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Post by EVangelist on Jan 10, 2020 9:21:22 GMT 11
Why does everything have to make economic sense? That is why we are not doing anything about climate change because it does not make economic sense at the moment and by the time it does it will be too late. If you lost the electricity grid for a couple of months (say there was a bush fire or something) that extra Powerwall would be priceless. Things need to make “economic sense” because no-one has an infinite amount of money. A Tesla PW2 costs $12.5k installed. That is not a trivial sum, and a household needs to weigh that against everything else it spends money on. If there are solutions “A”, “B” and “C” to tacking some aspect of climate change, we need to be able to work out which of those options is economically the best one, that it is the most effective for the amount of money spent. Otherwise we would potentially waste some of the finite amount of money we have on a “solution” which may not deliver the outcome we need, and then not have the money we need to implement the solution that would work better. How would that help the situation? Acting on climate change makes lots of economic sense, and that conclusion would have been made decades ago if the costs of externalities and the increasing mitigation costs the longer the delay before acting had have been properly accounted for. So the argument is not with economics, but the fact that the economic analysis has been woefully inadequate to date (and often still is) and conveniently excludes many relevant costs. That’s when governments need to step in and say although the modelling is incomplete, it is much more likely that acting will cost a lot less than not acting. Unfortunately, we don’t have one of those governments.
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Post by rusdy on Jan 10, 2020 11:56:24 GMT 11
... If you lost the electricity grid for a couple of months (say there was a bush fire or something) that extra Powerwall would be priceless. Things need to make “economic sense” because no-one has an infinite amount of money. A Tesla PW2 costs $12.5k installed. That is not a trivial sum, and a household needs to weigh that against everything else it spends money on. If there are solutions “A”, “B” and “C” to tacking some aspect of climate change, we need to be able to work out which of those options is economically the best one,... I think most of us (in this forum at least) agree that the urgency to address climate change is required, regardless what the 'cost' is (knowingly addressing it is indeed 'economic sense'). That's what I like about the project ' Drawdown'. It ranks the 'economics' in addressing climate change. For example, if we have spare money, then donate them to me (oops, I digress), instead of getting more Tesla, it would be better to throw them at non-profit organisation that educate girls (currently rank 6 th) for example. But hey, this is where psychology (or philosophy?) comes in. In saying this, if I have spare money, I can tell you for sure I'd be getting a Tesla!! Interestingly, nuclear is ranked 20 th, way ahead of Tesla home batteries at mere 77 th...
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Post by tomkauf on Jan 10, 2020 14:08:07 GMT 11
I created my own s/sheet to do the calculations, using the actual consumption data from PW2. Doing it was a lot more complicated than I initially expected, since all the power flows in and out need to be properly accounted for and mapped to the correct tariff at the time it happened, which depends on the time of day and the day of week. But I’m a bit of a spreadsheet jockey / data guy so I wasn’t going to give up.... Very cool! I'm ok at Excel etc, but that is another level. If you'd ever be interested in sharing your spreadsheet (for my personal use), I'd be happy to give you some money for it. Or if you want to keep your work private, I could pay you to use our PW2 Data and punch in a few scenarios. Knowing which 'what-if' scenario is most profitable would pay for itself. The spreadsheet in the link I posted earlier is very detailed, but it has some inaccuracies. Eg. we have 6.6kW of PV, but a 5kW Inverter. So I never know what to enter for that figure (probably a number in between). And our power usage varies - sometimes it's a day peak, sometimes a night peak. But it only has weekday and weekend options.... I see what you mean how increasing the battery size would increase the power bill. Makes sense now that you explained it, even though it's counterintuitive at first.
