This video revisits a previous Tesla Powerwall 2 video I uploaded in December 2020 where I
made an error in my payback calculations. Plus I'll cover a few additional points
that I didn't mention in that previous video. And also I'll give you a big picture view of our
total costs and savings over the past 10 years with solar, 3 1/2 years of our Tesla Powerwall
and just shy of 3 years with our EV ownership. So stay tuned.
Hi John here. In the previous video I uploaded in December 2020 a 2 year review of the Powerwall
I made an error in my maths. Normally I'd not worry too much about that as typically
only a few people would see it. However, for some reason the original video has
gone viral in the past few weeks. Well viral for my channel anyway. And as I record this
that original video has had 185,000 views and now is my most viewed video on the channel! I'm sure
memes will soon start to circulate to commemorate this momentous occasion. What was the correction?
Firstly, when I was working out the costings I multiplied the then 2 years of ownership by 48
rather than 24 months. As a result this reduced my savings by half. Thank you to all of you who
pointed that out. As it became so popular more and more people pointed this mistake out so I thought
I'd address it in this video. I will revisit the cost savings as we now have 3 years of data and
it's a much rosier picture. Hey I'm already 50% up due to my maths error! Secondly, a few of you
pointed out that I had not included any savings from using the Powerwall to charge EVs rather
than spending money buying fuel for an internal combustion engine car. Good point. So that's now
included along with solar savings for charging the cars. Thirdly, some people commented that
I did not include the cost of the solar pv in my calculation in that video. And I wanted to explain
my reasoning for not including it. Our 4kW array installed in September 2011 has a Feed in Tariff.
We get quarterly payments from our energy company for every kWh of solar power we generate. 50% of
that generation total is also taken as Deemed Export. And we get a payment for that too
incorporated into our overall FiT payments. Over the past 10 years our average annual fit
feed in tariff payment, or FiT payment for short, has been £2,239.23p.
To date we've received a total of £22, 81.76p in FiT payments. This means our 2011 4kW solar
installation costs were covered in December 2018 just from FiT payments. This break even point
was at the same time we had the Powerwall installed and this is the reason I didn't
include the costs of the solar PV in my initial video. I should have explained that at the time.
Obviously if I had included the solar costs I'd be costing it twice and we don't want to
go down that doubling up costings route again do we! Oh and the FiT payments don't take into
account savings we made from reducing our electricity bills by having solar panels,
but more on that later. At this point it's a good time to tell you about all the components
and costs in our total system to date. That's everything we had bolted onto the house and that
gives you a good starting point. Our 4kW array with a 3.8 inverter installed in September 2011
cost £15,225.00. The Tesla Powerwall 2 and the myenergi zappi installed in December 2018
cost £7,141.66p. Myenergi eddi, harvi, and comms hub installed in July 2019 cost £445.83p.
Our 2.34kW array with a 2.2 inverter installed in October 2019 was £5,795.00.
That is a total of £28,607.49p. Our overall total FiT payments to date at the time of recording
this video in April 2022 are £22,681.76p. Which leaves us in deficit by £5,925.73p.
Based on our annual average FiT payments we will break even in 2.6 years just from our FiT payments
alone. And again this doesn't factor in any other savings we made along the way. Our plan has always
been that the FiT payments we receive are ploughed back into improving the efficiency of our house.
We want to reduce our reliance on gas and electricity from the grid and one of the best ways
to achieve this is to reduce our heat loss by insulating and reducing drafts.
The cheapest energy is the energy you don't use. And that's what we've been doing and
it's very much work in progress. If you've not seen any of those videos that we've done
so far I'll put a link to the video up in the top corner here also in the description
down below. Overall savings let's have a look at that. I'll start off with the Powerwall 2
data and how much we've saved over 3 years of ownership here in the UK with the Powerwall 2.
Then we'll look at the savings we've generated from our solar panels, our eddi which heats our
hot water and the zappi which charges our EVs either from solar or at cheap off-peak
rates. The Tesla Powerwall was installed and commissioned on the 4th of December 2018. It has
had only 3 days offline in its lifetime those 3 consecutive days were just after the installation.
And it was fixed remotely by Tesla. Since then it's been working without any glitches and the
cutoff point for this data when I collected it was the 4th April 2022. Which is 1,217 days, 3 years
and 3 months. Now when you have a home storage battery there are a number of ways it can be used.
I'm calculating the costs based on how we use it. Other people on different energy tariffs
will have different outcomes. So for example if you're on the the TEP plan, the Tesla Energy Plan
with Octopus Energy then the savings and outcome will be completely different compared to mine.
If you are on the Octopus Agile tariff and take advantage of Agile Export rates then again your
outcomes will be different from mine. And I guess it's important to make this distinction comparing
apples with apples. If you are looking at other people's costs and savings with their home storage
battery and or solar. And I'm not inferring them my way the right way and theirs is wrong you know,
far from it. How someone uses their energy whilst maintaining their savings and reducing their costs
will be different from household to household. In the last video I use the amortised costs of
the Powerwall. "...so £6,808.00 divided by 120 months (10 years) equals £57 a month."
