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General Renewable Topics => General Discussion => Topic started by: dickster on January 11, 2019, 11:40:08 AM



Title: Tesla Powerwall 2, one month in.....
Post by: dickster on January 11, 2019, 11:40:08 AM
Hi there, hope I'm not treading on Navitron's toes!.

I did what I could to research the PW2 before stumping up the dosh for one, but basically took the plunge a month ago along with a 2.3 kWp 7 panel array. Thought I'd post this as it might help others to decide whether or not to do same (other similar products are available!).

So install in shed seemed good, but couldn't get Tesla app to work properly. Tesla customer service is cr*p, no returned calls etc, but installer came out quick as they could, apologised and put one of the CT clamps on the right cable!. This grey area, with the installer not responsible for my downloaded app and Tesla not responsible for the install means that the buck could be passed back and forth ad infinitum.

The Tesla app was then able to work properly, if intermittently, but not too easy to use as a tool, rather than just using it as a monitoring device.

You can set it to use solar generated during day at night. (default setting)

So we started off at around 15% SOC, but dull weather meant we were quickly slipping downwards and my overall plan was to almost fully charge and then fully discharge the PW2 on a regular basis to keep those batteries healthy. Until summer comes along I knew we wouldn't be able to do so just by using solar, so I started poking around in the customise settings.

You can change it to charge from the grid in two modes, one in economic mode to maximise savings (using Economy 7 or the like), or one in a more greener mode. These allow you to set the times when you want the battery to charge from the grid.

What you can't do yet is set SOC switches, for example, only charge to 50%, discharge to 30% etc. However, you can do this by calculating how long it will take to charge to a set percentage, ie 3.5 kW charge rate X 2 hours = 7kWh = 50% increase in SOC. and set the timing appropriately. (All approx, hope nomenclature is correct!)

I've only just started doing this, but great to see it start and stop charging when told to. It does mean that you might have to twiddle about every day with settings, great fun at the moment, but probably a bit tiresome after a while.

In other countries PW2 can be used as backup in a powercut, not so in UK , as the Tesla Gateway (control box thingy on wall)  has not been accredited for this yet. Also rumoured to be in the pipeline is a weather forecast for your area software upgrade, no need to charge overnight if tomorrow is going to be a sunny day type of thing.

We've got satellite broadband and only switch it on when we need it (40W per hour), and I was told it would work without continuous connection. Importantly it does, but Tesla require some connection every now and then, and of course, Tesla now can control my battery any time they want to without referring to me (just like Windows 10!).

The app (I think) only works on not too old mobiles and tablets running android or Apple, you can't run it on a windows laptop etc. which is a bit of a shame.

The Gateway emits a wi-fi signal which I have managed to pick up on my old tablet (which won't run the full app) and so a passive display of energy flow can be displayed without having the internet on. V pleased about that.

At the moment I'm pretty happy with the PW2, but will update stuff if as and when it might be useful.

I hope this info is of interest.







Title: Re: Tesla Powerwall 2, one month in.....
Post by: M on January 11, 2019, 11:59:59 AM
Thanks. All info on battery experiences is appreciated. I'm watching and waiting ..... impatiently.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dan_b on January 11, 2019, 02:00:43 PM
Where in the country are you? You might find that your 2.3kWp array will struggle to give you a full battery charge for most of the year given how large the Powerwall 2 is in kWh terms?
Do you have a solarEdge PV system as I understand they can integrate pretty closely with the Powerwall for the software?
Great to know about another battery owner though, keep the info coming.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: azps on January 11, 2019, 06:31:45 PM
my overall plan was to almost fully charge and then fully discharge the PW2 on a regular basis to keep those batteries healthy.

Umm, are you sure that will work?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 14, 2019, 10:33:41 AM
Hi Dan B,

I'm in Hampshire and have a very useful local array that is on PV output. This has allowed me, along with PVGIS, to estimate annual and seasonal generation. Should have no trouble during summer months in living of the sun, winter will need a charge cycle approach. I do have Solaredge on there, as we have shading ( sun low through winter trees) and bird poo problems.

azps It's sort of working, charged on Friday night to last the weekend, but all sorts of anomolous readings on the Tesla app when electric oven was on last night. Can't be sure if it's the battery, the sensors or the app.
Plan to do the same, but take note of meter reading to see what is what.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: russ_fae_fyvie on January 14, 2019, 10:42:01 AM
Thats great to get your experiences because I placed an order for a PW2 along with a 4kW PV Array for our new build !

Had been wooing and froing for ages and finally decided on the PW2 after visiting the Installers who seem pretty good (hopefully!) but its good to see someone on here who has one in operation so many thanks for your experiences so far.

Ours aren't due to be installed until the kit goes up in (hopefully) April/May so will be watching your further comments !!


www.stationbrae.uk (http://www.stationbrae.uk)


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dan_b on January 14, 2019, 11:39:53 AM
Russ - you do know that the FiT/Export tariff is being scrapped completely in April, so if your install goes in after then you'll not receive any of the payments for solar generation that you might have expected?  Might want to prioritise getting the array up and running well before then if you're budgeting on receiving those payments for what you generate?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: russ_fae_fyvie on January 15, 2019, 08:25:57 AM
Hi Dan,
No hadn't budgetted on any FITs, we know from the last house at Long Rig, the FITs were pretty cr*p towards the end and that they were being scrapped in April, only using MCS stuff now because we are applying for the Interest Free Loans for the PV/Inverter and ASHP but as usual, after applying they are now dragging it out by asking daft questions !!