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Post by tomkauf on Jan 15, 2020 8:36:29 GMT 11
So we've decided to go all-in. The goal is 100% self-powered, not just feed-in balancing out grid usage. We need to get 3-Phase (currently at the maximum 10kW on single-phase = 5kW PV Inverter + 5kW PW2), and that conversion itself will cost quite a bit. So it makes no sense to only do a small upgrade, and potentially another upgrade at a later stage. 30kW is allowed on 3-Phase. But 2 Powerwalls would only be 27kWh, which isn't even a full 30kWh Leaf charge, let alone home usage as well. That won't be enough assuming work schedule doesn't allow us to charge during the day. So unless we can charge at work (no external Power Points there at the moment), we'll have to go 3 Powerwalls + 15kW of Solar (maybe 18-20kW of Panels on the 15kW of Inverter, we'll see what the installer recommends). And as brunohill said, things don't always have to make economic sense. This is for the environment. Actually, the numbers (storage vs usage) add up very well with the above system. And our area has semi-regular power outages, so that's a factor as well - we'd have zero backup with only 2 Powerwalls and an outage early morning. The percentage of grid export should also be the same or higher, since the PV and the Home Battery both triple. Currently getting 45kWh PV production on a good day. We cancelled a Tesla Model 3 reservation last year, because I don't see the value in it at that price. To me, it makes much more sense to have a used Leaf and a big solar/battery system, and have money left over .
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Post by rusdy on Jan 16, 2020 13:13:35 GMT 11
So we've decided to go all-in. The goal is 100% self-powered, not just feed-in balancing out grid usage. .... We cancelled a Tesla Model 3 reservation last year, because I don't see the value in it at that price. To me, it makes much more sense to have a used Leaf and a big solar/battery system, and have money left over . What a commitment! This reminded me the poor 'ol folks* in the country-side, who invested north of AUD50k for off-grid system (way back before Tesla). Now, Tesla made it so seamless and relatively cheap! *poor 'ol folks = the like of this one, this one, this one, any surely many more! Gone the days where you really need to geek out on battery technologies (complete with its maintenance, charge-discharge regime, etc) to go off-grid...
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Post by tomkauf on Jan 17, 2020 14:22:45 GMT 11
What a commitment! This reminded me the poor 'ol folks* in the country-side, who invested north of AUD50k for off-grid system (way back before Tesla). Now, Tesla made it so seamless and relatively cheap! *poor 'ol folks = the like of this one, this one, this one, any surely many more! Gone the days where you really need to geek out on battery technologies (complete with its maintenance, charge-discharge regime, etc) to go off-grid... Thank you. It is, but it should retain/bring more value than eg. a new car would long-term. Oh wow, I can imagine spending that much money pre-Powerwall would've been a much bigger step. Those setups look very impressive though! You're right, these days they are relatively inexpensive. Even people who bought a Powerwal-1 spent similar amounts of money and only got about 1/2 the storage capacity of a Powerwall-2. And I hadn't even thought of the maintenance involved with those batteries.
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Post by EVangelist on Jan 19, 2020 9:18:40 GMT 11
So we've decided to go all-in. The goal is 100% self-powered, not just feed-in balancing out grid usage. We need to get 3-Phase (currently at the maximum 10kW on single-phase = 5kW PV Inverter + 5kW PW2), and that conversion itself will cost quite a bit. So it makes no sense to only do a small upgrade, and potentially another upgrade at a later stage. 30kW is allowed on 3-Phase. But 2 Powerwalls would only be 27kWh, which isn't even a full 30kWh Leaf charge, let alone home usage as well. That won't be enough assuming work schedule doesn't allow us to charge during the day. So unless we can charge at work (no external Power Points there at the moment), we'll have to go 3 Powerwalls + 15kW of Solar (maybe 18-20kW of Panels on the 15kW of Inverter, we'll see what the installer recommends). And as brunohill said, things don't always have to make economic sense. This is for the environment. Actually, the numbers (storage vs usage) add up very well with the above system. And our area has semi-regular power outages, so that's a factor as well - we'd have zero backup with only 2 Powerwalls and an outage early morning. The percentage of grid export should also be the same or higher, since the PV and the Home Battery both triple. Currently getting 45kWh PV production on a good day. We cancelled a Tesla Model 3 reservation last year, because I don't see the value in it at that price. To me, it makes much more sense to have a used Leaf and a big solar/battery system, and have money left over . I’m a bit late back to this, but wow, that is quite a commitment! Is your intent to actually have the grid disconnected, or just not draw any grid power at all? The reason I ask is that because of the “long tail” that needs to be overcome to not draw any grid power at all (i.e., extended random periods where no or little solar is generated) the solar array needs to (very roughly) increase in size in proportion to the battery capacity. Increasing one or the other improves the stats, but not as much as increasing both. The issue then is that the larger solar array will spend a lot of its time generating more power than you need (even our modest array overall generates 20% more power than we consume). If you remain grid connected, you get paid for that power exported. If you don’t, that power can’t go anywhere once the batteries are full (which they will frequently be). So it becomes more than just a philosophical question but a valid financial one. I had a strong desire to go completely grid free if it was possible, but have learned lots of interesting things which changed my mind. First, for my house, it just would never be possible. I simply do not have enough roof space to generate the amount of solar that would be required to do it (unless and until panel efficiencies reach 40% or so - some time off). And now having had my system running for over 6 months, I learned a lot about the statistics of solar generation and consumption and how hard it is to chop the tail off. I’m not trying to dampen your enthusiasm, which is great, but I have discovered how devilishly complicated this is so it’s important to have realistic expectations. Every house is different, every usage pattern is different, so what I’ve learned isn’t necessarily directly applicable to others. Just some general insights which may be relevant. Good luck with your new plan, what you will find is how liberating it feels to reduce (if not eliminate) reliance on grid supply!
