I would say that hydro is renewable because it operates on the rain and snow that falls in the mountains and then runs downhill. A drought in a hydro project is analogous to nighttime on a solar panel, or a calm day on wind. Hydro may not be reliable during a drought, but it is renewable. Until it stops raining entirely.
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Switched on my system today!
- Thread starter daniel
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I would say that hydro is renewable because it operates on the rain and snow that falls in the mountains and then runs downhill. A drought in a hydro project is analogous to nighttime on a solar panel, or a calm day on wind. Hydro may not be reliable during a drought, but it is renewable. Until it stops raining entirely.
Time shifting loads is beneficial, but adding loads just to max out production is not. A truely oversized array is a problem from the extra inital cost standpoint only.
Your powerwalls would be better off if you charged the car when there was solar overproduction instead of cycling them. (Assuming you are home then).
One option I've seen is using an AC unit to freeze water at night and then use that to cool in the day. With your setup, you could potentially run AC 100% when the Powerwalls are full so that the cooling load is less later when the solar production drops.
Congratulations!
Your Tesla app should definitely be showing you what’s happening with your PowerWalls if you have a Tesla Gateway as part of red System—which you should.
We’rd Just a few miles from you upcountry, and we’re currently rly showing (under the upcountry cloud cover 5-8kwh being generated (as clouds thin and thicken) , 1kw going to house draw (pool pump), 4-6 going to PowerWalks. Model 3 set to begin charging at 2:30/-my best guess on a partly cloudy day fir PowerWalls to be fully charged and power to get sent to grid (where we grab ifor car first.)
Check your installer as to why PowerWalls not showing up in Powerflow portion of your Tesla app.
My problem (a temporary one) is that without a 240-v. outlet in the garage, the car takes forever to charge. I agree that it's better to use the power directly when the sun is shining than to cycle the Powerwalls. But I'm still learning how much power I get and what I can do with it. Right now it is 2:15 p.m., I'm getting 8.1 kW; 1.5 of that is going to the car, because that's all it will take on 120 v., the A/C uses 4.5 kW of it when it's on, which is maybe (?) half the time; and the rest is going to the Powerwalls.
You misunderstand me. On the app I can see everything. But Tesla does not have (as far as I know) any way to monitor the system from my desktop computer. I'd like to just have a window open on the desktop computer, where I could see it all the time, rather than having to use the tablet or phone. The My Tesla page on the web site shows my car, but to see the solar installation I have to use the mobile app.
You mean like this?
Snaggy - easy screenshots
That requires a LibreNMS server though which may be overkill for what you're after.
I don't see how a screenshot-sharing application would give me the ability to monitor my Tesla energy system on my desktop computer.
I'm kind of getting the hang of things. Charge the car when there's excess power. Plan washing in the early afternoon when production is high. Stuff like that. My main power use is for A/C and that has to run when needed, but is mostly needed when there's a lot of sunlight. It draws down the batteries in the late afternoon when the sun is weak but it's still hot out. And the big west-facing windows let a lot of heat into the house when the sun is too low in the sky to make much power. But the Powerwalls handle that easily.
Now the big thing I'm wondering about is an apparent discrepancy between power produced and power consumed. According to the Tesla app, over the past three days, my house has consumed far more power than my solar panels have produced, yet there's been almost no draw from the grid. Over the past three days, the house has used 86.5 kWh, the panels have produced 64.4 kWh, for a shortfall of 22,1 kWh, but the house has only drawn 0.5 kWh from the grid.
The cottage has a different use pattern. My own electric use is almost all daytime, and I can turn off the A/C when I go to bed. My renter is away at work all day, her Powerwall is full by noon, and she comes home around sundown so almost all her electric use is after sundown and must come from the Powerwall. So the cottage has consumed 44.2 kWh over the last three days, the panels for the cottage have produced 33.3 kWh, for a shortfall of 10.9 kWh, but has only drawn 10.9 kWh from the grid. This may be skewed, though, because the cottage drew 5.9 kWh from the grid that first day, and only 0.9 kWh the past two days.