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Sprinter on January 15, 2019, 09:38:58 AM
as for the application, it might not be PC compatible but that isnt a problem, just install a "BlueStacks" or other android emulator on your laptop and there you have it.

Old phones are no longer an issue


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 15, 2019, 10:46:49 AM
Hope it's Ok to update often whilst things are fresh in my mind.

So after the Tesla app went wild on Sunday evening with the oven on, (showing flow from grid to house, battery to house and even solar to grid, (in the dark!)), I had a good think. The internet connection was off during this time, when flow should just have been from battery to house, so last night (baked potatoes) I tested it again. Plenty in battery, internet on, meter read. It worked perfectly, with electric kettle on top showing max flow from battery and additional from grid. Then I switched internet connection off, it still showed correct flow on Gateway wi-fi.

There are quite a few complaints out there of anomolous behaviour. Next test would be oven on but internet off before starting to see if I can replicate Sunday's oddness.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: russ_fae_fyvie on January 15, 2019, 01:36:24 PM
We've got satellite broadband and only switch it on when we need it (40W per hour)

I meant to say, we don't have a landline in the rented place we are in and we aren't installing a landline in the new house either.

With that in mind I checked satellite phones but cost was horrendous and the ping times were no good, so I bought a Mobile Wi-Fi Router that just runs off a Data Sim (EE for me) and its brilliant, can leave it on all the time and we have much better speeds than we had at Long Rig from BT's landline (up to 70mbps compared to 5 to 8 max on the BT line). Also use it for Netflix, Amazon streaming, etc and its great.

Just a thought if you are finding the Sat Phone has cost and speed restrictions.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 21, 2019, 10:09:25 AM
Next experiment, internet on, charge Powerwall 2 from mains for 2 hours beginning Friday 23.30 ending Sat 01.30 am. Should add approx 7 kWh. Didn't stop charging because there is a weekend setting that I had not done a setting for. I stopped it by changing the setting to default (no charging from mains), lesson learned.

Sunday lunchtime, internet off, set on default and has 60% SOC. With washing machine on and intermittent bright sunshine, watched the flow chart on Gateway wi-fi. Throughout the wash, all flows made sense, apart from occasional flows to and from grid of up to 10 secs a time, however these were shown as  0.1 (+/-) or much less often 0.2 kW. Too small to be measured by reading the meter, I'm guessing that these are anomolous flows shown when the Gateway does it's sums, which are rounded up or down (who knows?) to the nearest 100 Watts. Satisfactory, with 61% SOC after wash. All this done with no internet, v good.

I'm a bit of a Tesla watcher and with recent news of layoffs dividing the financial boys 50/50 bankcruptcy/sensible long term measure, I got to wondering, what happens if Tesla goes bust?. No way to control my battery, hadn't really thought about it before. Perhaps something to worry about or at least consider if you might fancy getting one.

One thing that is a bit mystifying, I can't seem to find any information on the workings of PW2. Normally someone somewhere has done a "tear down" to show the innards and explain a thing or two, I'd also like to know how and when it communicates with the Tesla servers, but can't seem to find anything much out there.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dan_b on January 21, 2019, 10:32:44 AM
Everything you need to know about PowerWall 2

https://cleantechnica.com/2019/01/19/everything-you-need-to-know-about-the-powerwall-2-2019-edition/


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 21, 2019, 02:49:04 PM
Thanks, Dan B,

It's good to get a look inside, lot's of the info doesn't pertain to the Uk yet, but still very useful.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: andrewellis on January 21, 2019, 08:31:20 PM
Hi Dan,
No hadn't budgetted on any FITs, we know from the last house at Long Rig, the FITs were pretty cr*p towards the end and that they were being scrapped in April, only using MCS stuff now because we are applying for the Interest Free Loans for the PV/Inverter and ASHP but as usual, after applying they are now dragging it out by asking daft questions !!

They may not be great but would still add up to in the region of 4000 over the 20 years.  That's a good chunk of the panels cost.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 23, 2019, 03:15:37 PM
So to sum up. I'm happy now that I can control the SOC of the PW2 using the Tesla app, thus avoiding leaving it discharged for long periods of time in dull weather.

I'm also very happy that on a sunny January day (today), the system has generated over 60% (3.5 kWh) of our average daily usage, with the excess tucked away in the PW2 for use later on this evening.

I now intend to get a quote for an Economy 7 meter ( I have a cunning plan....), but remain very aware that a trip through a PW2 costs 10% of the electrons.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: linesrg on January 23, 2019, 04:52:49 PM
dickster,

I'd consider 10% more than acceptable. When I make calculations for such devices I allow 10% each way............

Regards

Richard


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 24, 2019, 09:55:52 AM
Another point. Below freezing this morning, what has the PW2 done to look after it's batteries? Warmed them up with 300W at 4 a.m. this morning.

Cheeky, but good to know it's looking after itself without me having to fiddle about.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: oliver90owner on January 24, 2019, 11:09:53 AM
For how long was it warmed and how cold was it?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 24, 2019, 12:17:14 PM
The app is not accurate enough to give good readings (slidy finger over rough graph), but I reckon maybe half an hour, ramping up to a peak of 300 Watts and then back down again. Most likely a lot less than 300Wh , but gave that figure as I'm a lazy boy.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 24, 2019, 12:18:08 PM
Sorry, forgot to say -3 C.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Tiff on January 24, 2019, 01:39:23 PM
Sorry, forgot to say -3 C.