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Post by tomkauf on Jan 26, 2020 19:25:38 GMT 11
I’m a bit late back to this, but wow, that is quite a commitment! Is your intent to actually have the grid disconnected, or just not draw any grid power at all? The reason I ask is that because of the “long tail” that needs to be overcome to not draw any grid power at all (i.e., extended random periods where no or little solar is generated) the solar array needs to (very roughly) increase in size in proportion to the battery capacity. Increasing one or the other improves the stats, but not as much as increasing both. The issue then is that the larger solar array will spend a lot of its time generating more power than you need (even our modest array overall generates 20% more power than we consume). If you remain grid connected, you get paid for that power exported. If you don’t, that power can’t go anywhere once the batteries are full (which they will frequently be). So it becomes more than just a philosophical question but a valid financial one. I had a strong desire to go completely grid free if it was possible, but have learned lots of interesting things which changed my mind. First, for my house, it just would never be possible. I simply do not have enough roof space to generate the amount of solar that would be required to do it (unless and until panel efficiencies reach 40% or so - some time off). And now having had my system running for over 6 months, I learned a lot about the statistics of solar generation and consumption and how hard it is to chop the tail off. I’m not trying to dampen your enthusiasm, which is great, but I have discovered how devilishly complicated this is so it’s important to have realistic expectations. Every house is different, every usage pattern is different, so what I’ve learned isn’t necessarily directly applicable to others. Just some general insights which may be relevant. Good luck with your new plan, what you will find is how liberating it feels to reduce (if not eliminate) reliance on grid supply! That's ok, I'm slow as well - too many long hours at work. I hadn't planned to go off-grid. It would save the quarterly service fee though. But like you said, there will still be a LOT of feed-in, which would be lost if going off-grid. So far in January, despite having very mixed weather, it was 365kWh feed-in. Thank you for the information. Sounds like you've looked into this in a lot of detail. I'll definitely keep all that in mind. We'll wait to see if the installers say it is possible, but it should be.
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Post by tomkauf on Apr 30, 2020 17:11:27 GMT 11
This is what we ended up with. A 2nd Powerwall and another 20 Panels (330W LG) to double what we had - pictures attached. It's working well . Today was the first day they charged, so Self-Powered % is low. These new panels face South, which isn't great. But the North facing roof already has panels, and with a 3 degree roof pitch, it isn't a huge reduction. After 3 months of back-and-forth between our local Electrician, Energex, and the Energy Retailer/Meter Installer, we finally got 3-phase installed 2 weeks ago. Even things like having a few Circuitbreakers and a Powerpoint in the top 'Meter Section' of the Meter Box was flagged as a defect, which required a return visit. And the usual miscommunications, where the Meter Installer came out before Energex had connected the 3-phase, requiring another return visit. And during all this, someone not familiar with Powerwalls installed it incorrectly in the circuit. I think they said it was installed before the main circuit-breaker, which was technically another defect. Not the installers Keen2BeGreen, they were great - they fixed that as part of the install on the day. Still some painting I need to do, and sanding the patching I did, since the Powerwalls couldn't be stacked while wall-mounted. So they moved the existing one down, leaving as few holes as possible. There was also no more room on the wall outside for the 2nd Inverter, so it got installed inside.
