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Does the solar contractor discuss that issue when selling solar or is it up to the homeowner?
The solar company I used (V3) partnered with a roofing company (Loveland Roofing). The roof is first checked by the roofing company. My written roof report basically said that I "need a new roof if solar is added or not". The roof on this house was as old as the house, built in 1997, so it was a 27-year-old roof. So no surprise there and now I have my new roof installed. The roof on this 1,920 SF house cost me 23.4K$, which wasn't too bad for CA.

While I soon will do the same with my Reno house, with a Tesla PowerWall, I probably do not need a new roof there, it still looks like new and is less than 15 years old. I have not yet looked into it and have not decided if I want to buy or rent solar for that house. I will wait until I get my first bills for this system and then figure out what to do there.

But I can tell you that I really like the way the Tesla Powerwall works, and that I will use in Reno too. I have full control over the system from anywhere I have a web connection. Things such as what percentage of battery I want to use at night, which can be handy. When I am not here, most of the energy gained will be sent back to PG & E.

-Don- Auburn, CA
 
Today, it's raining here in Auburn and kinda dark.

Right now, not even one watt out of my solar. But sometimes I am seeing as high as 100 watts today. And this is at 12 noon.

So how much it costs me or saves me off my PG& E bill really depends on the daytime weather and how long the days are. No doubt I lose big on days like today with my rented system.

But this is where being able to adjust the battery is handy. Last night, I made sure I mainly ran from the grid and kept the battery fully charged, so I would have a nearly fully charged battery in case I lose power today. Yesterday, I knew we would have a rather dark day today, so I adjust the battery so it would charge to full as I ran from the grid. Now the power can go out for the entire day, and I won't even notice unless I check my Tesla app.

Right now, by the time I completed this message, I am getting my 100 watts again from the solar, but this house is now drawing 500 watts. So at the cost of 400 watts.

I usually get around 4,000 watts from my solar at this time of day with most of that going back to the grid.

I have this computer and monitor on a UPS. I don't think I need this UPS much anymore. I am not sure if it will gain me time if the house battery went dead. It must draw some current, but it also has its own battery to extend the time. This UPS also runs my cable modem, router, security cameras, etc.

-Don- Auburn, CA
 
Today, it's raining here in Auburn and kinda dark.

Right now, not even one watt out of my solar. But sometimes I am seeing as high as 100 watts today. And this is at 12 noon.

So how much it costs me or saves me off my PG& E bill really depends on the daytime weather and how long the days are. No doubt I lose big on days like today with my rented system.

But this is where being able to adjust the battery is handy. Last night, I made sure I mainly ran from the grid and kept the battery fully charged, so I would have a nearly fully charged battery in case I lose power today. Yesterday, I knew we would have a rather dark day today, so I adjust the battery so it would charge to full as I ran from the grid. Now the power can go out for the entire day, and I won't even notice unless I check my Tesla app.

Right now, by the time I completed this message, I am getting my 100 watts again from the solar, but this house is now drawing 500 watts. So at the cost of 400 watts.

I usually get around 4,000 watts from my solar at this time of day with most of that going back to the grid.

I have this computer and monitor on a UPS. I don't think I need this UPS much anymore. I am not sure if it will gain me time if the house battery went dead. It must draw some current, but it also has its own battery to extend the time. This UPS also runs my cable modem, router, security cameras, etc.

-Don- Auburn, CA
The Tesla wall is just a larger version of your computer UPS.
 
I was just playing around with my system. Because of the lousy weather and possible outages today, I charged the battery to full from the grid. It charges up at around 2 KW from the grid, it's a 13.5 KWH battery (true useable KWH of the 14 KWH max battery). So from empty to a full charge will take around 6.5 hours or so.

At my current home draw rate (600 watts), a full charge will last me around 22.5 hours. Not bad at all.

I just deliberately turned off the grid from my Tesla app. Not even a slight flicker now that I am 100% running from the battery. The app shows when it switches the grid, only takes a few seconds.

I now just switched the grid back on, took a little longer, around 30 seconds. I guess to be sure it is in sync. The app says it can take up to five minutes to switch back on, but it took nothing near that much time.

Again, not even a flicker when the grid was turned back on.

I really like this Tesla Powerwall setup. I wouldn't want to change anything about the way it works. I can fully change the way it works at any time from any place from the Tesla app. Same app as my Tesla car, just on the next page.


-Don- Auburn, CA
 
The Tesla wall is just a larger version of your computer UPS.
Except my computer UPS doesn't sell electricity back to PG&E on nice sunny days (very unlike today!).

Today it was so dark in the middle of the day from the rain clouds that my solar only gave me about 1 KWH for the entire day.

Even the GPS in my Tesla couldn't always figure out my location because of the thick clouds. First time I have seen that happen since I purchased the car in year 2018.

-Don- Auburn, CA
 
UPS's draw negligible power unless charging after an outage. I wouldn't consider their "ungreen-ness" much in the grand scheme. Does the power wall supply the entire 200A or whatever service for the house or some subset of circuits?