Do you know what temperature the bateries are at and what the target temperature is?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Scruff on January 24, 2019, 02:05:55 PM
What happens when the battery is too discharged to run it's electric blanket and starts charging? I suppose it must prioritise the heater and stay in a discharged state?

Is the 10% round trip losses  figure a marketing number or based on independent metering in real world conditions?

For any energy storage system <20% would be unheard of (NOC)


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 28, 2019, 10:44:28 AM
Tiff...I don't know,

Scruff, the PW2 took a charge from the grid to look after itself. The 10% is a figure that came from general chit chat amongst Tesla PW2 on the internet. A pinch of salt might be needed.

As time goes on I'll be able to narrow down all figures more accurately and might have more useful information to hand.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 29, 2019, 02:55:16 PM
With internet off, a lovely sunny day, got 4.2 kWh solar, but PW2 from 0% SOC then stopped charging from solar at exactly 12 noon with plenty of capacity left, the rest of generation exported to grid. Answers on a post card please.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on January 30, 2019, 10:18:14 AM
So overnight with the PW2 at 0% SOC , -2C and internet off, it stirred itself using 300W of mains electricity at around 2 am.

The app gives running totals for day, week and month, but doesn't store anything beyond this.

I looked at the weekly figures of consumption using the app. It stored 9.1 kWh and gave back 5.9 kWh, so my 10% loss is looking very doubtful, more like 33.3%, which is pretty awful, IF the figures are to be believed.

I suspect that running the PW2 from 0%, loading an average of maybe 1kWh of solar per day, using it at night back down to 0%, all in cold weather is perhaps the most inefficient way of power transfer.

However, the monthly totals, which include me charging fully from the grid on a couple of occasions over a period of warmer weather (less overnight stirring) show 73.2 kWh in and 62.2 kWh out, but I'm not sure what the SOC was to start with. Nevertheless it equates to around 85% efficient, so a more acceptable loss.

There are too many unknowns and it's too early in the day to be really conclusive.

Unfortunately, I am not willing to leave the satellite broadband on all the time, which would remove one of the most obvious dodgy variables from the equation.

Thanks for the suggestions for running android on my laptop, internet alternatives and all the other hints, tips and questions.




Title: Re: Tesla Powerwall 2, one month in.....
Post by: Tinbum on January 30, 2019, 11:34:50 AM
My Growatt runs at about 85% efficiency which seems to be the norm. In this cold weather though it shuts down due to battery temp and it doesn't have a heater in it. I've just bought a small 120w tube heater to fix under the battery that I can turn on with an app when needed.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: sbchapman on January 31, 2019, 03:49:54 PM
@Tinbum - that's a great idea.

'Energy for free', sort of, or at least energy enhancement ....

AC heater, powered by the battery overnight (PV in daylight), which warms the battery resulting in better energy capacity for other loads. I've been thinking about battery here but no space internally (that SWMBO would approve anway) and really wasn't keen on putting one outside due to temps, but guess you could build an insulated container outside. Will have to check the installation requirements for LiFEPO4 chemistry from the manufacturers.

However if the container were insulated, would also need a fan for cooling in summer, so one of those controller recently shared with heat and cool circuits would work perfectly ...


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 04, 2019, 10:01:54 AM
Nearly 2 months now, but should have said energy, not power, in last post.

So, PW2 has had another fit on Thursday, under the same circumstances as it's first one.

Bright sunny day, plenty in the battery, put washing machine on, crazy powerflow on the app, basically taking about half the energy from the grid, half from the battery in random seesaw wave pattern making no sense at all, but again, the internet was off. Maybe the PW2 needs to phone home during this type of usage. I'll try again when I have same conditions, but with internet on.

So Saturday, a beautiful day, full sun, pv generated 4.7 kWh and minus house usage, left with 18% SOC (on local gateway app, shows as 13% on app via Tesla). Looked forward to another sunny day on Sunday, hoping to have bridged from one day to another to another without using grid. Internet off overnight.

However, -5C overnight, PW2 didn't stir itself and even with internet on, it won't discharge, house power coming from grid. About 9 am, it started whirring and humming (as it does when it stirs itself), but still no action. Lovely sunny day, but the PW2 won't discharge or charge, now exporting sun power to grid. Nothing seemed to wake it up, so switched off Gateway for a couple of hours and then back on. As the sun went down behind the trees around 4 pm, PW2 starts discharging and feeding the house. So now it will give, but will it take? Down to 0% SOC so decide to give it 2 hours charging from 12 pm to 2 am. It starts charging as requested. Then internet off to see if it will switch itself off at 2 am.

Monday morning, internet on, good news, it charged for 2 hours. Now have to switch it back to self powered to see whether it will discharge and feed the house. More good news, it does.

So it would appear that, for one reason or another, a minus 5 C with internet off overnight is to be avoided, seemingly taking all day to defrost?, but I will be leaving the internet on next time we have a -5 C night to see what happens.




Title: Re: Tesla Powerwall 2, one month in.....
Post by: dimengineer on February 04, 2019, 10:10:06 AM
Just as a thought - so many things these days "need" the Internet to function properly that having the Internet off screws with the Powerwall's brain.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Westie on February 04, 2019, 11:24:12 AM
Just as a thought - so many things these days "need" the Internet to function properly that having the Internet off screws with the Powerwall's brain.

Thats very true. we purchase these 'must have' IoT devices now and we may still enquire about 'Warranty' but how many of ask for how long the cloud based server be maintained that providing most of the 'smart' functionality.   It's something that consumer legislation has yet to address........  How many manufacturers will use that server power switch as a way to boost sales for the next generation product ? 



