will not install the free Powerwall. Instead they would give me a $5500 credit for future service, merchandise, or new car. Has anyone else run into this situation? Is there any suggestion I can make to Tesla that would allow them to install the free Powerwall?

 

[CA-Gbm84]

There are a couple of ways to look at it

• Will you be angry when your 10kW Solar system overloads the 5kW Powerwall and potentially causes damage?
• Is 1 broken free powerwall better than 2 working Powerwalls which you only paid for 1?

 

[jacobp]

There are a couple of ways to look at it

• Will you be angry when your 10kW Solar system overloads the 5kW Powerwall and potentially causes damage?
• Is 1 broken free powerwall better than 2 working Powerwalls which you only paid for 1?

I get what you are saying. My question is whether it is true that a single powerwall should not be installed in conjunction with a 10.8 kw solar system. If that is true, then my options are clear: buy the second powerwall or take the credit.

 

[power.saver]

Yes, that is true. You need 1 PW for each ~5kW of solar. So in your case, unless that 10.8kW solar is split across two inverters and you choose to only backup part of your solar, you need 2 PWs.

Do you have one or more than one inverter? What size are they?

For example, I have 11.5kW solar, on 3 inverters (5kW, 4kW, 2.5kW) and 2 PWs. The 2.5kW inverter is not on the PW backup circuit.

 

[Dan123]

It is possible to connect one inverter to the "inside" side of the PW Gateway, and connect the other to the "outside."

 

[Ampster]

Yes, that is the solution. Run the Powerwall off only one inverter. When the grid is down only one inverter will be functional. Otherwise both will work.

 

[gpez]

I have an alternative, no idea if Tesla would agree.

The Powerwall inverter is rated for 5kw continuous but 7kW peak for up to 10s "off grid" (source: https://www.tesla.com/sites/default.../Powerwall 2_AC_Datasheet_en_northamerica.pdf).

What does your 10.8kw rated system actually produce at max? My 8.6kw system is inverter clipped at 6.5kw, sounds like yours is 10.8kw but isn't clipped. I have 1 Powerwall which works fine because my actual max is less than the 1 Powerwall peak max.

Additionally you can configure your SolarEdge inverters to use "P(f) Power Frequency" which reduces the inverter's production during a grid outage based on the microgrid frequency the Powerwall sets. This can be used to ensure that the sustained output of your system is lower than the 1 Powerwall max during an outage. See page 6, https://www.solaredge.com/sites/default/files/application_note_power_control_configuration.pdf

 

[bkp_duke]

You have two inverters, simply solution is to just have the PW connected to one inverter. It requires converting the system into a "split system".

 

[jacobp]

Yes, that is true. You need 1 PW for each ~5kW of solar. So in your case, unless that 10.8kW solar is split across two inverters and you choose to only backup part of your solar, you need 2 PWs.

Do you have one or more than one inverter? What size are they?

For example, I have 11.5kW solar, on 3 inverters (5kW, 4kW, 2.5kW) and 2 PWs. The 2.5kW inverter is not on the PW backup circuit.

I have two 5kw inverters

 

[jacobp]

Thanks for all of the great advice. i really appreciate it.