PITA
Model 3 Performance
Not completely on 3 phase. Our house is still on Single Phase.
Just the two car chargers on 3 Phase at the moment.
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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
Not completely on 3 phase. Our house is still on Single Phase.
Just the two car chargers on 3 Phase at the moment.
WannabeOwner
Well-Known Member
As far as DNO is concerned haven't you got 3-Phase? Just you've chosen to configure the house to only use one phase (very convenient for power-backup, not so good for "Balanced use across all 3-Phases" which I thought they were quite keen on - maybe only once a connection is big enough to draw GWs of power?!)
We have 3-phase at work (its just a small office building). One of the phases was dickie for quite some time. Every third office (and house in the street!) went off in sympathy whenever that happened. Must piss of consumers who actually had e.g. 3-phase motors.
Out of interest, if you have two PW do they charge at 10kw combined overnight from grid? I haven’t been able to find out anywhere. I only have one but thinking for the future.
PITA
Model 3 Performance
Our setup is very convenient actually and works really well.
All house supply is on Single Phase and backed up by two Powerwalls...
I'm going to move our Heat Pump onto L2 as we still have a Gas Central Heating system on L1 (on backup).
A new kitchen extension will have big appliances on L2 & L3 (cookers, induction hobs) etc not on backup... but Washing / drying / microwave will be on L1 backup.
Then hopefully it'll balance nicely, and 3 car chargers primary feed staggered over L1, L2 & L3
I'm almost there now. Just two things left
1) 100A per phase upgrade
2) Additional 4 kWp Solar Array
I set the export tariff at 30p during peak time and it did seem to stop the PW charging when there was a glimmer of sun this morning. I have myenergi eddi and Zappi so it diverted to them, but I can easily schedule them to go into stop mode during the Flux peak period.
PITA
Model 3 Performance
Yes but only if the DNO allows it.
Ours have 4 Hours to charge 27.5 kWh storage. So typically charge at around 7kW over 4 hours. But if I start charging late, they'll go straight to 10kW
Tesla set the charge limit based on your G99 Application and DNO acceptance. I've had it once where my charge limit dropped to 3.4 kW ... quick call to Tesla and they reset it back to 10 kW. Must be a settings glitch now and then.
Great thanks. You wouldn’t have the Tesla number handy so I can call re something else would you?
PITA
Model 3 Performance
What I used was....
[email protected]
Burgemeester Stramanweg 122, 1101 EN Amsterdam, Netherlands,
p. +44 1628 450630 UK
Here's the screenshot of the Powerwall Installation limit control panel set by your installer...
PITA
Model 3 Performance
... but if your network cabling is restricted in some way, you might be capped at 3.5 kW import regardless of how many Powerwalls you have.
ACarneiro
Active Member
You have a site import limit of 5kW? Surely that can’t be right.
Your whole home supply can’t cope with a demand greater than 21A??
PITA
Model 3 Performance
The screenshot is the Powerwall Installation site limit control panel set by your installer... not my home Limit.
So in the screenshot, the Powerwall site import limit is set at 5 kW total. So no matter how many Powerwalls you have, if it's set at 5 kW... that's how much they will charge at in total.
We have two Powerwalls, and I know our Powerwall site charges at up to 10 kW... and then there is the rest...
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ACarneiro
Active Member
That’s not how Site Import Limit works, in my experience.
When Tesla erroneously set mine to 10kW, I was NEVER drawing more than 10kW from the grid. Even to the point where, when I was using 13kW with car charging, heat pumps and water heating, 10kW was coming from the grid and 3kW was coming from the Powerwalls.
I changed it to 22kW now and it does was it says on the tin: the Powerwalls will modulate their charge rate so that the total import from the grid never exceeds 22kW (which is about 95A at a nominal 230V. I left 5A spare just in case).
PITA
Model 3 Performance
Well, I can tell you my explanation is accurate to the actual Tesla Associate Technical Support Engineer EMEA... told me... and in my experience of running our system setup.
So, what's going on in your case I have no idea...
ACarneiro
Active Member
Well, we’re either both right or both wrong.
But as the system is working as intended for both of us….. who cares?
PITA
Model 3 Performance
Well, we’re either both right or both wrong.
But as the system is working as intended for both of us….. who cares?
Indeed... we could both be right actually.
Just different settings could be making the difference.
With our Powerwalls and Ev Chargers, they may fluctuate depending on loading and time remaining. Even the Grid loading might influence it all...