Title: Re: Tesla Powerwall 2, one month in.....
Post by: sbchapman on February 04, 2019, 02:40:34 PM
Listened to a bit of "Start the Week" on R4 this morning. Very interesting piece on surveillance capitalism and references to Nest: apparently, effectively you need review 1000 privacy contracts to understand where the data from it will  be used ...


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 07, 2019, 10:40:34 AM
So the Tesla is behaving itself generally, now Solaredge is being naughty. A couple or 3 times I've had to reboot after a comms issue and all was well, now for the 2nd time I have a LAN disconnected message. Last week it fixed itself after a couple of days, this time the installer emailed to see what was going on as 3 days of no generation was being reported. The PV and Solaredge are all working perfectly well on the generation side of things.

I've reported back explaining the LAN disconnected issue. It uses the same cat5 cable as the Tesla, which continues to communicate normally. No doubt it is my 2 or 3 times a day switching the broadband off that it doesn't like, but we shall see.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 20, 2019, 10:00:46 AM
So, now I've got a Powerwall 2 that I can tell when to charge from the grid, it makes sense to get an economy 7 type meter installed. Recently moved to Ecotricity, told that I can have an E7 meter, but not an old type, will have to be a Smartmeter. I say we haven't got mobile phone reception, they say, Ok you'll have to give us the monthly readings. I say OK. Will be fitted this afternoon.

Never thought I'd be getting one. Let's see what happens.....

Result!

Meter man turned up, says there's no phone signal, why do I want a smartmeter? I say I don't, but I'm told that that's all that is available. He says he's got a brand new old style digital meter in van. One phone call and hey presto!, Stupidmeter is installed.

Good bloke, who then states the obvious. E7 Smartmeter needs to phone home to know what the time is, so wouldn't have worked anyway.

Interestingly, the new meter's clock is 30 minutes fast. Set the Powerwall for a 2 hour charge (6.8 kWh) from 1-3 am. (cloudy today). All worked well.

Solaredge comms still out, but otherwise working just fine.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 22, 2019, 10:34:07 AM
So now charging PW2 from off peak as and when necessary.

Based on using 2000 kWh per year, the rounded up approx and very simplistic forecasted sums are as follows.

4 months darkest time, use 3 kWh from off peak per day average @10p per unit = 36.00  (probably more than this)

365 days @ 0.35 standing charge (ouch)                                                   = 127.00

VAT @5%                                                                                                =8.00

TOTAL                                                                                                   171.00

2000 units @3p per unit FIT                           = 60.00

1000 units deemed export @ 5p per unit           = 50.00

TOTAL                                                        =110.00

Difference = 61.00 annual cost, a quid a weekish.

Prior to install of PV and PW2, annual cost 480.00 (Ecotricity estimated), rose tinted glasses savings per year 400.00.

Cost of installation, c/o dead friend's legacy, 11,500.00. Sunpower 2.33kWh, Powerwall 2, Solaredge.

Payback time (nothing goes wrong, still alive at the age of 92), 29 years.

But at least we got on and did, time's running out!



Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on February 22, 2019, 11:33:10 AM
Keep the updates coming Dickster, I'm waiting for my Powerwall to be delivered so good to see what it is like to have one.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 22, 2019, 11:59:37 AM
Forgot to add that I'm leaving satellite broadband on 24/7. This seems to have helped the PW2 settle down, but at the cost of 1 kWh extra consumption per day. Doh! might go back to bad old habits when the dust has settled to see what happens.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Scruff on February 22, 2019, 05:50:29 PM
Figures may vary when corrected for actual efficiency and power consumed as an atmospheric heater...


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on February 25, 2019, 09:58:02 AM
Figures definitely may vary!

So, a gorgeous weekend of sunny weather, maximum yesterday 8.9 kWh, with sun now just skimming tops of trees. Used electric oven (roast lamb), did 2 loads of washing. Battery at 30% SOC this morning, guessing +8 kWh in, maybe 6 out, expect SOC to be around 45% tomorrow morning. With sunshine forecast to Wednesday, might have a full battery for when dull hits us on Thursday. Perhaps I'll try reducing energy hungry practices ( bowls of soup, dirty clothes, etc. :))over this dull period to see how long we can last.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 01, 2019, 09:53:10 AM
So end of sunny weather, averaged 8.8 kWh generation over last few days, brilliant! It's forecast cloudy today (Friday):

Last night, 8 pm, set the PW2 (around 40% SOC) to load 1.5 hours of off peak electricity overnight and 2 hours per night for Saturday and Sunday. (We're away, dog sitters at home)

Problem. House starts using peak grid electricity immediately, should be using battery. Fiddled about, couldn't stop it. Decided to wait awhile, as other users have said that it can take up to a couple of hours to actually   start using the new settings. It paid off, after using 400 Wh of peak, it went back to using battery power and then successfully charged as instructed.

I've no idea why it did what it did.

Off to the Isle of Wight in a bit, plenty bad weather for return ferry trip on Sunday. :(



Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 04, 2019, 09:55:53 AM
Ferry back was fine :D,

Whilst on the island, used the Tesla app to check on battery, noticed that our dog sitters got up and made a brew at 7.05 am as evidenced by the peak in usage graph.

So that's how private having a Powerwall 2 is....NOT! ???