Mark B.
Albuquerque, NM
 
Does the power wall supply the entire 200A or whatever service for the house or some subset of circuits?
No, if I am on battery power, the A/C will not work. AFAIK, everything else does.

IOW, they won't let me drain the battery down super-fast.

On 105°F. degree day, I am not so sure how well that will work out here if the power goes out.

Right now, I am drawing 600 watts in this house. My solar system is also putting out 600 watts right at 1010 hrs. The solar will soon be putting out a little more, but it is still very cloudy here. But not as bad as yesterday. So right now, the house is running on solar, but nothing is going back to the grid--yet.

-Don- Auburn, CA
 
It got sunny here quite quickly. Solar is now putting out 4.1 KW @1115 hrs. I am not sure why, but the house is now drawing 2.3 KW. Perhaps both refrigerator compressors just came on or something like that, not sure. But I am now feeding the grid with 1.8 KW, with the 2.3 KW going to this house.

Seems like a very big jump from the 600 watts this house was drawing a few hours ago.

The solar battery is not drawing anything, I have it set to charge to 71% SOC which it is already at and drawing no current.

It's beginning to look like the more solar output I get, the more the house load is, which doesn't make a lot of sense to me. But that is what I am now seeing as clouds go by past my solar panels.

-Don- Auburn, CA
 
Maybe there's some form of load shedding happening? That's why I asked what the battery was powering, and it would make sense that based on your setpoints the "smarts" would steer energy towards the desired loads. Now, how that effectively happens would be the question. Without doing some major surgery to your load center (breaker box) gotta wonder how that's happening. It would stand to reason maybe one phase is being supplied from the inverter, having a split phase supply would be trickier and still isolate 240V loads (A/C, and others). Seems knowing how the power wall and solar inverter is supplying energy to what, under what conditions would be a useful data point so you can intelligently manage your power even better.

Mark B.
Albuquerque, NM
 
Maybe there's some form of load shedding happening? That's why I asked what the battery was powering, and it would make sense that based on your setpoints the "smarts" would steer energy towards the desired loads. Now, how that effectively happens would be the question. Without doing some major surgery to your load center (breaker box) gotta wonder how that's happening. It would stand to reason maybe one phase is being supplied from the inverter, having a split phase supply would be trickier and still isolate 240V loads (A/C, and others). Seems knowing how the power wall and solar inverter is supplying energy to what, under what conditions would be a useful data point so you can intelligently manage your power even better.

Mark B.
Albuquerque, NM
Yeah, I do not really know how the thing works. Right now, I am getting 4.1 KW from my solar, 2.4 KWH going to the house and 1.7 KW going back the grid.

For sure what I am seeing on my app shows the more power supplied from the solar, the more power the house draws.

I have no idea why it shows such, but I too am fairly sure I am not seeing everything possible on my Tesla App.

-Don- Auburn, CA
 
Since my solar system went in on 4/17 at the end of the day, I gained 354 KWH. That will be the same as charging my Tesla LR 80KWH battery from totally empty (less than 0% SOC) to 100.0% SOC 4.425 times.

The first day and on 4, May 2024 (the very dark day here) I gained almost nothing, but about 22.5 KWH gained per day average on the rest of the days which have been mostly sunny.

So at least I now know my EVs are not putting any stain on the grid, in fact, I am doing much the opposite. I don't charge anything near that total of 354 KWH in such a short amount of time.

-Don- Auburn, CA
 
I just checked on the web to see what a solar system like the one I have at my Auburn house will cost (Tesla Powerwall, 4.5 KW solar, etc) all installed. $23,500.00. And rebates can reduce to cost to around $16,500.00 but that varies by area.

I am considering buying the entire system for this house and continue to rent the one for my Auburn house. Not sure how it will all compare when a KWH in Auburn costs almost three times the price of a Reno KWH.

I spent more than that on my last couple of motorcycles. Not really out to save money on the deal, I mainly just like the idea.

I already made an appointment for tomorrow here to talk about the details. I already know what I want ,at least. A system exacly like the one I have in Auburn. I would probably want twice the solar if I stayed at one house, but 4KW is more than enough only being at each house around half the time. A lot more sun here in Reno, and no large trees when the sun goes down. I am on the very top of the sunny hill here.

But I don't expect to get much from this system in the winter when the solar is going to be just a snow holder.

-Don- Reno, NV
 
Maybe there's some form of load shedding happening?
I asked in the Tesla forum.

It is usually caused by misconfigured CTs (Current Transformers) which is VERY common with new home solar installations.

I will find out more later and see if I can have it fixed. I assume it only affects my app and what I am seeing on it isn't exactly for real.

-Don- Reno, NV
 
Current transformer is a term I associate with current monitoring, like a hall sensor. Back in the day it was a donut you'd pass your wire through and it had an output at some proportion to current through the wire. Interesting the response would be dynamic, you'd think once set up it would be consistent. Whatever, all part of the learning curve and you'll probably find out more about this system than you ever thought you needed to know.

Mark B.
Albuquerque, NM
 

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