# of Powerwall 2's

[Theedge555]

Hi - First time poster, short time reader/viewer of TMC

Recently had Tesla Solar Panels installed on the house here in New Jersey. We started the process back in mid February, panels were installed in early June, now waiting for the power company to install their new meter. Overall we've been impressed with the Tesla communication/installers/follow-up. Once I turn on the system, I'm sure we'll be more excited.

5.185kw with 17 panels

We're also on the list for the Powerwall 2, in late 2018 or early 2019. 1 PW I'm quoted 9.5k installed (before tax credit), 2 PW's for 14.5k (again before tax credit).. The question to the group, do I go with 1 or 2 PW's? We've been in our home for nearly 3 years and no major disruptions in terms of electricity. Is 2 PW's truly needed? I'll also mention that that we're expecting a Model X delivery in early September 2018 so I'm thinking of going with 2 PW's. Thoughts? We can charge the X during the overnight, using the PW stored energy through our own energy, releasing it's stored power, no? Also, what's the life expectancy of the PW is 10+ years?

Any help/recommendations is much appreciated! Thanks.

 

[AndreSF]

I have a similarly sized PV system (5.85kw), 1 PW, Model S. One PW is sufficient (as a backup system) for our needs based on the number of circuits being backed up by PW. I would go with one PW, but it depends on your home needs and how much you want to be in the "self-powered" mode. I don't mind drawing from the utility when charging the car at night, as they owe me a considerable amount of kwh generated by PV system anyway.

 

[reddy]

Good luck on getting any actual Powerwalls. I have been waiting since September 2017, with no delivery in sight.

Calling Tesla is useless. I keep getting excuses. This month the excuse is that all batteries are diverted to Model 3 production.

Apparently they pulled the sales people out of the hundreds of Home Depot’s they were staffing to sell Powerwalls. Powerwalls that aren’t really available.

 

[cwied]

I went with two Powerwalls because I want whole-house backup. The system will only back up loads on breakers sized up to 30 amps per powerwall. To back up a load on a 60 amp breaker, you need two Powerwalls. Also, each Powerwall will only delivery a maximum of 5 kW continuous.

Do you have Net Energy Metering? Because of the round-trip loss of storing energy in the batteries and then discharging it back to charge your car, it's better if you can have a more direct way to charge the car. Also remember that each powerwall only holds 13.5 kWh of energy, so if you drive a significant amount it's not hard to completely drain your Powerwalls when charging a car. Net Energy Metering is a more efficient way of charging the car if your utility offers it.

 

[RFernatt]

Good luck on getting any actual Powerwalls. I have been waiting since September 2017, with no delivery in sight.

Calling Tesla is useless. I keep getting excuses. This month the excuse is that all batteries are diverted to Model 3 production.

Apparently they pulled the sales people out of the hundreds of Home Depot’s they were staffing to sell Powerwalls. Powerwalls that aren’t really available.

Same here. Waiting since May 2017. The PW2s and/or batteries are going to Australia, Puerto Rico, Model 3s, or pick some other destination of the month. It would be better to just say we're constrained on battery production and we have no idea when you will get your unit.

I have an 11.3 kW PV system that needs a battery to operate when the grid is down and it needs to arrive before the tax credit ends. I'll have to find another option at some point.

 

[arnolddeleon]

Make sure you are clear on your reasons and goals. Is it backup only? Do you just want the satisfaction of consuming power your systems produced? Do you want to shift loads (do you have time of use metering?) Are you trying to save money? @cwied already raised the key points and question. A charging car will empty your batteries pretty quickly. I don't think I've heard of anyone complaining about having too much battery. In my case because of TOU I expect the system will pay for itself over the warranty period and so I get backup for free. I need to add controls so my cars will stop charging if the grid goes down at night.

 

[Theedge555]

Thanks all for your responses - Yes, to Net Energy Metering - Here in NJ SREC's are on the high side - Nearly $210 per credit - According to my system, we'll be able to generate 6-7 credits a year.. Home has Central Air so to have that hooked in to the PW, I'll need two...

My current commute is 30 miles round trip, so plugging in to PW at night shouldn't drain completely. Could I drain the battery if I wanted back to the grid and refill during next day (from solar panels)?

According to my conversations with Tesla Energy Advisor, if order is placed, we'll get the 30% tax credit regardless if delivered in 2019...

Thanks again...

 

[cwied]

You cannot discharge to the grid. You can only discharge to offset your house load. The main point on the EV charging is that you'd be better off charging from the grid overnight and using the powerwall to export more solar during the day if you have NEM. I don't think SRECs work like NEM, though, since you get those credits even if you use the electricity that they represent, right? Do you get any credit for electricity you feed back into the grid, or are the SRECs the only credit you get?

 

[reddy]

According to my conversations with Tesla Energy Advisor, if order is placed, we'll get the 30% tax credit regardless if delivered in 2019...

I would like more information on how this works.

The IRS says : "For purposes of both credits, costs are treated as being paid when the original installation of the item is completed".

So Tesla tells you to take the credit, even when NOT completed? I think my accountant would have serious chest pain with that advice.

https://www.irs.gov/pub/irs-pdf/i5695.pdf

 

[Theedge555]

I'll follow back-up with the Energy Advisor - But if installed in 2019, still eligible for the tax credit - 2020 looks to be a decrease to 26%