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 13, 2019, 10:15:01 AM
10 weeks into the year and, as secretly hoped, we are now going along without using the grid (bright one day, dull the next, Powerwall 2 allowing us to bridge the gap) with the sun now spending the majority of the day above tree tops. No doubt it will now rain for a fortnight!

The PW2 is behaving itself, I would give it 8 out of 10. Suspect efficiency is well below my initial assumption, maybe 75%, will report back after a more in depth work through.

One worrying thought. What happens if and when Tesla goes bust?!



Title: Re: Tesla Powerwall 2, one month in.....
Post by: RIT on March 13, 2019, 10:50:15 AM
10 weeks into the year and, as secretly hoped, we are now going along without using the grid (bright one day, dull the next, Powerwall 2 allowing us to bridge the gap) with the sun now spending the majority of the day above tree tops. No doubt it will now rain for a fortnight!

The PW2 is behaving itself, I would give it 8 out of 10. Suspect efficiency is well below my initial assumption, maybe 75%, will report back after a more in depth work through.

One worrying thought. What happens if and when Tesla goes bust?!


As the PW2 has a 10 year warranty it is worth checking the paperwork to see if the warranty is backed by a third party.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 13, 2019, 11:47:16 AM
Not too bothered about warranty, it seems like a cracking bit of kit. More concerned that if Tesla goes down, so will their servers and I will not be able to control PW2 using phone app.

Also don't understand the following. 7 Sunpower panels rated 333 Whp each, = 2.331 kWhp for system. I presumed this would be attained on the sunniest day in mid summer, but I have already got to 2.3 kWhp on a couple of occasions. Don't understand. ???


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Tinbum on March 13, 2019, 11:50:27 AM
The colder the panel the higher the output.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: andrewellis on March 13, 2019, 12:54:33 PM
 freeeze
Not too bothered about warranty, it seems like a cracking bit of kit. More concerned that if Tesla goes down, so will their servers and I will not be able to control PW2 using phone app.


https://github.com/vloschiavo/powerwall2 There is an api reverse engineered already it would appear.  It probably wouldn't take fans long to put together a replacement.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on March 13, 2019, 01:17:33 PM
Also don't understand the following. 7 Sunpower panels rated 333 Whp each, = 2.331 kWhp for system. I presumed this would be attained on the sunniest day in mid summer, but I have already got to 2.3 kWhp on a couple of occasions. Don't understand. ???

Hi Dickster

You will get less than the rated output in summer because as the panels heat up in the summer sun their output drops. You are more likely, as you have seen, that the panels will output at or slightly above their rating on days where it is cold but bright sunshine especially if there are some clouds as the panels cool when in shade but when suddenly exposed to the full sun their output will jump.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Scruff on March 14, 2019, 01:32:24 AM
The cells are rated at 20C. If you put them in a glass panel pointing at the sun they are usually 50C above atmospheric temperature. Hence their rated output is rarely ever met.

Oh but but I've seen 110% output...that's because windchill + >1000W/m input...


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 15, 2019, 09:45:02 AM
Thanks for the explanations, can't quite believe that the makers of panels don't optimise their testing results to the absolute max, but I guess there's some sort of standard they all have to follow.

Powerwall 2 misbehaving as I switch to "charge overnight from grid" settings (then internet switched off, router in spare bedroom, visitors not happy with blue flashing lights all night!), but now settled down again.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Countrypaul on March 15, 2019, 11:15:54 AM
Thanks for the explanations, can't quite believe that the makers of panels don't optimise their testing results to the absolute max, but I guess there's some sort of standard they all have to follow.

Powerwall 2 misbehaving as I switch to "charge overnight from grid" settings (then internet switched off, router in spare bedroom, visitors not happy with blue flashing lights all night!), but now settled down again.

Have you looked at your router settings? Some routers allow you to turn the LEDs off so as to prevent problems with stray light.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 15, 2019, 11:56:38 AM
Never occurred to me, I'll have a look later on. Thanks!


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 21, 2019, 09:44:19 AM
So, with this dull weather, I'm regularly charging the Powerwall 2 on E7 overnight, judging how much I need to avoid peak time mains usage the next day, but leaving spare capacity should the sun come out.

Interestingly, and regardless of SOC, if I set it for say, a 2 hour charge, it charges fully for the first hour and then tapers the charge in 3 steps down to 0 over the next hour.

Last night I set it for 3 hours and it charged fully for the first 2, then tapered the charge to 0 over the last hour.

This seems to be a new happening, perhaps Tesla have updated the software?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: sam_cat on March 21, 2019, 12:42:07 PM
Thanks for the explanations, can't quite believe that the makers of panels don't optimise their testing results to the absolute max, but I guess there's some sort of standard they all have to follow.

Powerwall 2 misbehaving as I switch to "charge overnight from grid" settings (then internet switched off, router in spare bedroom, visitors not happy with blue flashing lights all night!), but now settled down again.

Have you looked at your router settings? Some routers allow you to turn the LEDs off so as to prevent problems with stray light.


Or some black insulation tape..


Title: Re: Tesla Powerwall 2, one month in.....
Post by: rogeriko on March 21, 2019, 08:05:21 PM
The cells are rated at 20C. If you put them in a glass panel pointing at the sun they are usually 50C above atmospheric temperature. Hence their rated output is rarely ever met.

Oh but but I've seen 110% output...that's because windchill + >1000W/m input...

Solar Panels all have a NOCT output published in their documentation. That is Normal Operating Conditions and Temperature. It is considerably less than the theoretical output.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on March 29, 2019, 10:04:03 AM
Black tape, never occurred to me, wood for the trees etc, ta!

