OT: Tesla Powerwall 2 update

[BrritSki]

Over the last month (April) we have used 2kWh of power from the grid.
Not per day – total, just for the very brief periods when our total
household load exceeds 5kW.
During that period the panels have generated 400 kWh and used 220 either
directly or to charge the battery. We have exported 180kWh which if we
were on Octopus Flux Export (it is still being setup) would have earned
us £28. When we go on to Flux, we will fully charge the batteries
overnight so everything generated during the day not needed to keep us
topped up can be exported (overnight import rate almost same as daytime
export, so no loss there) and then we will empty the battery during the
peak period 4-7PM earning us between £1.00 and £1.50 per day depending
on whether it is sunny or not in that 3 hour window. So about £60/mth
even in a cold wet April. It will be more for the next 4 months of peak
production and obviously less during Nov- Feb, but still not
insignificant and during that period there are opportunities for earning
even more during very high priced peak periods.

To say we are smugly pleased would be an understatement :)

Mike – have you ever heard of problems with PW2s and Broadband on the
forums you frequent ? Earlier this month our BT broadband was down for
2 weeks. I was complaining bitterly to BT about this obvs and had a call
with the executive customer support after an email to the CEO.
She was very helpful but not optimistic, so I decided to switch my Sky
connection to a hotspot (I had just bought another 20GB of mobile data
from GiffGaff) as we wanted to do some catchup and also see icons on
recorded progs. While I was doing this I had to power off the Sky box so
I thought I’d test whether it would turn off when PW switched to offgrid
mode (reader, it kept going). I then completed the change and rebooted.
A few minutes later I realised the broadband was back on.
This could have been due to 1 of 3 things:
1. The BT lady had finally given someone a rocket after I’d threatened
to cancel the contract due to lack of service and they’d remotely fixed
the disconnect in their system (the claimed cause but they b=never
seemed sure)
2. The Sky box change somehow affected the broadband
3. The Powerwall going off grid and then back on had somehow affected
the broadband

I think the first is unlikely as there was only about 15 minutes for all
that to happen. The second I think is unlikely. Third too maybe, but I
noticed another anomaly with broadband speed when I was doing something
with the PW, so I have my suspicions.

Of course it could just be coincidence, but given all this things
happened close together I have my doubts. EMNTK

[J. P. Gilliver]

In message <***@mid.individual.net> at Sun, 28 Apr 2024
12:43:10, BrritSki <***@gmail.com> writes
[]

Post by BrritSki
To say we are smugly pleased would be an understatement :)

[]
I realise it's a very difficult question, as it's difficult to capture
all the installation costs (such as any building work required, not just
the hardware), but have you got some _feeling_ - with say give or take a
third's latitude - what your payback period will be, in years? To the
point where you'll see a net gain from then on, assuming you are
anticipating such a point, rather than just a net _reduction_ in cost.

(I presume also it's too soon to get a feel for deterioration of parts -
instinct says the panels and maybe battery, but also the assorted
inverters, control systems, and so on.)

[BrritSki]

Post by J. P. Gilliver
[]

To say we are smugly pleased would be an understatement  :)

[]
I realise it's a very difficult question, as it's difficult to capture
all the installation costs (such as any building work required, not just
the hardware), but have you got some _feeling_ - with say give or take a
third's latitude - what your payback period will be, in years? To the
point where you'll see a net gain from then on, assuming you are
anticipating such a point, rather than just a net _reduction_ in cost.
(I presume also it's too soon to get a feel for deterioration of parts -
instinct says the panels and maybe battery, but also the assorted
inverters, control systems, and so on.)

Panels cost about £6k total 5 years ago and will be paid off from the
savings we make by the end of 2026. That included removal of a redundant
chimney stack by SoH (cost me a beer and a dinner) that would have cast
a shadow on panels and post installation of pigeon proofing to prevent
the flying rats nesting underneath (fitted by our window cleaner !)

Battery cost £8,000 total installed (now VAT free which was a serious
consideration) and current calculations are that we will save about £800
a year on top of our continuing FIT generation payments that are paying
off the panels, so a maximum 10 years to pay it off.

I fully expect that £800 to grow rapidly as electricity prices increase
and my estimates were all pessimistic e.g. not including the Octopus
Saving Sessions that make very high payments for occasional brief
periods when demand is at its highest. Mr McToodles makes a lot of money
on this afaik with his bigger system; assuming keeping 10% in battery
which may be unnecessary; and being conservative on solar generation
estimates - my simulation calculate 115kWh for April, when in fact it
was 180 this month, more than 50% more.