I'll report if this discrepancy rectifies itself, but I'd be interested if anybody has any thoughts: Is there something I'm not taking into account? Is the Tesla app just really inaccurate? I assume that "House" is supposed to be all the power consumed by the house, whether from the panels, the batteries, or the grid; that "Solar" is supposed to be all the power produced by the panels whether it's consumed directly by the house or sent to the batteries (I don't send power to the grid); and "Grid" is supposed to be all the power drawn from the grid, which should only be going to the House. The power to and from the Powerwalls should not make a big difference other than efficiency losses, because the Powerwalls for the house are always up around 60% or 65% when I go to bed and always round 30% when I get up, and the Powerwall for the Cottage is always a bit higher than that when I go to bed and always near empty when I get up.
woferry
Member
The link title in post #25 is misleading, the point wasn't the sharing site, but the image he shared on it (when you click the lik), which shows how his setup displays the solar data.
Sounds like some of your CTs (current transducers) may not be installed/set-up properly. There might be other options, but in my install there's a pair of CTs measuring power going to/from the grid, a pair of CTs measuring power from the solar, both of which are monitored by the Neurio inside the Gateway, and the Powerwall(s) inform the Gateway of their input/output. So the Gateway gets direct measurements for 3 of the 4 'paths' shown in the Tesla app, and the fourth (Home) is derived from the other 3 readings. My system is a bit more complicated because there are two solar inverters and my service panel had no easy way to get a true grid reading, so the solar CTs each have two wires passing through, and the grid CTs also have 2 wires (the one solar inverter that is on the grid-side of the Gateway, and the circuit that goes to the Gateway, I have no non-backed-up loads, those are the only two circuits in my original service panel). After the install Tesla had gotten both of these wrong for me, and one of the two wires in every CT needed to be turned around to get the proper readings. But while things were wrong I definitely got funky readings. I did my own troubleshooting and corrected the bad wire directions in my setup, but I was comfortable/familiar with my house wiring and the work that Tesla did. Assuming your two setups are separate with their own Gateways it doesn't seem like your wiring should be as complicated as mine, but if they had trouble getting the grid CTs in the right spot you might get a funky reading from them I suspect.
Sorry, I didn't dig through the thread to verify, do you still have loads that are not backed-up? Also, do your inverters have displays on them, where you could double-check what they say they produced near the end of the day vs. what the app is reporting? Or any other monitoring for the solar independent of the Gateway? If your meter is digital you can also compare its reading to the app's Grid value in real-time to see if they agree (bit harder to do with an old wheel meter, not sure if anybody with solar still has one of those).
But when set up properly the Tesla app should be quite accurate, at least it is for my setup, the only issue I have is that the solar side reports ~20W produced even when the inverters are off, which amounts to ~0.2kWh or so excess solar production per-day (will get a bit worse as the days get shorter).
Sounds like some of your CTs (current transducers) may not be installed/set-up properly. There might be other options, but in my install there's a pair of CTs measuring power going to/from the grid, a pair of CTs measuring power from the solar, both of which are monitored by the Neurio inside the Gateway, and the Powerwall(s) inform the Gateway of their input/output. So the Gateway gets direct measurements for 3 of the 4 'paths' shown in the Tesla app, and the fourth (Home) is derived from the other 3 readings. My system is a bit more complicated because there are two solar inverters and my service panel had no easy way to get a true grid reading, so the solar CTs each have two wires passing through, and the grid CTs also have 2 wires (the one solar inverter that is on the grid-side of the Gateway, and the circuit that goes to the Gateway, I have no non-backed-up loads, those are the only two circuits in my original service panel). After the install Tesla had gotten both of these wrong for me, and one of the two wires in every CT needed to be turned around to get the proper readings. But while things were wrong I definitely got funky readings. I did my own troubleshooting and corrected the bad wire directions in my setup, but I was comfortable/familiar with my house wiring and the work that Tesla did. Assuming your two setups are separate with their own Gateways it doesn't seem like your wiring should be as complicated as mine, but if they had trouble getting the grid CTs in the right spot you might get a funky reading from them I suspect.
Sorry, I didn't dig through the thread to verify, do you still have loads that are not backed-up? Also, do your inverters have displays on them, where you could double-check what they say they produced near the end of the day vs. what the app is reporting? Or any other monitoring for the solar independent of the Gateway? If your meter is digital you can also compare its reading to the app's Grid value in real-time to see if they agree (bit harder to do with an old wheel meter, not sure if anybody with solar still has one of those).
But when set up properly the Tesla app should be quite accurate, at least it is for my setup, the only issue I have is that the solar side reports ~20W produced even when the inverters are off, which amounts to ~0.2kWh or so excess solar production per-day (will get a bit worse as the days get shorter).
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You can use your desktop browser and just put in the IP address of your gateway to see a screen very similar to the Power Flow screen in the Tesla app. When I WFH, I have that tab open and toggle back and forth to see it throughout the day.