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Post by rusdy on Apr 30, 2020 17:26:42 GMT 11
... A 2nd Powerwall and another 20 Panels (330W LG) to double what we had... Nice! I didn't know that they can be stacked that way. How did they mount it? As the front face is the shiny-face one, so surely no mounting possible? The user interface also doesn't tell much (apart from "x2"). Looks like typical Tesla, no details what-so-ever when it comes to the internal working. Typical consumer won't need those details anyway... (except me, I want to know down to each coulomb that going in-and-out of each battery cells!)
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Post by tomkauf on Apr 30, 2020 18:35:23 GMT 11
Nice! I didn't know that they can be stacked that way. How did they mount it? As the front face is the shiny-face one, so surely no mounting possible? Yeah I'd be interested to know how they are mounted as well, because I'd like to temporarily shift them a tiny bit so I can paint behind them. After switching it all off, of course. We'll see if someone has found an Installation Manual online. I originally thought they'd put the 2nd one on the opposite garage wall, since there's no room for them side-by-side on this wall (due to the window). But I'm not sure if running cables between them is feasible. This way of stacking is the official Tesla way. They sent me this Tesla press-photo to show how it'd look: www.solarchoice.net.au/wp-content/uploads/Tesla-Powerwall-2-installed.jpgBut when it was still in the planning stage, I reminded them that my first one was wall-mounted. So they decided to floor mount them now, which works fine as well. According to specs, they're 114kg each, that's a fair bit. The rear side is definitely bolted to the wall with a bracket, I can just see behind it. And they are joined with this sort of U-shaped clamp (picture attached). But I don't know how the cabling goes between them. Maybe it is made with a certain spot to drill through the shiny-face, since the inner one will never be seen. Attachments:
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Post by tomkauf on Apr 30, 2020 18:36:40 GMT 11
The user interface also doesn't tell much (apart from "x2"). Looks like typical Tesla, no details what-so-ever when it comes to the internal working. Typical consumer won't need those details anyway... (except me, I want to know down to each coulomb that going in-and-out of each battery cells!) There's a bit more detail on other pages, incl optional weekly/monthly/yearly stats. And a spreadsheet that can be downloaded (attached). But like you said, basically nothing showing the internal workings. Attachments:data.csv (8.78 KB)
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Post by EVangelist on May 1, 2020 9:03:14 GMT 11
This is what we ended up with. A 2nd Powerwall and another 20 Panels (330W LG) to double what we had - pictures attached. It's working well . Today was the first day they charged, so Self-Powered % is low. Wow that’s quite an investment! And quite some rigmarole to get them installed and power converted to 3 phase etc... I hate to think how much all of that cost!?! Let us know how it works out after a few months... I’ll be very interested to see how much you get your grid consumption down.
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Post by EVangelist on May 1, 2020 9:13:51 GMT 11
The user interface also doesn't tell much (apart from "x2"). Looks like typical Tesla, no details what-so-ever when it comes to the internal working. Typical consumer won't need those details anyway... (except me, I want to know down to each coulomb that going in-and-out of each battery cells!) There's a bit more detail on other pages, incl optional weekly/monthly/yearly stats. And a spreadsheet that can be downloaded (attached). But like you said, basically nothing showing the internal workings. Just a tip... the stats that you download from the app only reflect what you see on the screen. So, for example, if you show your monthly stats on the screen and then click on the “Download my data” button, the data that will be downloaded is the daily summary data displayed on the screen, i.e. solar, consumption, Powerwall, grid totals for each day. You don’t get the 5-minute resolution data for the entire month. This is a pain, because the only way to get and retain the 5 minute data is to manually scroll through every day in the App one day at a time and “Download my data” each time. I’m obsessive enough to actually do that, but it gets very tiresome. I am not aware of any way to automate that through the Tesla API (you can open a web browser and log in to your battery, and there is an unpublished API to send commands to it and get responses... but extracting the 5 minute data does not appear to be one of them). The 5 minute data is required if one wants to compare the costs of different grid plans based on exactly what your system has done, for example, or do “what if” calculations. I actually wrote to Tesla to point this out and said they need to have two buttons on all the Weekly, Monthly and Yearly screens. One button that says “Download summary data” which will be the data shown on the screen, and the other “Download detailed data” which will be the 5 minute data for the time period selected on the screen. I really hope they add that at some point.
