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Contemplating solar -- roof, powerwall, and rate plan questions

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Hi all,

Never had solar before and due to a number of factors, considering installing it on the house this year. As background, I'm pretty much a newb when it comes to solar power and while I've tried to do some research, some of it seems to vary by locale or utility provider, so kid-glove, simple explanations will probably land best :)

Background on location and power use -- house is on the coast in the Bay Area -- so pretty mild most of the time (i.e. no AC) and I charge two electric cars at reduced rate overnight. Most appliances are still gas and bulk of our electricity consumption occurs overnight at off-peak rates.

First -- pretty sure our current roof is approaching the end of its useful life (or at least that's what we've been told -- it's 22 years old). Was planning on doing a roof replacement this year, and while I would love the solar shingle/roof product, I'm pretty sure the cost will exceed what I'm looking to spend (not even taking into account the availability). But as for the question on the roof topic:

Should I get the roof replaced independently before reaching out to Tesla (or other solar installers)? Or is there such a thing as Tesla or other installers doing an all-in-one service with roof replacement + solar installation?

Second -- very much interested in having Powerwalls installed at the same time. As I'm currently on a TOU plan with PG&E (EVA rate plan), can I set up it up so that (in the event that solar production doesn't meet electrical needs during the day) that most of my power is drawn from the Powerwall, ideally during peak periods? And, again, could the powerwall be set up to top up or charge overnight at low (off-peak) rates in the event that they don't get charged from the sun during the day?

Third -- as I mentioned, I'm currently on the EVA time of use plan with PG&E owing to the fact that I charge two cars overnight at reduced rate. Can I keep the EVA plan? How does that work with solar (billing, mostly what I'm wondering about)?

Thanks all!
 
@EV-by-the-Sea
First -- There are local roofers that do solar as well. Petersen Dean is one installer headquartered in Fremont. There is such a thing. Uncertain of the actual benefits of doing so. It might save you a day of home sitting, and a trip for the inspector.

Second -- Currently with the Tesla app, PW software 1.37.1 ... Advanced... Time based control... the peak period can be specified such that home runs off Powerwall and all solar is sent to grid for credits. Powerwalls in USA are not allowed to charge from the grid except during storm watch (a feature that based on some official warning of coming bad weather in anticipation high chance of power outage where allows Powerwall to fill up using grid power).

Third -- Today you can keep the EVA plan. With a Powerwall, you don't need a EV to qualify anymore. A new EVA rate plan is expected to be announced later this year. Prediction is it is well slanted against solar only customers. My analysis shows that with solar only, it doesn't matter what rate plan chosen. (i.e. don't factor rate arbitrage when solar sizing with an undersized system, go 110%.) I am grandfathered because my solar reached PTO prior to July 2019. My prediction is that there will be no more a EV rate plan. It will be called an ESS rate plan for storage customers only. The $1/gallon PG&E flyer was not included with my CARB rebate... I wonder why...
 
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The portion of the roof that is under the solar panels is considered to be a structural part of the system and is thus eligible for the federal tax credit. You should try to get both done at the same time if possible. If Tesla won't do it, look for other installers.

The Powerwall's time-based control (TBC) feature is set up to adjust the Powerwalls behavior according to the rate plan. Typically, it would be set to charge at a lower rate period and then discharge during the peak rate so all the solar generation during peak rate gets exported. You currently can not routinely charge from the grid in the US. Doing so would make the Powerwalls ineligible for the federal tax credit.

The way TOU plans work with solar billing is that your meter measures net flow from the grid to your house and charges you or gives you credit for the appropiate amount each day. These amounts are accumulated for a year and you pay the net amount at the end of the year. There is also a minimum charge of about $10 each month plus a 2-3 cent charge per kWh that you receive from the grid. You do not get the credit back at the end of the year. If you end up producing more (in kWh) than you consume, PG&E will pay you for that amount at a wholesale (read: minimal) rate.