This time though I've included the total cost of the installation and that was included in
the £28,000 total I mentioned earlier. Tesla have actually added a new feature to the app
which allows you to plug in your energy tariff rates and set your peak and off-peak costs,
as well as any monetary values for any export. This then calculates a savings based on how
much solar and the battery has saved. This is great although it's not 100% accurate
in as much as it assumes you've been on the same tariff since the installation. But hey
it's better than nothing! So in the app I've used a super off peak for our peak for our cheap 5 hour
off peak period of 5.5p per unit, per kWh and the rest of the day is peak at 15.33p.
I've set export to zero as we don't get paid anything when we export to the grid.
If you remember the Deemed Export I spoke about earlier as part of our FiT payments.
50% of what we generate we get paid as export regardless to how much we do or don't export.
Our Deemed Export payment is about £150 a year so it's not big bucks as it were.
So this is our Powerwalls lifetime stats right back to the 4th of December
2018. So lifetime self power is broken down by 29% from solar and 27% from the Powerwall.
Which means we have not used electricity from the grid for 56% of our homes energy
over that period of time. The value energy saving according to to the app is £2,743
based on our current tariff. The energy value is an estimate of the money we didn't have to
pay our energy supplier, so savings. We had solar installed since the 8th of September 2011
which means there's an additional 7 years of savings to add into our calculations. The energy
value saving we just looked at only goes back to when the Powerwall was installed in December 2018.
7 years of solar generation that means up until the Powerwall was installed we had generated a
30,262.5 units. This again is energy savings energy that we have not had to buy. If we
calculate that at our current rate of 15p per unit so 30,262.5 units * 15p comes out at £4,537.95p
worth of savings. And just a point on the current value I've used.
It's difficult to accurately calculate historical energy costs over the past 10 years. In the past 3
years we've changed energy suppliers we've changed between 3 different energy tariffs and pricing
methodologies with our current supplier Octopus Energy. And all of these factors make getting a
baseline saving costing quite difficult. Our new 2.34 array solar array was installed in October
2019 and that's generated 5.84MWh and that will be included in the cost savings shown in the Tesla
Powerwall app that we've just looked at. The eddi which heats our hot water which we now use rather
than using gas to heat our hot water. When there's excess solar it heats the water for free otherwise
we schedule it to heat our water for an hour each day during off-peak which is at the 5.5p per unit.
Savings to date from installation in July 2019. £61.67p purely from solar and more solar diverted
to heat our water. The zappi like the eddi can divert excess solar this time into the EVs. Since
installation on the 4th December 2018 the zappi has diverted 3,090 units of
free electricity into the cars. That works out at 3,090 times 15p = £463.50p.
I've also calculated the savings from not having to purchase petrol. I looked
at the mileage on each of the cars. So the Tesla has covered 18,484. The Kona before
we sold it had 14,715. The Renault we've done a 1,066 miles. That brings a total of 33,265.
Say 40mpg in a combustion engine we would have used 831 gallons or
3780 litres. At £156.99 a litre that would have cost us £5,897.80p to travel those
33,000 miles. What about future savings? Will they increase. If we look at the trends since
2010 the UK variable tariff energy prices as you can see has been a slow gradual increase
until we reach 2022 where we see a massive 32% increase in unit costs for electricity.
The current tariff that we're on will end at the beginning of August 2022 and that's just before
the next price cap review in October where energy prices will almost certainly be going up again.
So I think this answers the question will we see better savings going forward absolutely we will.
Let's have a look at the numbers then shall we? Total cost of installation as we looked at earlier
was £28,607.49p. Savings to date; FiT payments £22,681.76p. Solar pre the Powerwall installation
saving of £4,537.95p. Tesla Powerwall and solar savings since installation is £2,753.00.
Eddi for the hot water was £61.67p. Zappi car charging was £763.50p. Petrol savings were
£5,921.96p. Brings a total of £36,419.84p. Which puts us in the black by £7,812.35p.
Which is good. Happy with that. With the recent events going on in the world at the time of
recording this video in April 2022 the instability that's been caused in the energy markets along
with the pressures on fossil fuel prices it's very interesting to see how many people are researching
solar and home storage batteries. Just have a look at the numbers of UK based searches in Google
after over the past 12 months for those following search terms. And so what have we got 'Solar pv'
you can see that spike there from early 2022 and it's a gradual increase certainly in the
beginning of February onwards it's really peaked up to 100. And the interest over time
axis there these numbers represents the search interest relative to the highest point on the
chart for a given region or time. So UK over 12 months in our case. The value of 100 is the
peak popularity of the term value of 50 means the term is half as popular score of zero means
there wasn't enough data for this search term. So that's solar. Well we got there 'solar panels'.
'solar battery storage'
'battery storage'
'Ripple energy' which is the windmill that I've co-opted into. Phenomenal spike in interest in
recent weeks across all these terms. And that can only mean one thing. That more and people
are realising and researching and understanding or wanting to understand is generating and storing
your own energy at home a good thing. And yeah absolutely it is. Is it worth it? Yes it is.
If you can generate at home it's more efficient and it gives you a sense of energy security
so you're buffered a bit by market forces which are outside of your control. If we were starting
from scratch today, no FiT payments and thinking about adding solar and battery storage to our home
we would still make that investment. But you know what are your thoughts?
Do you think rooftop solar and home storage batteries are a good idea or are they just
green washing? Dive down to the comments leave your opinions and let's have a discussion.
Okay thanks for watching and I'll see you on the next video.Ttake care bye.