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Post by tomkauf on May 1, 2020 18:27:39 GMT 11
Wow that’s quite an investment! And quite some rigmarole to get them installed and power converted to 3 phase etc... I hate to think how much all of that cost!?! Let us know how it works out after a few months... I’ll be very interested to see how much you get your grid consumption down. It is definitely not cheap. But I see people on forums getting eg. a Tesla Model 3, and I think to myself, I can't afford or justify that. With this Solar/Battery setup and a used 30kWh Leaf, we're still over $10k cheaper than the current price of a base Model 3. Car Loan Interest Rates are low these days, but our Home Loan Redraw (3% Interest) was most likely cheaper. And this solar/battery system will at least pay for a good percentage of its cost. We're definitely planning to live here for many years. It ended up being a total of $49.50/metre (incl labour) to run 3-phase cabling. But since we're semi-rural, I think economies of scale worked in our favour. I don't think eg. a 5m run would average out as cheap. The Meter Box work to relocate the Powerpoint externally and move Circuitbreakers was $181. All the Energex screw-ups were no extra (that's their problem), just wasted time. And the Energy Retailer charged $300 for the 3-phase Meter upgrade. After the installers deducted the Solar Credits, it worked out to be a total of $364.30 per panel installed incl 5kW Inverter. The Powerwall price is pretty fixed, that's the cost. Plus in our case $1100 Labour, and $850 for all the Cabling, Switches, Isolators and Transport (a fair bit of travel out to us in the Hinterland). Yeah no problem, I'll let you know. The install on Wednesday was nicely at the end of the month, so by early June we'll have a good idea of the first full month. Before we got the Leaf, we had basically zero grid consumption with one Powerwall (that's Gross, before taking into account solar feed-in). When I phoned up the Energy Retailer, they sounded very confused and asked how small the house is . I said 3 bedrooms - then he was even more confused, until I mentioned we had Battery Storage. Since then, the 3 full months we've had the Leaf (Jan-March) was an average of 153kWh monthly gross grid consumption (105, 186, 168).
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Post by tomkauf on May 1, 2020 18:29:12 GMT 11
Just a tip... the stats that you download from the app only reflect what you see on the screen. So, for example, if you show your monthly stats on the screen and then click on the “Download my data” button, the data that will be downloaded is the daily summary data displayed on the screen, i.e. solar, consumption, Powerwall, grid totals for each day. You don’t get the 5-minute resolution data for the entire month. This is a pain, because the only way to get and retain the 5 minute data is to manually scroll through every day in the App one day at a time and “Download my data” each time. I’m obsessive enough to actually do that, but it gets very tiresome. I am not aware of any way to automate that through the Tesla API (you can open a web browser and log in to your battery, and there is an unpublished API to send commands to it and get responses... but extracting the 5 minute data does not appear to be one of them). The 5 minute data is required if one wants to compare the costs of different grid plans based on exactly what your system has done, for example, or do “what if” calculations. I actually wrote to Tesla to point this out and said they need to have two buttons on all the Weekly, Monthly and Yearly screens. One button that says “Download summary data” which will be the data shown on the screen, and the other “Download detailed data” which will be the 5 minute data for the time period selected on the screen. I really hope they add that at some point. Ah yes, I see what you mean. That's a very good point - Tesla should implement that. Even though I haven't downloaded the data much in detail, I do look at it thoroughly (mostly the daily/weekly numbers on the phone). And even then, just manually scrolling through every day/week is annoying. Especially when only trying to get back to today's page. EDIT: How do we log into the Battery through the web browser? Just by entering the IP address?
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Post by tomkauf on May 2, 2020 14:34:34 GMT 11
I didn't know that they can be stacked that way. How did they mount it? As the front face is the shiny-face one, so surely no mounting possible? I confirmed that they drill through the shiny side, and have this metal pipe conduit to run cables. But apart from that, mounting between them is clean - just external brackets that clip on. The hex bolts are only for rubber spacers. The installation manual comes up when googling it. But it shows that the unit towards the wall is lifted into place. So I won't be shifting them a bit, that'd require undoing the cabling between the units. I'll do the best I can to patch and paint the big bare spot to the right of it.
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Post by rusdy on May 2, 2020 23:03:30 GMT 11
I confirmed that they drill through the shiny side... But apart from that, mounting between them is clean - just external brackets that clip on... Interesting! I thought that black looking bracket is it, assuming the shiny metal part is strong enough to hold by the edges.