Of course we lose the interest on that capital, but that has only been
significant for the last couple of years and OTOH we have increased the
value of the house significantly (at least by the amount spent) and
improved our EPC rating.

We haven't seen any deterioration in our solar panel max. output, but we
have slightly more capacity installed than we can use. We regularly
flatline the output (i.e. reach the max) as we did as recently as the
16th April. If the panels have degraded it would just change the
duration of the flatline period, but I haven't noticed it yet. Panels
are not cleaned - seems to be enough rain to do that :/

Tesla guarantees the battery for 10 years. They do this by actually
having a larger capacity than is usable which means they don't need to
fill it to 100% which is what degrades batteries along with full
discharge, so I'll keep it at a 10% minimum. They also have very clever
battery charging and discharging software that also preserves the life
of the battery.

It will degrade, but it doesn't become unusable, just has less capacity.
Possibly 1% loss pa, which would still meet the guarantee and will be
enough to see me out.

[J. P. Gilliver]

In message <***@mid.individual.net> at Sun, 28 Apr 2024
14:43:16, BrritSki <***@gmail.com> writes
[]

Post by BrritSki
Panels cost about £6k total 5 years ago and will be paid off from the
savings we make by the end of 2026. That included removal of a
redundant chimney stack by SoH (cost me a beer and a dinner) that would
have cast a shadow on panels and post installation of pigeon proofing
to prevent the flying rats nesting underneath (fitted by our window
cleaner !)

So it looks like about a 7 year payback on the panels (though with handy
friends), and ...

Post by BrritSki
Battery cost £8,000 total installed (now VAT free which was a serious
consideration) and current calculations are that we will save about
£800 a year on top of our continuing FIT generation payments that are
paying off the panels, so a maximum 10 years to pay it off.

... 10 for the battery.
[]

Post by BrritSki
Of course we lose the interest on that capital, but that has only been
significant for the last couple of years and OTOH we have increased the

Indeed; looks like we're getting back to low inflation (and thus
interest rates) again. I'm glad it is settling down, even though I think
it's been good for the younger generation (don't I sound old!) to have a
_taste_ of what inflation is about. But things are so much easier
(especially for those with savings) when it's low.

Post by BrritSki
value of the house significantly (at least by the amount spent) and

Hadn't thought of that!

Post by BrritSki
improved our EPC rating.

And that will presumably increase the value too.

Post by BrritSki
We haven't seen any deterioration in our solar panel max. output, but
we have slightly more capacity installed than we can use. We regularly
flatline the output (i.e. reach the max) as we did as recently as the
16th April. If the panels have degraded it would just change the
duration of the flatline period, but I haven't noticed it yet. Panels
are not cleaned - seems to be enough rain to do that :/

By flatline, I presume you mean you reach some agreed maximum feed-in
level.

Post by BrritSki
Tesla guarantees the battery for 10 years. They do this by actually
having a larger capacity than is usable which means they don't need to
fill it to 100% which is what degrades batteries along with full
discharge, so I'll keep it at a 10% minimum. They also have very clever
battery charging and discharging software that also preserves the life
of the battery.
It will degrade, but it doesn't become unusable, just has less
capacity. Possibly 1% loss pa, which would still meet the guarantee and
will be enough to see me out.

And presumably the inverters mostly work or fail, rather than degrade.
(Ditto the control mechanisms.)

Thanks for the feedback! Definitely sounds worthwhile for house owners.
(Not sure about flat dwellers - I fear more likely to encounter planning
problems.)

[Mike McMillan]

