Hello and welcome to Fully Charged. Now
this is a little bit of an update about the Tesla Powerwall and the solar panels
that I have in my house. We did a program about this a while ago, it's been very popular and I have been waiting to do an update when
something has changed and we know more about it. Okay so this is going to
be as quick an explanation as I can possibly do because it is a bit
complicated I drive a Tesla Model 3 as you know
before that I had a Tesla Model S; that means that you have a referral code and
if people use your referral code when they buy a Tesla or lease a Tesla they get
a reduction on the cost of that and in return Tesla give me (or whoever owns the
Tesla) certain benefits.
They don't give you money!
Tesla don't give anyone money, you get things like free super charging or free
autopilot update to your car or you know the different things like that and
eventually through my referral code enough people bought Tesla's that Tesla
rang up about a year and a half ago to tell me I've got a Powerwall for free.
So I was really thrilled! I ring up the installers who did all my wiring and did
the solar panels and the original Powerwall, Joju Solar, and I said "I've got
a free Powerwall! Can you put it in?" And they said yeah and then Western
Power Distributors got in touch so that's the people who distribute the
electricity in the local grid around this area and they said you can't do
The only way I could do it was to have a three-phase upgrade to install
three-phase which is what you would have generally in an industrial unit not in a
house although lots of houses are being built now with three-phase already
connected and in other European countries people have three-phase as
normal anyway it's quite unusual in this country so I went "Fine, let's do three-phase!"
Oh my god, it's gonna cost a fortune. It was not cheap but that will explain the
previous episode we did about the JCB electric digger; that's why I had to dig
a trench to lay in the cable so that we could have three-phase connected to the
house it was a new cable that was installed eventually it was connected
and now it's been switched on for the first time and thank goodness it works!
So we've got lights in the house, we've got three-phase coming in we've got new
chargers all sorts of other things which I'll explain later on so that's how I
got to this point so yes, I was given a free battery by Tesla
but my goodness that was the most expensive free gift I've ever been given! So Chris it's been a while since we
both stood in this garage talking about my original Powerwall which has been
It hasn't gone wrong, it's done what it's meant to do
which is very encouraging but I just for a start, want to thank you
for working out how on earth to do all this because this is an absolute monster, it's turned into a monster project hasn't it? What happens when we look to do a Tesla
Powerwall installation is that we'll make an application to the local grid
operator to see if the network is up to hosting this new equipment and 99
times out of 100, the answer is yes absolutely fine.
In your case you
are the one in 100 where actually some kind of reinforcement was required in
order to in order to host all of this. I think it's up to 11 kilowatts of solar I
can now install because this system can now deal with that kind of power which
is really good. Yeah that's the advantage of upgrading the supply
into the property, to be able to take more power the other important
change that's taken place there is that your original supply was what's called a
'single-phase supply' which essentially means that there's you know one wire
running into the property.
You're now on a 'three-phase supply' which
essentially put in three live wires. That obviously increases the capacity of
what we can do here. With the Zappi charger, that's now a twenty two kilowatt charger, there's
no way you could have that on a single-phase. Exactly so the
three-phase supply that you've got coming in has also allowed you to
upgrade the electric vehicle charger, the Zappi charger, up to a three-phase device
which will allow you to charge the cars even faster than you could before. So I just want to mention that
the Tesla… this is called the the Signature Powerwall, that's what
it's called and on the Tesla website it's signed by Elon Musk… He
doesn't like me!
He's not done it has he? It's personal I think. I'm taking it as a
personal affront he didn't want to sign mine but then so what we've got now in
total storage and is somewhere around 26 kilowatt hours, is that right?
Yup so they're thirteen point four kilowatt hours each , so you're
now up to twenty six point eight kilowatt hours of storage capacity and I
think it's worth relating that I suppose to the size of the solar PV
system that you have here so you've got a five-and-a-half kilowatts solar PV
In the middle of summer on average that would be producing about
twenty seven and a half kilowatt hours per day. I've had a lot of mid-30s…last year in particular. Certainly on a sunny day you would have beyond that but the average summer day would completely fill both of them. I think now we're
talking November time/middle of winter… I think the Sun is probably only going to produce enough to sort of half fill
one Powerwall and that's really to do with the you know seasonal
variability of solar in the UK. Obviously some of your viewers in America and
Australia are gonna have a lot more supply.
Yeah, so unfair! The way we've sort of
designed this system is essentially to tier up where the solar should go
so when you're producing solar the first place it goes into the Tesla Powerwall
and it fills those up. Once they're completely full then any excess will go
into the Zappi car charger and then directly into your car and then if the
Zappi is not plugged in or if the car is full then any excess solar instead of
going back to the grid is actually dumped into your hot water tank through
through what's called an Eddi device, also made by the same people that
make Zappi, and sort of working in very much the same way so what you're really
ensuring there is that of all the solar that you generate, you're not
wasting any, you're really not spilling anything back to the
grid at all and you're getting the most usage you possibly can out of the
solar that you've got on your roof.