AFAIK, there's no way to view historical data via the gateway yet but Tesla will be adding an supported option to export our data soon.
@woferry:
I am going to expose my ignorance here, but when you ask "do you still have loads that are not backed-up?" I don't know what that means. I presume that a "load" means anything that draws power. But I don't know what it means for a load to be "backed up." For the house I have the solar panels (of course) and two Powerwalls. I'm connected to the grid so the system can draw grid power when it needs to, either because I don't have enough capacity at the moment, or for compensating for fast changes in production or demand. But the utility won't buy my excess or even take it for free. Occasionally I am feeding a little back to the grid, but it's very small amounts and only lasts for a second or so.
The cottage is on its own completely separate system, separate gateway, separate inverter, separate electric meter, but is otherwise the same arrangement, other than having half as many solar panels and just one Powerwall.
If I continue to see the discrepancy for the next couple of days, I will talk to my contractor, and mention what you said in your post. He seemed to know what he was doing however.
FWIW, the numbers reported on the Power Flow screen always add up correctly. Only the totals on the Yesterday screen don't balance. (I've never paid attention to the Today screen.)
@MorrisonHiker:
Thanks for that information. I will ask my contractor for the IP addresses of the gateways.
I am going to expose my ignorance here, but when you ask "do you still have loads that are not backed-up?" I don't know what that means. I presume that a "load" means anything that draws power. But I don't know what it means for a load to be "backed up." For the house I have the solar panels (of course) and two Powerwalls. I'm connected to the grid so the system can draw grid power when it needs to, either because I don't have enough capacity at the moment, or for compensating for fast changes in production or demand. But the utility won't buy my excess or even take it for free. Occasionally I am feeding a little back to the grid, but it's very small amounts and only lasts for a second or so.
The cottage is on its own completely separate system, separate gateway, separate inverter, separate electric meter, but is otherwise the same arrangement, other than having half as many solar panels and just one Powerwall.
If I continue to see the discrepancy for the next couple of days, I will talk to my contractor, and mention what you said in your post. He seemed to know what he was doing however.
FWIW, the numbers reported on the Power Flow screen always add up correctly. Only the totals on the Yesterday screen don't balance. (I've never paid attention to the Today screen.)
@MorrisonHiker:
Thanks for that information. I will ask my contractor for the IP addresses of the gateways.
You should be able to log into your router and see a list of connected devices (including your gateway) and their IP addresses.
Once you have your IP address, just enter it in your web browser and you'll see something like this:
You may notice that the numbers don't always add up. That's because the gateway never/rarely shows the flow between the grid and the Powerwalls.
dandrewk
Active Member
When designing the system, you have the option of which power circuits (loads) you wish to have backed up. Most will choose "whole house", but some prefer to keep large power drains (A/C, E/V etc.) from totally draining the battery and not having any backup power left. When the grid goes down, those circuits will stop working.
Some loads are also too big for the Powerwall(s) to support when the grid goes down, so those are left "outside the gateway" and get no power when the utility fails.
dandrewk
Active Member
Gotcha, that too.
However he has two PWs. So doesn't that add up to 14 KW hard cap? That's a ton o'juice.
@MorrisonHiker :
It worked!!! Thank you! I can see the power flow as in your screen shot above, obviously with my own numbers, and they agree with the app, with a momentary delay, maybe a second or two. And I can break the two tabs away into their own separate windows and shrink them without reducing the side of the display. Perfect!
"You may notice that the numbers don't always add up. That's because the gateway never/rarely shows the flow between the grid and the Powerwalls."
But in the case of the house, I'm drawing almost no energy from the grid, unless there's energy flowing that's not shown. And as I noted above, the Power Flow numbers add up. Only the daily totals don't. I'd expect small discrepancies because the SoC of the Powerwalls at midnight will not always be the same. But the difference would not be a lot. And with my system there should be no power flowing directly from the grid to the Powerwalls.
Okay. Thank you for the explanation. None of my loads are separate. In fact, we discovered that my fast-start compressor won't run when the grid is down and I'll have to switch it off at the breaker box in the event of a power failure. My contractor doesn't think it's worth buying a new compressor, since this is only an issue during a power outage, but recommends a slow-start compressor if I ever need to replace this one. When the grid does go down, I probably won't want to waste power on A/C so this is okay.