Post by BrritSki
Over the last month (April) we have used 2kWh of power from the grid.
Not per day – total, just for the very brief periods when our total
household load exceeds 5kW.
During that period the panels have generated 400 kWh and used 220 either
directly or to charge the battery. We have exported 180kWh which if we
were on Octopus Flux Export (it is still being setup) would have earned
us £28. When we go on to Flux, we will fully charge the batteries
overnight so everything generated during the day not needed to keep us
topped up can be exported (overnight import rate almost same as daytime
export, so no loss there) and then we will empty the battery during the
peak period 4-7PM earning us between £1.00 and £1.50 per day depending
on whether it is sunny or not in that 3 hour window. So about £60/mth
even in a cold wet April. It will be more for the next 4 months of peak
production and obviously less during Nov- Feb, but still not
insignificant and during that period there are opportunities for earning
even more during very high priced peak periods.
To say we are smugly pleased would be an understatement :)
Mike – have you ever heard of problems with PW2s and Broadband on the
forums you frequent ? Earlier this month our BT broadband was down for
2 weeks. I was complaining bitterly to BT about this obvs and had a call
with the executive customer support after an email to the CEO.
She was very helpful but not optimistic, so I decided to switch my Sky
connection to a hotspot (I had just bought another 20GB of mobile data
from GiffGaff) as we wanted to do some catchup and also see icons on
recorded progs. While I was doing this I had to power off the Sky box so
I thought I’d test whether it would turn off when PW switched to offgrid
mode (reader, it kept going). I then completed the change and rebooted.
A few minutes later I realised the broadband was back on.
1. The BT lady had finally given someone a rocket after I’d threatened
to cancel the contract due to lack of service and they’d remotely fixed
the disconnect in their system (the claimed cause but they b=never
seemed sure)
2. The Sky box change somehow affected the broadband
3. The Powerwall going off grid and then back on had somehow affected
the broadband
I think the first is unlikely as there was only about 15 minutes for all
that to happen. The second I think is unlikely. Third too maybe, but I
noticed another anomaly with broadband speed when I was doing something
with the PW, so I have my suspicions.
Of course it could just be coincidence, but given all this things
happened close together I have my doubts. EMNTK

No, nuffink, not no how, we had a day when the grid went off 10 or 11 times
within an hour or two but we were totally unaware of it happening - and our
NAS and our broadband carried on as normal after the event. We probably
wouldn’t have noticed all the 2 second outages on the broadband i suppose.

[Mike McMillan]

Post by Mike McMillan

Post by BrritSki
Over the last month (April) we have used 2kWh of power from the grid.
Not per day – total, just for the very brief periods when our total
household load exceeds 5kW.
During that period the panels have generated 400 kWh and used 220 either
directly or to charge the battery. We have exported 180kWh which if we
were on Octopus Flux Export (it is still being setup) would have earned
us £28. When we go on to Flux, we will fully charge the batteries
overnight so everything generated during the day not needed to keep us
topped up can be exported (overnight import rate almost same as daytime
export, so no loss there) and then we will empty the battery during the
peak period 4-7PM earning us between £1.00 and £1.50 per day depending
on whether it is sunny or not in that 3 hour window. So about £60/mth
even in a cold wet April. It will be more for the next 4 months of peak
production and obviously less during Nov- Feb, but still not
insignificant and during that period there are opportunities for earning
even more during very high priced peak periods.
To say we are smugly pleased would be an understatement :)
Mike – have you ever heard of problems with PW2s and Broadband on the
forums you frequent ? Earlier this month our BT broadband was down for
2 weeks. I was complaining bitterly to BT about this obvs and had a call
with the executive customer support after an email to the CEO.
She was very helpful but not optimistic, so I decided to switch my Sky
connection to a hotspot (I had just bought another 20GB of mobile data
from GiffGaff) as we wanted to do some catchup and also see icons on
recorded progs. While I was doing this I had to power off the Sky box so
I thought I’d test whether it would turn off when PW switched to offgrid
mode (reader, it kept going). I then completed the change and rebooted.
A few minutes later I realised the broadband was back on.
1. The BT lady had finally given someone a rocket after I’d threatened
to cancel the contract due to lack of service and they’d remotely fixed
the disconnect in their system (the claimed cause but they b=never
seemed sure)
2. The Sky box change somehow affected the broadband
3. The Powerwall going off grid and then back on had somehow affected
the broadband
I think the first is unlikely as there was only about 15 minutes for all
that to happen. The second I think is unlikely. Third too maybe, but I
noticed another anomaly with broadband speed when I was doing something
with the PW, so I have my suspicions.
Of course it could just be coincidence, but given all this things
happened close together I have my doubts. EMNTK

No, nuffink, not no how, we had a day when the grid went off 10 or 11 times
within an hour or two but we were totally unaware of it happening - and our
NAS and our broadband carried on as normal after the event. We probably
wouldn’t have noticed all the 2 second outages on the broadband i suppose.