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Post by tomkauf on May 9, 2020 14:58:36 GMT 11
The Tesla App has been giving incorrect readings ever since the 2nd PW & more Solar got installed. Even though the Meter shows basically 0 Grid Consumption per day (0.2 kWh in 7 days, with feed-in shown in a different menu). And the Tesla App Graph doesn't ever go above the X-axis (only below, showing feed-in). And the Tesla App 'Download My Data' shows 0 Grid Consumption (only 0, or -ve numbers for feed-in). BUT I have 2.6-2.8 kWh/day Grid Consumption according to the the number on the screen of the Tesla App. And because of that, our 'Self-powered %' is maximum of 80-90% per day . It didn't do this with only 1 PW. We had many days with 100% Self Powered. How can the Grid usage be that high if the PWs are still 50%+ state of charge? (rhetorical question). The installers contacted Tesla support twice, but Tesla say it's all working normally. Anyway, I'll just have to ignore those numbers in the app. Or I'll try contacting Tesla myself one day... Attachments:
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Post by rusdy on May 9, 2020 23:44:03 GMT 11
The Tesla App has been giving incorrect readings ever since the 2nd PW & more Solar got installed. Even though the Meter shows basically 0 Grid Consumption per day (0.2 kWh in 7 days, ... Really? Your PW2 performance is better than mine! My PW2 still importing 50 Watts per hour during peak time (according to my electrity provider's power meter). However, according to the app, it imports half of it. This figure has been consistent since the 'Time Base Control' available since mid 2018 (my blurb back then: epxhilon.blogspot.com/2018/06/powerwall-2-time-base-control-algorithm.html?m=1 ). My assumption, the electricity provider's power meter is more accurate. So, I'm a bit disappointed that PW2 doesn't suppress my grid import (during peak period) closer to zero. Because of this 'poor' performance, I get charged 14-cents (0.3 kWh) per day extra. Not happy
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Post by tomkauf on May 10, 2020 22:20:03 GMT 11
Really? Your PW2 performance is better than mine! Because of this 'poor' performance, I get charged 14-cents (0.3 kWh) per day extra. Not happy Oh wow, and I thought mine was bad . But at least our Meter shows a low consumption, even thought the App is totally wrong. When we had one PW, 0.1kWh was always the daily Grid Consumption (attached) when the battery lasted through the night. I thought it was actually 0, but I must've remembered it wrong. Which doesn't match up with the current 0.2kWh in 7 days either, especially because 2 systems on 3-phase should use more from the grid than 1 did. But from what I have read, the PW isn't very accurate at measuring consumption, because it isn't calibrated to any standard. And it can do unusual things: forums.tesla.com/forum/forums/discrepancy-between-grid-usage-reported-tesla-app-and-electricity-billsforums.tesla.com/forum/forums/powerwall-2-uses-grid-power-when-not-neededBut I guess I'm still at an acceptable actual grid consumption. Is your issue something you could log with Tesla as a fault (or at least query it)? I assume I understand our Meter reading correctly. Attached is the Meter reading on 3rd May around midday, of 171.5kWh. Yesterday (which is actually only 6 days), it was 171.7kWh. But this evening it's still 171.7. The only other menu with any figures when toggling through the Meter, is a higher value that goes up by 30kWh+ per day at the moment, which roughly matches the solar feed-in. EDIT: I read through your blurb, and Time Based Control definitely makes things a lot more complicated. Not much I can help with that unfortunately. Attachments:
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Post by EVangelist on May 16, 2020 0:27:07 GMT 11
The Tesla App has been giving incorrect readings ever since the 2nd PW & more Solar got installed... It didn't do this with only 1 PW. We had many days with 100% Self Powered. How can the Grid usage be that high if the PWs are still 50%+ state of charge? (rhetorical question). The installers contacted Tesla support twice, but Tesla say it's all working normally. Anyway, I'll just have to ignore those numbers in the app. Or I'll try contacting Tesla myself one day... First, are you operating in TBC mode or Self-Powered mode? TBC will do things like export solar to grid in preference to charging the batteries to 100%, sometimes use shoulder grid power in preference to discharging the batteries, as well as use offpeak power to charge the batteries. It uses an AI algorithm to try to minimise your “costs” but the algorithm does weird things and it’s hard to work out what it’s trying to do. I tried TBC for a few months to see what it did, and then compared it to what would have happened under self-powered mode. I decided TBC wasn’t actually saving me money (it was fairly line ball in my case) but significantly reduced my self-consumption as it shunted power between the grid and the battery trying to arbitrage price differentials. So I have reverted to self-consumption. Also, you switched to 3-phase power though as well, right? I wonder if that has screwed the App reporting up somehow.