I think it's worth
pointing out that it's quite an unusual thing in the UK to have three-phase
connection to a house… If you look at the wires running down the street they are three phases. If you go somewhere like Germany they will tap off
all three phases into every single home whereas in the UK we just pick
one at random and wire it into a house and so it will go; phase on this house,
phase two on the next and so on down the street. There's certainly a lot of talk about new build
houses now having three phase as standard I've certainly been reading
things about that that it's going to become more common here.
Yeah I think it's
likely to become more common and I think yes certainly the desire to charge
electric vehicles quickly is probably gonna drive more three-phase supplies
going into new build properties in coming years.
For existing properties,
obviously they function just fine on single-phase. I don't want your viewers to think "I got to upgrade my house to
three phases" cuz that's just not a normal thing. No, that is not normal. So you
certainly can have, like we did for three years; a Powerwall on a
single-phase lot with solar. The big difference I think which is what a lot
of people asked about when we did the first episode is: "What happens if there's
a power cut and you've got a full battery?" and the answer then was you
can't do anything, you know.
We've experienced that in the time we've
had that battery we've probably had two or three power cuts and we have no power
and yet I know the battery has maybe got 10…12 kilowatt hours of juice in it but
we can't use it. So now we can!
Yep so I think that's something that Tesla realised is that, and it certainly came out very
clearly on the comment section of the last video that we did with
you was; "You've got a full battery in your house and you can't discharge it when there's a power cut?"
That's kind of nuts! The idea that you would put in
a device to ride through a power cut when in the UK we get maybe five minutes
of power cuts a year…
…Well, that doesn't make sense.
But if you've got a battery in your house that you're using to
store solar then why wouldn't you incorporate that functionality to allow
you to ride through a power cut as well. What Tesla have now done is
they've bought out what's called the Backup Gateway which is a device that
does allow you to run off your batteries when there is a power cut.
Now the reason behind that is again to do with the electrical regulations
within the UK. Broadly what the grid would say is "If there is a power cut on the grid, our guys need to go and work on those wires and we can't have
people's solar panels and people's batteries in their homes potentially
making that grid live while people are working on it". Most solar householders will will know this that when there's a power cut their solar inverter will turn
off and historically the batteries would also have to to turn off
The way that they get around this is that the Backup Gateway
is constantly monitoring the voltage on the grid and if it detects that that
drops out of range or drops to zero then there's a relay in there that physically
disconnects the whole house from the grid. And once you've got that
physical disconnection of your property from anything that's going on out
grid side then you are allowed to run off these batteries behind that switch So Mark now you're the genius who's
actually put this system in I've been watching you with enormous admiration
because I don't know you've managed to work it all out because it's pretty
complicated but I'm really impressed with what you've done but what we're
going to try and do now is actually test out what happens when there's a
power cut. Exactly that. So hopefully we'll disconnect the switch here, we'll simulate that we're going to lose a connection from the grid and then
hopefully behind us here we'll see the links they may flicker, they may not.
Hopefully they will obviously remain lit And then we'll be on backup.
So we're going to try it
out now, I'm quite nervous.
Here we go… takes a few seconds… you can hear the switch clicking in and there we go… It should start to operate in a second.
We got a flash then! There!
And we're on! We have backup from
our Tesla Backup Gateway. So it's quite interesting, because that is the first time I've seen it. So effectively we would probably lose the lights for a couple of seconds in
the house but then it would all come back on. That's right.
So now we're running off the battery's? Solely off the batteries.
Wow that is amazing, that is
amazing. Wow! I think I had in my mind you know "Oh you have to have a Backup
Gateway" and I imagined it would be this size like that, it would be this tiny
little switch in the fuse box and I didn't realise it's quite a big chunky
It's quite a big chunky thing I think they've done something very cute
there by making it look like a mini Powerwall but obviously you have to take
the whole electricity supply through your house through here in and out again
and through that switch so there is some you know quite hefty electronics
within the gateway as well as all the sort of smart control and operation
of the batteries that it does as well.
You can set the Tesla Powerwall
to charge up with cheap night time electricity so if you're on a tariff
where you pay more in the day than you do at night which is very very common
for electric vehicle owners then you can top up your batteries with cheap night
time electricity. Obviously you don't want to fill your batteries up
with cheap night time electricity because you won't be able to get the
next day's solar in. So what the Gateway does is it actually
makes a prediction of how much solar it is expecting to put in tomorrow…
Oh I didn't know that, wow!
…and tops up the rest with the cheap night-time electricity leaving enough
space for what it takes to come along tomorrow.
That is cleverer than…
Obviously it's not super accurate, it's not taking in a
weather forecast for example, but it can essentially monitor what it is doing
roughly at that time of year to get to a pretty good approximation of how much it should charge.