Some days, we charge the battery to full capacity during the lowest cost
(and cleanest!) 30 minute slots and later, during the peak demand time,
send 10-20 kWh back to the grid. We might be buying in at 0 -8 pence per
kWh but selling back at 15 pence per kWh. We do it of course in an attempt
to help the grid out during its’ times of greatest needs of course😉

[Mike McMillan]

Post by Mike McMillan

Post by Mike McMillan

Post by BrritSki
Over the last month (April) we have used 2kWh of power from the grid.
Not per day – total, just for the very brief periods when our total
household load exceeds 5kW.
During that period the panels have generated 400 kWh and used 220 either
directly or to charge the battery. We have exported 180kWh which if we
were on Octopus Flux Export (it is still being setup) would have earned
us £28. When we go on to Flux, we will fully charge the batteries
overnight so everything generated during the day not needed to keep us
topped up can be exported (overnight import rate almost same as daytime
export, so no loss there) and then we will empty the battery during the
peak period 4-7PM earning us between £1.00 and £1.50 per day depending
on whether it is sunny or not in that 3 hour window. So about £60/mth
even in a cold wet April. It will be more for the next 4 months of peak
production and obviously less during Nov- Feb, but still not
insignificant and during that period there are opportunities for earning
even more during very high priced peak periods.
To say we are smugly pleased would be an understatement :)
Mike – have you ever heard of problems with PW2s and Broadband on the
forums you frequent ? Earlier this month our BT broadband was down for
2 weeks. I was complaining bitterly to BT about this obvs and had a call
with the executive customer support after an email to the CEO.
She was very helpful but not optimistic, so I decided to switch my Sky
connection to a hotspot (I had just bought another 20GB of mobile data
from GiffGaff) as we wanted to do some catchup and also see icons on
recorded progs. While I was doing this I had to power off the Sky box so
I thought I’d test whether it would turn off when PW switched to offgrid
mode (reader, it kept going). I then completed the change and rebooted.
A few minutes later I realised the broadband was back on.
1. The BT lady had finally given someone a rocket after I’d threatened
to cancel the contract due to lack of service and they’d remotely fixed
the disconnect in their system (the claimed cause but they b=never
seemed sure)
2. The Sky box change somehow affected the broadband
3. The Powerwall going off grid and then back on had somehow affected
the broadband
I think the first is unlikely as there was only about 15 minutes for all
that to happen. The second I think is unlikely. Third too maybe, but I
noticed another anomaly with broadband speed when I was doing something
with the PW, so I have my suspicions.
Of course it could just be coincidence, but given all this things
happened close together I have my doubts. EMNTK

No, nuffink, not no how, we had a day when the grid went off 10 or 11 times
within an hour or two but we were totally unaware of it happening - and our
NAS and our broadband carried on as normal after the event. We probably
wouldn’t have noticed all the 2 second outages on the broadband i suppose.

Some days, we charge the battery to full capacity during the lowest cost
(and cleanest!) 30 minute slots and later, during the peak demand time,
send 10-20 kWh back to the grid. We might be buying in at 0 -8 pence per
kWh but selling back at 15 pence per kWh. We do it of course in an attempt
to help the grid out during its’ times of greatest needs of course😉

Just for clarity, the tariff we are on is Octopus Energy Agile; as the name
suggests, there are variations in price throughout the day and night. On a
typical day, the rate might be up to 30 pence or more per kWh but we don’t
draw from the grid at such times. Tonight and tomorrow afternoon, the rate
will vary between approx. 14 pence and 5 pence. When there is a lot of
solar power and wind available, the rate can even go negative when they pay
us to take energy off their hands - naturally, I like to help them out with
their embarrassing surplus ….

[BrritSki]

Post by Mike McMillan
Just for clarity, the tariff we are on is Octopus Energy Agile; as the name
suggests, there are variations in price throughout the day and night. On a
typical day, the rate might be up to 30 pence or more per kWh but we don’t
draw from the grid at such times. Tonight and tomorrow afternoon, the rate
will vary between approx. 14 pence and 5 pence. When there is a lot of
solar power and wind available, the rate can even go negative when they pay
us to take energy off their hands - naturally, I like to help them out with
their embarrassing surplus ….

Yep. With my "Full by 4" strategy it is unlikely that we'd have much
spare capacity to take advantage of negative import rates.

I'd rather have the certainty of a decent income every day than gamble
on getting more, even if the gamble most often pays off if you're paying
attention.

[BrritSki]

Post by Mike McMillan
Some days, we charge the battery to full capacity during the lowest cost
(and cleanest!) 30 minute slots and later, during the peak demand time,
send 10-20 kWh back to the grid. We might be buying in at 0 -8 pence per
kWh but selling back at 15 pence per kWh. We do it of course in an attempt
to help the grid out during its’ times of greatest needs of course😉

Of course !

You need to be on Agile to do that though I think and pay close
attention to prices and I doubt if I CBA to do the latter frequently
enough to make the switch worthwhile.