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Post by tomkauf on May 16, 2020 14:29:49 GMT 11
First, are you operating in TBC mode or Self-Powered mode? TBC will do things like export solar to grid in preference to charging the batteries to 100%, sometimes use shoulder grid power in preference to discharging the batteries, as well as use offpeak power to charge the batteries Also, you switched to 3-phase power though as well, right? I wonder if that has screwed the App reporting up somehow. We use self powered mode (set to 10% reserve). But we haven't come near the reserve percentage since the 2nd PW install. Yes, the 3 phase connection was done around the same time. About a week earlier than the 2nd PW. But the Meter installer said the PW was connected wrong, so it was to disconnect until the 2nd one was installed. So we didn't get any performance stats while on 3-phase with a single PW. The solar/battery installer electrician also suspected it could have something to do with the 3-phase. He said it was a wild guess, but power going down 1 phase, and coming back another?
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Post by tomkauf on Jun 21, 2020 16:54:10 GMT 11
Quick update. No change to the Powerwall reading wrong, but I didn't bother reporting it again. Grid usage according to the Meter has been 11.2kWh in 7 weeks (exactly 49 days). That includes 1 day the PW2s went flat because we had to charge the Leaf more than usual overnight. The Tesla App showed ~7.5kWh more Grid Consumption that day. So without that unusual day, we would be at 3.7kWh for those 49 days (average 0.076kWh/day). I've noticed the Tesla App also reads the Feed-in wrong, since the upgrade. The meter showed 805.5kWh in those 49 days, and the App showed 943.2kWh
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Post by EVangelist on Jun 22, 2020 21:48:43 GMT 11
I recently received my first quarterly electricity bill after switching to a 21c solar feed-in tariff with a new supplier. Comparing what the bills says with what the Tesla PW2 downloaded 5-minute data reckons over the same period shows this: According to PW2 data, about 7% of my grid consumption is missing. Why the Shoulder period is out by so much is a bit of a mystery - if the PW2 measurements are out, I don't know why it would depend on the time of day. Offpeak is close-ish. I suppose the good news is that measurement of solar export is basically spot on.
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Post by tomkauf on Jul 9, 2020 1:33:15 GMT 11
Response from Tesla after my solar installer company asked if the metering problem was resolved:
I have looked into this case. Currently Gateways are experiencing net metering issues for 3 phase sites. The problem the customer is describing is being investigated by Engineering and they are working on a resolution.
The bug fix will be deployed in a FW update to the Gateway.
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Post by EVangelist on Jul 9, 2020 23:09:07 GMT 11
Response from Tesla after my solar installer company asked if the metering problem was resolved: I have looked into this case. Currently Gateways are experiencing net metering issues for 3 phase sites. The problem the customer is describing is being investigated by Engineering and they are working on a resolution. The bug fix will be deployed in a FW update to the Gateway. That’s interesting. I have 3-phase. Do you have Gateway 1 or Gateway 2? My Gateway 1 failed last week, just over a year since installation. Red blinking light, reset does nothing. The app has gone dark, no power flows reported, but at least the solar is still working and exporting (I can log into the inverter), but we have no storage. Given the rateplan we are on has eye-watering peak rates (54c) and it’s winter, it’s a bit of a bugger having no battery, because from about 3pm we are on grid. Ouch. It has been reported to Tesla but unfortunately they say it is 2-3 weeks for field service to come and fix it Part of me is hoping it is unrepairable and I get Gateway 2 replacement, but that would likely entail another 2-4 week wait.