Pete UK
Member
Hi all,
Hope you’re all doing good. I recognise some of you from the Model Y Delivery thread. Long post coming up….
Spent the last week reading this whole thread !
Thanks to all who have been kind enough to share some very very helpful info.
I’ve had the Model Y for a complete year now. So I’ve got good usage data on that. (14,000 (normal type of remote defrosting and sentry/ dog mode) miles a year = 4,500kW. Hope that’s useful to someone.
We are getting a solar PV and battery system sorted. Possibly looking at an air-rad heat pump in a year or two (at the mo using gas rads and electric water cylinder which seems to be on all the time and pumping hot water around a loop in the house
). Had 2 quotes in so far but I didn’t really like the system set ups and the installers didn’t seem all that knowledgeable about battery storage, how to design a system to best make use of energy plan time of use or had much flexibly with panels or batteries or power-cut back up etc. it was just a case of “ok we’ll add some more and this is the battery. oh ok, we’ll add one more then, oh ok add 2 more then!) Roof plan and panel numbers was easy; Just put as many as possible up there, despite the orientation !
I am a relatively high user (that doesn’t sound at all that good reading it back
)
Was thinking of going down the powerwall and TEP route until they closed it last week)
To me that would have worked and saved about an extra £1,000 a year just by having access to the plan plus the Solar savings of £2,500 a year on 7,000kW generated instead of buying at current SSE rate of 0.35p.
South side of the roof is 3 stories up (The front, not much space). North side (obviously perfect for panels but facing the wrong way!) east side not ideal due to stepping down half way and some shading at certain times of the year. No West roof. It’s a Victorian semi.
Quote 1;
9.96kW panel system. (Estimated generating 7,000kW pa)
24x 415W panels; 5 south, 8 north, 11 east.
6kw Solis hybrid inverter with pure storage 2 5kW DC battery attached to it- N&S strings.
3kW inverter (not connected to battery!) - E 2 strings.
Optimisers on 9 of the panels !
Total cost: £16,100 (incl 5% discount)
£12,500 equipment, £3,500 electrical and roof work, scaffolding £1,000
Quote 2;
11.45kW system (Estimated generating 7,000kW pa)
27x 425 Panels; 5 South, 8 North, 14 East
10kW (2x5) Power mate P5 inverters
27 Tigo optimisers
15.3 kW batteries (3x power mate P5.1)
Total cost: £21,300
Quote 3; TBA
The installer that I am waiting for the quote on, I think is the best qualified and knowledgeable. Also very busy. But also has a very good reputation. They use all the Solar edge inverters and SE DC batteries as well as being an authorised Tesla Powerwall installer. I haven’t got the quote back from them yet as they are still designing the system. The design I think will be very optimal. For example 1) it’s DC so unlike the powerwall it doesn’t go DC—>AC—>DC—>AC again. Just DC—>AC. Losing maybe 3% instead of 9%. So that’s a 6% gain just there! 2) You can send the peak “clipped” load direct to the battery instead of it going through the inverter! So you’d capture that valuable % extra as well. The proposed 10kW Solar Edge battery you can schedule it to charge off peak (or not, or some) using different profiles (as many as you want) one for each quarter, month, week or day if you want !). That gives it a set and forget advantage that you can’t do with the Powerwall. To maximise off-peak usage without faffing about every day with forecasts. I like that idea.
But then I like to Powerwall as well, as it fits with the car and charger and has ONE clean interface. But if I’m having to faff with 3 other interfaces all the time then that’s not as good.
Useage; 19,000 total pa (probably 30 kW a day in summer? 50 in winter? Excluding the car)
House 14,500 (planning IO)
Car 4,500
(Solar -7,000 hopefully)
I’m pretty sure our largest usage is;
1) 7.4kW rated electric underfloor heating mats in a 30+ Sq m kitchen with no other heating source. (Planning to add 2 radiators instead). Plus 4 other small underfloor mats in bathrooms and a garage sized garden studio.
2) The hot water cylinder water that’s pumped around in a loop and heated almost 24/7.
I’m thinking I need the max panel version due to non optimal roof and probably 30kW of SE storage. I don’t mind paying for it if it works, it’s reliable and I don’t have to faff about with it every night. Although I do like a bit of faffing and tweaking
I’m happy to charge the car at 10p for up to 6 hours on IO. That’s 25% to 80% car battery top up, so thats as close to the max I’d do anyway. More like 60-80% most days.
Any car charging from excess in the summer will be a bonus. Worst case £450 a year at 10p is ok. £37.50pm to run the car is a bargain!