We're generating around 11kWh per fully sunshiny day and haven't used the grid at all for 5 days and have exported 3kWh. So far so good, easy to forget everything is running on sunshine thanks to all those clever people who developed this technology.

Electric car is the next step, but we have to cross our ford twice a day, anybody heard of a waterproof EV?  :)



Title: Re: Tesla Powerwall 2, one month in.....
Post by: kristen on March 29, 2019, 10:54:48 AM
anybody heard of a waterproof EV?

Not recommended, but you can get traction from spinning wheels once it starts floating ...

www.youtube.com/watch ?v=cBYFo6fXPvU

:)

Assuming all waterproofed, as it is supposed to be ... then with EV you haven't got the worry of water flowing back up the exhaust into an ICE engine etc.

EDIT: This might be a better link, as links to YouTube appear to be blocked?
https://www.wired.co.uk/article/tesla-elon-musk-model-s-drives-in-water


Title: Re: Tesla Powerwall 2, one month in.....
Post by: stucou on March 29, 2019, 11:49:38 AM
"anybody heard of a waterproof EV"

Rivian pickup EV spec 1m wading depth recent vid on Fully Charged


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on March 30, 2019, 12:56:58 PM
Hi Dickster

It's just less than 1 week since my PW2 was installed and the results so far have been really good. From midnight on Sunday till 13:00hrs today we have only imported 3 kWh from the grid.
It has caused a bit of confusion to my PV diverter as it saw the battery and "diverted" power from it during the night, a small change to the programming of the diverter has solved that problem.


Looking forward to far lower electricity bills from now on!


Title: Re: Tesla Powerwall 2, one month in.....
Post by: pantsmachine on March 30, 2019, 01:52:31 PM
Nice to see you are liking it. I was pleasantly surprised when my batteries discharged in daylight hours for the first time to support house demand when in excess of solar supply uat that point in time. Hitherto I had been thinking in darkness supply terms.
4.7 kw purchased in last week with yesterday at 0.12kW being the winner of the week!


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on March 30, 2019, 06:05:13 PM
Been watching it on the app and have seen the battery seamlessly supply power when the PV drops due to passing clouds.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on April 01, 2019, 10:35:44 AM
Hi Fintray and P*ntsmachine,

Good stuff, the last week have exported 9.8kWh and imported 0.8 kWh.

2 things to mention. One is that my Powerwall won't supply at a rate more than 3.8 kW, so oven on and kettle on with good SOC, still pulls a bit from the grid, albeit for short periods.

Also, the PW2 seems to use the grid very briefly when switching from supplying to charging or "waking up" etc. Disconcerting at first when you see the app showing grid usage when it shouldn't.

 :)



Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on April 26, 2019, 05:13:17 PM
That's just over a month since the PW2 was installed and apart from the initial problem with the PV diverter seeing the battery as exporting power (it can swing a couple of watts or so to export), sorted that by increasing the export minimum before the diverter starts diverting. In the last 31 days my consumption from the grid works out at 8.6kWh.
I can also confirm that the export limitation on the two SolarEdge inverters works just as it should as can be seen by the attached graph which shows the limitation kicking in.



Title: Re: Tesla Powerwall 2, one month in.....
Post by: linesrg on April 26, 2019, 06:34:58 PM
Ian,

I can only dream of such a low import figure... :(

Regards

Richard


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on April 26, 2019, 06:58:45 PM
Ian,

I can only dream of such a low import figure... :(

Regards

Richard

Richard

I'm hoping it stays pretty low throughout the year as the savings in import are going part way to paying for it!
Just remembered that you have the GSHP to run as well so wouldn't expect you to get a really low import although your recent upgrades will certainly help bring it down a bit more.


Regards

Ian


Title: Re: Tesla Powerwall 2, one month in.....
Post by: pantsmachine on April 27, 2019, 09:56:49 AM
Hi Fintray and P*ntsmachine,

Good stuff, the last week have exported 9.8kWh and imported 0.8 kWh.

2 things to mention. One is that my Powerwall won't supply at a rate more than 3.8 kW, so oven on and kettle on with good SOC, still pulls a bit from the grid, albeit for short periods.

Also, the PW2 seems to use the grid very briefly when switching from supplying to charging or "waking up" etc. Disconcerting at first when you see the app showing grid usage when it shouldn't.

 :)



I have seen similar at ours re peak discharge and momentary insensible draw from grid. I guess it's all down to the algorithm  which is not tweak able by lowly mortal such as myself  in the case of our Goodwe charge controller and possibly your power wall? We still try to do all the high load stuff thru the day and stagger it if possible, no great hardship for the results! :)
 This last  7 days (in no way a black catting attempt) have seen a grid draw of 0.6kwh and I am now tempted to add one more battery just for the damn of it!


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Bikerzz on April 28, 2019, 07:57:27 AM
my overall plan was to almost fully charge and then fully discharge the PW2 on a regular basis to keep those batteries healthy.

Umm, are you sure that will work?

Also not correct thing to do with Li Ion cells really! Keep them at 20c and cycle 30%-80% in an ideal world, nothing in the world is perfect tho.