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Post by tomkauf on Jul 11, 2020 2:49:35 GMT 11
That’s interesting. I have 3-phase. Do you have Gateway 1 or Gateway 2? My Gateway 1 failed last week, just over a year since installation. Red blinking light, reset does nothing. The app has gone dark, no power flows reported, but at least the solar is still working and exporting (I can log into the inverter), but we have no storage. Given the rateplan we are on has eye-watering peak rates (54c) and it’s winter, it’s a bit of a bugger having no battery, because from about 3pm we are on grid. Ouch. It has been reported to Tesla but unfortunately they say it is 2-3 weeks for field service to come and fix it Part of me is hoping it is unrepairable and I get Gateway 2 replacement, but that would likely entail another 2-4 week wait. We have a Gateway 2. Ah ok, shame your Gateway failed so soon :/. We must have gotten one of the first Gateway 2s, if you got your GW1 just over a year ago. 18th July 2019 is the first day ours showed any data, so it would've been around that time we got ours. And it's definitely worse because of your very high peak rate. But fingers crossed you get a whole unit replacement and all they have available are GW2s. I'm not sure if there are any advantages to a GW2 in terms of performance, but they definitely look better .
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Post by EVangelist on Jul 11, 2020 13:14:23 GMT 11
We have a Gateway 2. Ah ok, shame your Gateway failed so soon :/. We must have gotten one of the first Gateway 2s, if you got your GW1 just over a year ago. 18th July 2019 is the first day ours showed any data, so it would've been around that time we got ours. And it's definitely worse because of your very high peak rate. But fingers crossed you get a whole unit replacement and all they have available are GW2s. I'm not sure if there are any advantages to a GW2 in terms of performance, but they definitely look better . Our system was commissioned early May last year. Our installer said if I was desperate for Gateway 2 I would need to wait about 2 more weeks and they would have the first units in Australia. I was tempted, but elected to proceed with the install as planned, because it was part of a larger house renovation and I didn’t want to upset the scheduling of other work. Gateway 2 has better 3-phase compatibility. On 3-phase supply, Gateway 1 will measure the house draw on all 3 phases, and if there is solar excess, it will inject the excess back into the grid but only into Phase A. My understanding of Gateway 2, however, is that it will inject the solar excess into all 3 phases. In billing terms it makes no difference (total grid draw is the same) but it’s much better for the power companies as it assists in maintaining phase balance. Let’s say the house is drawing 5A on Phase A, 3A on Phase B, and 2A on Phase C, and solar is generating 5kW (20.8A). Total consumption is 10A or 2.4 kW and solar excess is 2.6 kW (10.8A). With 1 Powerwall and 1-phase inverter, the draw on Phase A (5A) is fully covered by solar but I am still drawing 5A from the grid in total across the other 2 phases. With Gateway 1, it will inject 5A into the house (Phase A) and the 15.8A left over goes into the grid but on Phase A only. So from a metering perspective, Phase A is -15.8A (since there is no grid draw on Phase A, it is all covered by the solar), Phase B is 3A and Phase C is 2A. Add that up and net export is 10.8A as it should be. But you can see from the power company’s perspective, that’s not particularly nice. With Gateway 2, it will still inject 5A into the house (I don’t think it can drive all 3 house phases?) but the 15.8A excess will be injected into the grid across all 3 phases. I don’t know if it just shares it equally (-5.3A per phase) or whether it tries to pro-rata based on actual consumption per phase. I suspect the former. But if I’m wrong happy to be corrected With 3xPowerwall and Gateway 2, I assume it can drive and back up all three phases of a house.
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Post by tomkauf on Jul 11, 2020 21:05:38 GMT 11
Our system was commissioned early May last year. Our installer said if I was desperate for Gateway 2 I would need to wait about 2 more weeks and they would have the first units in Australia. I was tempted, but elected to proceed with the install as planned, because it was part of a larger house renovation and I didn’t want to upset the scheduling of other work. Gateway 2 has better 3-phase compatibility. On 3-phase supply, Gateway 1 will measure the house draw on all 3 phases, and if there is solar excess, it will inject the excess back into the grid but only into Phase A. My understanding of Gateway 2, however, is that it will inject the solar excess into all 3 phases. In billing terms it makes no difference (total grid draw is the same) but it’s much better for the power companies as it assists in maintaining phase balance. With 3xPowerwall and Gateway 2, I assume it can drive and back up all three phases of a house. Ah ok, 2 weeks isn't a long time, but not really worth delaying major renovations for. Makes sense, that is a difference that's worth something to the power companies. But no difference in billing terms like you said. 3xPowerwalls would be the dream . Since our house was originally built for single-phase, I don't think we'd have any advantage in terms of backup (just total storage capacity). But being able to have more solar - a limit of 5kW Inverter and 1 Powerwall per phase was why we had to go 3-phase.
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