Getting some good feedback on the Powerwall pro’s and cons here but…
My question is this;
What do you think?
Has anyone got a full Solar Edge PV inverter system with SE battery, SE smart water system? Grid- down backup? Is it any good? Is it worth the expected extra outlay? Will it play nicely with the Tesla Gen 3 wall connector/ Model Y?
Thanks again for all the hard work and tips. Guess I’m looking for confirmation on what I’m thinking already. Which is now erring towards an integrated Solar edge system when it was Tesla before. I know I can’t off set it all but want gain the most savings. If I can save £3,500 a year it seems worth the investment. That’s a good rate of return.
Cheers !
Hope you’re all doing good. I recognise some of you from the Model Y Delivery thread. Long post coming up….
Spent the last week reading this whole thread !
Thanks to all who have been kind enough to share some very very helpful info.
I’ve had the Model Y for a complete year now. So I’ve got good usage data on that. (14,000 (normal type of remote defrosting and sentry/ dog mode) miles a year = 4,500kW. Hope that’s useful to someone.
We are getting a solar PV and battery system sorted. Possibly looking at an air-rad heat pump in a year or two (at the mo using gas rads and electric water cylinder which seems to be on all the time and pumping hot water around a loop in the house
). Had 2 quotes in so far but I didn’t really like the system set ups and the installers didn’t seem all that knowledgeable about battery storage, how to design a system to best make use of energy plan time of use or had much flexibly with panels or batteries or power-cut back up etc. it was just a case of “ok we’ll add some more and this is the battery. oh ok, we’ll add one more then, oh ok add 2 more then!) Roof plan and panel numbers was easy; Just put as many as possible up there, despite the orientation !I am a relatively high user (that doesn’t sound at all that good reading it back
)Was thinking of going down the powerwall and TEP route until they closed it last week)
To me that would have worked and saved about an extra £1,000 a year just by having access to the plan plus the Solar savings of £2,500 a year on 7,000kW generated instead of buying at current SSE rate of 0.35p.South side of the roof is 3 stories up (The front, not much space). North side (obviously perfect for panels but facing the wrong way!) east side not ideal due to stepping down half way and some shading at certain times of the year. No West roof. It’s a Victorian semi.
Quote 1;
9.96kW panel system. (Estimated generating 7,000kW pa)
24x 415W panels; 5 south, 8 north, 11 east.
6kw Solis hybrid inverter with pure storage 2 5kW DC battery attached to it- N&S strings.
3kW inverter (not connected to battery!) - E 2 strings.
Optimisers on 9 of the panels !
Total cost: £16,100 (incl 5% discount)
£12,500 equipment, £3,500 electrical and roof work, scaffolding £1,000
Quote 2;
11.45kW system (Estimated generating 7,000kW pa)
27x 425 Panels; 5 South, 8 North, 14 East
10kW (2x5) Power mate P5 inverters
27 Tigo optimisers
15.3 kW batteries (3x power mate P5.1)
Total cost: £21,300
Quote 3; TBA
The installer that I am waiting for the quote on, I think is the best qualified and knowledgeable. Also very busy. But also has a very good reputation. They use all the Solar edge inverters and SE DC batteries as well as being an authorised Tesla Powerwall installer. I haven’t got the quote back from them yet as they are still designing the system. The design I think will be very optimal. For example 1) it’s DC so unlike the powerwall it doesn’t go DC—>AC—>DC—>AC again. Just DC—>AC. Losing maybe 3% instead of 9%. So that’s a 6% gain just there! 2) You can send the peak “clipped” load direct to the battery instead of it going through the inverter! So you’d capture that valuable % extra as well. The proposed 10kW Solar Edge battery you can schedule it to charge off peak (or not, or some) using different profiles (as many as you want) one for each quarter, month, week or day if you want !). That gives it a set and forget advantage that you can’t do with the Powerwall. To maximise off-peak usage without faffing about every day with forecasts. I like that idea.
But then I like to Powerwall as well, as it fits with the car and charger and has ONE clean interface. But if I’m having to faff with 3 other interfaces all the time then that’s not as good.
Useage; 19,000 total pa (probably 30 kW a day in summer? 50 in winter? Excluding the car)
House 14,500 (planning IO)
Car 4,500
(Solar -7,000 hopefully)
I’m pretty sure our largest usage is;
1) 7.4kW rated electric underfloor heating mats in a 30+ Sq m kitchen with no other heating source. (Planning to add 2 radiators instead). Plus 4 other small underfloor mats in bathrooms and a garage sized garden studio.