My two PWs combined can deliver 10 kW. I believe that's because the inverter is only 10 kW. The single PW for the cottage can deliver 6 kW because it has a 6 kW inverter. I think the 10 kW inverter was selected because that's enough to run my whole house, as long as I'm not running A/C and charging the car at 7.6 kW at the same time. When I get the NEMA 14-50 for the garage, I'll dial back the car charger to maybe 4 kW. Right now, on 120 v., it draws 1.5 kW and gets 5 miles/hour, which is too slow to make the best use of the available sunlight.
It worked!!! Thank you! I can see the power flow as in your screen shot above, obviously with my own numbers, and they agree with the app, with a momentary delay, maybe a second or two. And I can break the two tabs away into their own separate windows and shrink them without reducing the side of the display. Perfect!
"You may notice that the numbers don't always add up. That's because the gateway never/rarely shows the flow between the grid and the Powerwalls."
But in the case of the house, I'm drawing almost no energy from the grid, unless there's energy flowing that's not shown. And as I noted above, the Power Flow numbers add up. Only the daily totals don't. I'd expect small discrepancies because the SoC of the Powerwalls at midnight will not always be the same. But the difference would not be a lot. And with my system there should be no power flowing directly from the grid to the Powerwalls.
Okay. Thank you for the explanation. None of my loads are separate. In fact, we discovered that my fast-start compressor won't run when the grid is down and I'll have to switch it off at the breaker box in the event of a power failure. My contractor doesn't think it's worth buying a new compressor, since this is only an issue during a power outage, but recommends a slow-start compressor if I ever need to replace this one. When the grid does go down, I probably won't want to waste power on A/C so this is okay.
Gotcha, that too.
However he has two PWs. So doesn't that add up to 14 KW hard cap? That's a ton o'juice.
My two PWs combined can deliver 10 kW. I believe that's because the inverter is only 10 kW. The single PW for the cottage can deliver 6 kW because it has a 6 kW inverter. I think the 10 kW inverter was selected because that's enough to run my whole house, as long as I'm not running A/C and charging the car at 7.6 kW at the same time. When I get the NEMA 14-50 for the garage, I'll dial back the car charger to maybe 4 kW. Right now, on 120 v., it draws 1.5 kW and gets 5 miles/hour, which is too slow to make the best use of the available sunlight.
All Powerwall 2's have the same inverters. They are 5kW continuous, 7W peak. The thing you need to watch out for the is LRA (Locked Rotor Amps) rating on your A/C compressor. Each Powerwall can only support 30 amps, so any compressor above 60 LRA will be unlikely to work with 2 Powerwalls when the grid is down. Inverter drive, variable speed compressors are the most Powerwall friendly.
I'll take your word for this. I think I was confusing the solar side with the Powerwall side. Now when I try to remember what we were talking about I forget the details, except that it had to do with the panels, not the Powerwalls.
This sounds like what the contractor said, except that he used the term "slow-start" to make it easier to understand.
I realized that the Tesla app shows both To Powerwall and From Powerwall daily totals, so I've re-done my spreadsheet, which means the last 3 days would just confuse my numbers, so I'm starting over from yesterday, since the app doesn't give more than the present day and the previous day. I figure I need a week of numbers to mostly cancel out differences in the SoC at the end of each day, since I'm not going to get up at midnight to write those down, and the app doesn't show a graph for the Powerwall SoC, it only shows the flow and the SoC at the moment. So I'll keep entering the daily totals for a week and then see if there's still a discrepancy. I'm also going to start noting the meter reading each day.
To add a comment from my install, doesn’t everyone get the slow start box added to their AC (air conditioner here) compressor. I forget the brand name, I did make note of it if anyone cares.
The Tesla installers added this to my compressor and i assumes it’s to reduce the max current to the compressors to something the PWs can handle.
I have everything backed-up except the 100 amp HPWC circuit.
The Tesla installers added this to my compressor and i assumes it’s to reduce the max current to the compressors to something the PWs can handle.
I have everything backed-up except the 100 amp HPWC circuit.
I noticed something this morning. I got home from paddling, took my shower, and checked my power flows. The Powerwalls were full, so the solar was just producing the 300 watts the house was drawing. I turned on the A/C and it started drawing mostly from the Powerwalls even though the sun is high in the sky and bright, no clouds shading my house. Then a few minutes later the solar had ramped up to supply the A/C. Maybe the solar does not respond instantaneously. Takes a minute or a few minutes to build up when called for. ?
Or the powerwalls needed to be discharged a bit to allow soaking up the solar capacity in case your house load decreased. A little hysteresis in the box that is coordinating production to not back feed to grid.
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