Sheldon


Title: Re: Tesla Powerwall 2, one month in.....
Post by: brackwell on April 28, 2019, 08:58:04 AM
I know most people on here will be aware but certainly as we become more leccy efficient it has less to do with peak loads and more to do with the background draw.  My house draws some c200W 24/7 ie 4.8 kwh/day ie 1752kw/yrs. Thats 50% of my consumption and the national average!!  Peak draw is not that important because of the low time use. However one way would be to purchase lower peak draw items eg 2kw kettle instead of 3kw.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: pantsmachine on April 28, 2019, 11:07:23 AM
Brackwell, totally agree with you on background draw. We have chased our draw down to 144wh and would like to go lower. It seems so wrong to go to the trouble and expense of a battery install in whichever variant and then to leak away X amount in  nothing  very much at all.

My next check on return to Scotland will be the solar iboost unit. It according to swmbo kicks ks in and out now and then for a second or two at miniscule loads when sun is down. Will take a reading across a night to see if its 'real'check clamp position first and go from there. May just stick an inline timer set as off from 19.00 o 07.00 to ensure its not being a vampire.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Countrypaul on April 28, 2019, 03:20:58 PM
I know most people on here will be aware but certainly as we become more leccy efficient it has less to do with peak loads and more to do with the background draw.  My house draws some c200W 24/7 ie 4.8 kw/day ie 1752kw/day. Thats 50% of my consumption and the national average!!  Peak draw is not that important because of the low time use. However one way would be to purchase lower peak draw items eg 2kw kettle instead of 3kw.

Wow! 1752kw/day that must be some electricity bill you get ;D  I presume you mean 1752kWh /year (and also 4.8 kWh /day)


Title: Re: Tesla Powerwall 2, one month in.....
Post by: brackwell on April 28, 2019, 05:09:39 PM
Thanks -must have been still asleep.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: linesrg on April 29, 2019, 06:53:19 AM
Good Morning All,

I've been looking at my background load as well.

I've abandoned my trial with Vonage and a VOIP set-up here so have now unplugged their unit c/w pug I charger and the two separate mains driven handsets.

Now the Growatt is away I've unplugged the Shinebox router.

I'm 99% on the way to stopping my BT broadband contract and their router has now been switched off for the last 3 days (just running on the mobile broadband set-up).

The heating is still running though and it's a chilly 2oC here as I type this.

Regards

Richard


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on April 29, 2019, 11:36:47 AM
Congrats Fintray, and thanks for all your inputs.

If we're going to get competitive :), imported 14.6 kWh in the last 4 weeks, exported 3.1. However, there's the question of the birch tree. Since budding into leaf, it shades the array from sunrise and isn't totally unshaded until about noon, at the moment.

We need to reduce it by 50% to clear the panels, but left it in situ to see how we go. I reckon we'll be fine through summer, but autumn will be the deciding time.

All systems perfectly well behaved.

Drawing 200W with nothing much on.

Camping next weekend ...... :(


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on April 29, 2019, 12:17:26 PM
Hi Dickster

Not being competitive at all just to let people know how I get on, will be interesting once it has been in a year and especially over the winter period to see import.
14.6kWh would be about my normal import on most days sometimes less but often far more, so for 4 weeks it's great.


I also see the PW2 using small amounts of power, my import meter pulse reading usually sits at the same figure during the night until around 6am then it jumps up about 5 pulses. This is too early for the PV to be producing enough to charge so not sure if it is the PW2 readjusting as power starts to be produced.

I have to admit that I severely cut back the trees that were shading my panels, they're sycamores so they can recover and throw new shoots from the shortened trunk pretty well.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dan_b on April 29, 2019, 12:58:04 PM
I bought a 1kW kettle for exactly this reason as it can be run almost exclusively in my home on either the SolarPV generation, or the Powervault export.  It is frustratingly slow to bring to the boil though!

I know most people on here will be aware but certainly as we become more leccy efficient it has less to do with peak loads and more to do with the background draw.  My house draws some c200W 24/7 ie 4.8 kwh/day ie 1752kw/yrs. Thats 50% of my consumption and the national average!!  Peak draw is not that important because of the low time use. However one way would be to purchase lower peak draw items eg 2kw kettle instead of 3kw.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Tinbum on April 29, 2019, 02:17:07 PM
I bought a 1kW kettle for exactly this reason as it can be run almost exclusively in my home on either the SolarPV generation, or the Powervault export.  It is frustratingly slow to bring to the boil though!

I know most people on here will be aware but certainly as we become more leccy efficient it has less to do with peak loads and more to do with the background draw.  My house draws some c200W 24/7 ie 4.8 kwh/day ie 1752kw/yrs. Thats 50% of my consumption and the national average!!  Peak draw is not that important because of the low time use. However one way would be to purchase lower peak draw items eg 2kw kettle instead of 3kw.

I have my 600w kettle on a wirless switch so can turn it on before I want the water. I also have heaters on them controlled by an arduino. Last time we imported from the grid was early Feb. ;D


Title: Re: Tesla Powerwall 2, one month in.....
Post by: kristen on April 30, 2019, 03:10:31 PM
Haven't looked at my consumption lately ... I probably should ... but when we started thinking about it, some 9 years ago, I recorded the meter every week, started replacing incandescent bulbs, put some over-night timers on things, SHOUTED at the family if they left a light on (still do ... ) and we reduced our consumption by 50%. I kinda stopped trying beyond that, as muscle-memory was making sure that lights were turned off. We've gone from those "dim for first 5 minute" florescent bulbs to LEDs throughout the house in that time ... and any white goods etc. that die are replaced with A(MaxStars)

... but ...

... I now take the view that if I generate my own supply (and have a Battery to store from day-night and windy-to-calm), do I need to continue to be Eco, or can I justify running the house like a Christmas tree?