2) The hot water cylinder water that’s pumped around in a loop and heated almost 24/7.
I’m thinking I need the max panel version due to non optimal roof and probably 30kW of SE storage. I don’t mind paying for it if it works, it’s reliable and I don’t have to faff about with it every night. Although I do like a bit of faffing and tweaking
I’m happy to charge the car at 10p for up to 6 hours on IO. That’s 25% to 80% car battery top up, so thats as close to the max I’d do anyway. More like 60-80% most days.
Any car charging from excess in the summer will be a bonus. Worst case £450 a year at 10p is ok. £37.50pm to run the car is a bargain!
Getting some good feedback on the Powerwall pro’s and cons here but…
My question is this;
What do you think?
Has anyone got a full Solar Edge PV inverter system with SE battery, SE smart water system? Grid- down backup? Is it any good? Is it worth the expected extra outlay? Will it play nicely with the Tesla Gen 3 wall connector/ Model Y?
Thanks again for all the hard work and tips. Guess I’m looking for confirmation on what I’m thinking already. Which is now erring towards an integrated Solar edge system when it was Tesla before. I know I can’t off set it all but want gain the most savings. If I can save £3,500 a year it seems worth the investment. That’s a good rate of return.
Cheers !
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I was one of the few on the TEP and will regret its passing.
The advantages are
1. It is set and forget. You do not have to alter timing of cooking, washing, charging of the EVs as ever unit at every time costs the same. That is the most useful advantage.
2. I have a 8.96 array which generated 7.9MWh in year 2022. There is no way you can plan to hold that amount on site so the important thing for me is to export at a top rate during those periods. Although we have 2 EVs, we are retired and jointly only do 10-12000 miles pa.
3. When it was at the 8p rate it was considerably cheaper than GO which I had previously been on. Now at 25p it is less frugal.
I aim to keep the net export as high as possible throughout the year as that becomes the only figure that matters. In both 2021 and 2022 that figure was between 5 and 5.4MWh. My total consumption is 12 -13 MWh pa.
Although I am sure I will be able to game the system FLUX will require much more effort.
The advantages are
1. It is set and forget. You do not have to alter timing of cooking, washing, charging of the EVs as ever unit at every time costs the same. That is the most useful advantage.
2. I have a 8.96 array which generated 7.9MWh in year 2022. There is no way you can plan to hold that amount on site so the important thing for me is to export at a top rate during those periods. Although we have 2 EVs, we are retired and jointly only do 10-12000 miles pa.
3. When it was at the 8p rate it was considerably cheaper than GO which I had previously been on. Now at 25p it is less frugal.
I aim to keep the net export as high as possible throughout the year as that becomes the only figure that matters. In both 2021 and 2022 that figure was between 5 and 5.4MWh. My total consumption is 12 -13 MWh pa.
Although I am sure I will be able to game the system FLUX will require much more effort.
WannabeOwner
Well-Known Member
Hero! 103 pages / 7 days = 97 minutes per page. Comprehension should be good
Winter heating? You will get diddly-squat from PV in winter (Dec/Jan will be 10% of mid Summer peak). Oct-mid-Nov and Mid-Feb onwards you will get some - but weather has to co-operate by being sunny on cold [central heating] days ...
I suggest you need useful logged data for consumption. You need to know hour-by-hour what you use in various scenarios:
(Hour-by-hour because you need to know what is during Off Peak (you can price that buying from Grid), whether likely to have some PV at that time, and for the rest "Price from grid")
Winter, artic outside, heating on full blast. Both "house occupied" and "away for weekend"
Normal average Summer day consumption. Maybe a party-day as well as an ordinary at home day - and a weekday / weekend day. Baking / Washing / tumble drying days (if you have those high-consumption days) vs. normal days
Smart Meter (got one of those?) might give you that data, or a plug in gadget such as Owl
Then, if you are up for it, you need to crunch those numbers. I think the calcs you need are for:
Winter days - assuming you will charge the battery 100% on Off Peak (in Spring/Autumn that will be partially-charged on some/majority of nights - depending on prediction of tomorrow's sun [Tesla and Givenergy will do that, or you can roll-your-own using e.g. Solcast])
What is the consumption from end-of-off-peak to start-of-off-peak following night? Your ideal would be a battery that can cover that. I guess 80:20 would do - so what size battery would cover 80% of the days usage.