So it's a pretty big step up then, it's not just just a big switch that means I can have
electricity in a power cut, it's much more intelligent in that? Yes so that that's
really less to do with the Gateway and actually more to do with the firmware,
the software that the Gateway is running so anyone with an existing Gateway can set their Powerwall to run in that mode. Once I understood
how to use it, once I was used to using the software my aim was to never
use grid power between four o'clock and eight o'clock at night.
You know, to
manage it so that even in the winter I charge these now with off-peak
electricity in the night so I think they switch about half past midnight, they
charge. But what that means is even in the middle of winter when there's
minimal solar I then try and run the house as much as I can off that but
manage it so that we definitely don't use it at the peak time which is when
electricity is the most expensive and the dirtiest. And that's been an amazing
feeling to do that you know that will be easier to do because that's my argument
is you know I'm definitely in a privileged position at the moment to be
able to afford to have those and to be able to afford to put this in but as
the prices come down you know and more people have batteries you know it
is that it's a simple argument if there were 20 million homes with even a four
kilowatt hour battery or quite a small one, no solar but they charge them off-peak and
they use them at the peak that peak goes down you know it's that's as simple as
that you're leveling out those ridiculous highs and lows.
And when you realise that top peak is the dirtiest and most
expensive electricity we produce it really makes sense in a big way. In fact as we discussed many
times we don't get that many power cuts but when you do get one if this is the
result it's brilliant.
Absolutely and if you've got solar PV then why not. When the feed-in tariffs were in place
you were paid the feed-in tariffs for what you generated, so any unit of
electricity that you generated you got paid for.
Even if you used it yourself to boil a kettle or whatever.
Anything that was exported back to the grid you got paid
five pence per kilowatt hour for as a flat rate and in most cases
you know it wasn't even measured they just said well half your electricity is
going back to the grid and you get 5p for that.
Since the removal of the feed-in tariffs that export payment has also disappeared
and is going to be replaced with something called the Smart
Export Guarantee which will be coming in place first of January and
that basically says that different electricity suppliers can offer you
different export tariffs and the idea is to sort of create a market between
electricity suppliers to take any excess solar that you might spill back to
the grid right so it's a bit more complicated than just giving everyone a
flat 5p you're actually going to have to shop around and try and find the
best deal you can buy for the electricity that you export.
also need a smart meter to be installed to actually measure that exported
electricity accurately. But then there's a variable one
which follows the wholesale electricity price because that is the thing I always
remember that when I first realized that electricity didn't always cost the same
the wholesale price you know that and the variations in that go from
effectively sometimes negative to really high and so if you can sell electricity
at the peak yeah I'm thinking if you can buy it when it's cheap I think that's
perhaps where we're edging towards so I think the majority of suppliers under
the smart export guarantee are going to be offering a flat rate but I think you
will see some of the smaller players doing
interesting things around time of day pricing yeah we're beginning to see you
know people charging different prices at different times a day or for importing
electricity and we'll probably also see them doing the same for for exporting
and electricity so now on the system we've got now if it's a this happened in
the middle of a sunny day in the summer and you had a power cut would we still
be getting with the inverter still be running so we'd still be able to take
this solar in – absolutely so the inverter would operate also right and so
the battery would it would obviously use up a certain amount of energy and then
once it's got to about 30% and the battery the inverter would then kick in
I see all right so then it would start to either recharge the battery will run
that's right okay I think that's really the next stage for domestic battery
evolution if you like the moment they're there to allow householders to capture
their own solar and use it for themselves the next stage will be for
householders to capture the solar and use it for the benefit of the wider grid
and that's only going to be facilitated by having these smart tariffs in place
what people will find difficult is I think that you know the idea that they
might get paid five or six P for the electricity that they put out to the
grid but they know that they buy in again at fifteen or twenty pence.
Yeah people will be looking at that and going well why why is there that difference
the answer that is is that you know the five six P is is the the value of the
electricity itself the value of the electricity is it might be produced by a
gas five year power station or an offshore wind turbine or so forth and
the rest of your bill is things like paying for the National Grid infrastructure.
The substations, the wires the pylons… paying for the metering paying
for the billing and obviously the utility profits in there plus any sorts
of green legislation so the moment we're seeing all of those costs bundled onto
your import price but don't you don't get that much that when you export your
grid is so new that price differential between
the price you pay for electricity to import it versus the price you get to
export it you know that is where the real value of the battery comes in so that's all we've got time for for
this episode of flinch I hope you enjoyed it I hope you learnt how this
technology is developing how it's you know it's still expensive it's still
being developed but you know the Tesla gateway the backup gate has only been
out since April this is very new stuff and all I've got to do really now is
make sure that my signature power wall which is what I was told signature with
that word in the title it's going to have a signature so thank you very much
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Right that's it… This is how he signs it. Look at that
that's it…. Signature Powerwall, nice!.