I am now thinking that Comfort is far more important than Economy, so long as it is Eco.

So is that bad? Aim to generate/store all I need, and then consume any amount / what I need within that?

For example, I am going to fit Heatpump for the UFH (which runs off biomass boiler thermal store in Winter) to cool it in summer.

I only run my outdoor lighting (about 30 bulbs, none of them more than 3W) from 8PM (annual average) to 11PM, but obviously I'm not looking at it the whole time ... but every time I get up to go to the kitchen / bed etc. I have the job of seeing the garden nicely lit up. Maybe I'll increase that so that it stays on until I go to bed ...


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on June 20, 2019, 02:30:03 PM
.....7 months in, here's some statistics for 5 months taken from Tesla app on phone.

Jan 1st to end of May. All kWh.

From grid 305

To grid 55

From sun 740

To house 914

from Powerwall 531

to Powerwall 647= 82% efficiency?

C*cked up charging a couple or 3 times, lazy errors.

Overall, pretty damn well pleased, as the system is working more or less exactly as I had hoped it would.

We now are using more electricity than before, as electric oven used instead of LPG, as and when we've got spare sunshine. Washing machine on on sunny days. Have yet to decide on butchery of birch tree to south east of panels.

Hope you find this interesting.










Title: Re: Tesla Powerwall 2, one month in.....
Post by: Fintray on June 20, 2019, 04:03:16 PM
Hi Dickster

Glad to hear you are pleased with the way your system is performing, I'm only coming up for 3 months with the Powerwall but like you I'm happy with it so far, only imported 2kWh in each of the last two months.
Be interesting to see the figures once they've done a full year and especially during the winter months.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: nowty on June 20, 2019, 08:29:54 PM

.....7 months in, here's some statistics for 5 months taken from Tesla app on phone.

from Powerwall 531

to Powerwall 647= 82% efficiency?



That's interesting, just checked my Sunny Island setup installed since March this year with second hand growatt lithium batteries.

Charged 1,544.6 kWh
Discharged 1,248.6 kWh

So that's 81% efficiency, so practically the same.

As a comparison, my old Sunny Island with Lead Acid batteries was much lower at 67%.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on June 21, 2019, 10:16:54 AM
That is interesting!

You mean to say my brand new shiny Tesla lithium ion batteries are not superior to your 2nd hand jobbies?!

Oh well, snobbery has it's price:)

Looking good for future home batteries made from old EVs .



Title: Re: Tesla Powerwall 2, one month in.....
Post by: pantsmachine on June 21, 2019, 11:18:05 AM
That is interesting!

You mean to say my brand new shiny Tesla lithium ion batteries are not superior to your 2nd hand jobbies?!

Oh well, snobbery has it's price:)

Looking good for future home batteries made from old EVs .

PMSL :) interested to read what the max load is available from each of these differing systems?


Title: Re: Tesla Powerwall 2, one month in.....
Post by: nowty on June 21, 2019, 03:17:16 PM
Looking good for future home batteries made from old EVs .

PMSL :) interested to read what the max load is available from each of these differing systems?

My Sunny Island is the 8kW version, but is limited to a constant 6kW load if the grid is available.

In either OffGrid mode, or if the grid fails (backup mode), it will go up to 8kW for 30 mins.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on June 24, 2019, 10:04:16 AM
I think the Powerwall2 is 3.7 kW max, but not sure.

We're so accustomed to being stingy that we rarely exceed, kettle + oven does pull from grid though.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: brackwell on June 24, 2019, 10:36:30 AM
.....7 months in, here's some statistics for 5 months taken from Tesla app on phone.

Jan 1st to end of May. All kWh.

From grid 305

To grid 55

From sun 740

To house 914

from Powerwall 531

to Powerwall 647= 82% efficiency?


Are you running a PV diverter for HW or EV ?

Very interesting thanks

Ken


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dan_b on June 24, 2019, 10:38:22 AM
That's why I bought a 1kW kettle so it doesn't pull from the grid even with my much lower power output capable PowerVault (1100W max discharge).


I think the Powerwall2 is 3.7 kW max, but not sure.

We're so accustomed to being stingy that we rarely exceed, kettle + oven does pull from grid though.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: dickster on June 24, 2019, 02:43:11 PM
Hi Brackwell,

No hot water tank. We evolved from mobile home with borrowed sub metered electric 300m from nearest power, so built new house with LPG boiler for shower, hot water in kettles for washing up, ablutions. Stove in winter, electric in summer. Didn't want solar thermal on roof. Luckily wangled new electric mains 3 years ago, but still follow same habits. In actual fact, I reckon the electric kettle is one of the most efficient ways to heat and use hot water in limited amounts.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: Tinbum on June 24, 2019, 03:51:54 PM
I reckon the electric kettle is one of the most efficient ways to heat and use hot water in limited amounts.

We have a 660w kettle on a wifi controlled socket so just turn it on a bit earlier or timed.


Title: Re: Tesla Powerwall 2, one month in.....
Post by: pantsmachine on June 24, 2019, 03:53:04 PM
All different eh?

On our Pylontech 2 battery stack we have a max 2.4kwh continuous discharge rate.
 
4 battery stack would raise to 4.8kwh continuous discharge rate.

I'll go up to four in a few years time if the first two start to show degradation. SWMBO is off to Alicante for a few days, I'll get my cheap n nasty 2kw kettle out for testing!

We use 1kwh from grid per day when its all working well, i'd like to lower that, kettle will be most of it i'm sure.