However, you probably don't actually want to try to achieve that in Dec/Jan. By mid Feb you will get some useful sun PV (when it isn't raining - if it rains then same sum-game as Dec/Jan). Use figures for likely Monthly generation which you can put in the mix. My battery does about 1/3rd of a winters daily Peak tariff, but by mid Feb I have days where I use zero Peak tariff, and only charge battery to 50% on Off Peak - enough to run until Sun Up, and then Sun will charge to 100%-ish, and then that will run down from 14:00 - 15:00 (Feb PV-SunDown) onwards ... up until Off Peak starts.
In Summer the tables turn. You want the battery to go from "PV SunDown" (the moment at which the PV is generating less than the house is using) until PV-SunUp. If you have East and West arrays that will probably be 2 hours better than a South-only array. Of course that includes the night time, which will be your lowest consumption, which helps eek the battery out. My battery will last me a bit over 12 hours (over night) at Summer Consumption, at which time my PV-SunDown to SunUp is about 7PM to 7AM.
On top of that no point installing panels if you cannot use their output - bigger battery, or a car (parked at home during nice sunny summer days, Natch!), or a summer usage - Air Con, Hot Tub, Immersions etc.
Yeah, me too
Not sure the North are going to contribute enough (on top of the others) to make them worthwhile.
Multiple elevations may require multiple inverters, or some other fancy "balancing" stuff. (Not something I know about, but might mean that North benefit is offset by having to buy "more stuff" like inverters, wiring, scaffolding, etc.)
Ask them what their lead-time is. If it is 12 months (might well be ...) then you might want something else
If you are going to plug-and-forget that won't matter, You could install e.g. a Zappi charger and let it just divert excess PV to Car (if it is at home and plugged in) and use Eddie (IIRC??) to divert excess power to Immersion and so on.
If you want to tinker then I think it it definitely helps. I can go into Tesla APP, see that the battery is almost full, PV has several hours peak to go, and I can start one/both cars charging (and choose low AMPs if I only want to divert a bit). I don't think I'd do that as often if I had to go in and out of several APPs. All that can be "automated" with Tesla API. Again, harder if there are several different APIs to make connections to - and X-times more hassle whenever anything changes in any/one of them.
I don't think that figure is useful. You need a) household consumption in various scenarios (as described above) and then match that with likely PV production (month by month). I suggest you have a go with PVWatts - that will let you figure out (for your exact location) what roof area you have (for each elevation) and [at that Lat/Long] what your likely generation will be month-by-month
Make separate calcs, for each of your orientations. Then copy/paste the month-by-month production figures to a spreadsheet - and then see when producing more than house will use, and when not enough. That can influence battery size (or whether you need car to be at home any day in Summer when sun is shining! or also buy an Air Con system for the house! and also clarify that you aren't going to get any benefit for winter heating in Dec / Jan at least)
I have a loop system like that. We have a pump (special hot water pump - I think that is referred to as "bronze") which comes on to pump the ciruit, on a 5 minute timer and overridden if thermostat sees that the return temperature is "hot"). We have bedside / bathroom switches (on home automation system) to "trigger" that. The plumbing is configured so that there is a non-return valve when pump is running, and when not the hot water can flow both ways round the loop - which provides benefit of more hot water "flow" than only a single circuit.
Before we put the pump in the water cylinder was cold within about 4 hours.
We also have towel radiators on the hot water circuit (special towel rails, stainless maybe?, sorry about that ...). Run the pump (and/or run a bath/shower) and the flow of hot water heats the towel rail, which coincides with use of course. Or just turn the pump on if you want the towels heated at any other time.
If you are doing it you want to put up as many panels as you will ever need - there is a fixed cost for scaffolding and "getting installer on site", and quite possibly "one inverter", so incremental cost of a few more panels is small.
If you are sizing to have a reasonably decent amount in Spring / Autumn you will definitely have excess in Summer.
Adding Air Con, in Summer, would use up some excess ... even a plug in one with a snorkel-pipe out-the-window would do. Or some other heavy summer time usage.
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WannabeOwner
Well-Known Member
A 10kw SolarEdge system would be better if putting optimisers on that many panels. However it looks like Octopus will not pay well for PV exports if your total PV inverters are over 9kw. Hence I would be thinking 8kw SolarEdge for the 27x 425 as they will never generate near their claimed rating on your roof.
I think SolarEdge batteries are overpriced and for my home are thinking of having the battery system separate from the PV inverters but don't yet know if Octopus Flux permits it.
