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Exporting at 15p - Help please
- Thread starter PITA
- Start date
I think we've found just how valuable IO control is to Octopus. A few hundred quid must be nothing vs what they save moving car charging around at night.
It's new as of this week, hence the flurry of posts. Until this week you could only use the 'SEG' export at 4.1p with an EV tariff like IO, Go, now we can have either their fixed export at 15p, or Agile Export at a variable rate. Announced on Monday, all switched on Thursday.
Last weekend I could use my solar for nothing and guilt free, now it feels like it's costing me 15p to do so, my brain is struggling to rationalise this as a positive thing.
People use home assistant to stop their cars discharging their batteries, including power walls. One you have all the devices integrated, you can make really simple if this then that automations to stop the batteries discharging when the car is charging.
It's a flawed way of thinking.
Solar isn't "free". You have the sunk cost of the panels and install - divided by the lifetime generation = a cost per kWh. It's not free.
My lifetime generation estimate gives me an all in cost of 9p/KwH - so happier now I can sell to grid at 15p (which will rise in coming years with inflation). As opposed to the last year or so where I was making an effective "loss" per kWh exported.
Oh yes it is...
I'm actively tracking our Solar Generation and we consume 98% of it during the year, because we manage it all through 187 kWh of battery storage.
The cost saving at peak-rate will have our Solar Array fully paid for in 6 years.
I'm half way through, so in 3 years time those panels will be paid for and then producing 'free' electricity. There is no Operational Cost expenditure.
Then, I've 'only' got another 19 years to rake in my FREE electricity under the Warranty Period.
In 2026 I'm renaming the Sun to 'Free'
Look at that beautiful Free in the Sky today
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The simple option is to split the main cable before the powerwall sensor, so the powerwall does not see any electricity the charger uses.
That's how we've done it.
Our two 22kW chargers are wired to a 3-Phase consumer unit which is immediately after the Grid Meter.
The Powerwalls, house Consumer Unit and Gateway are further down on a Single Phase. So that lot cannot see the two 3 Phase chargers.
This means the house & Powerwalls operate independently to the fast chargers.
ACarneiro
Active Member
Eh?
I’m not sure that they know that I have a battery.
And as mine is unable to export to the grid anyway, I don’t really see what it changes for them?
ACarneiro
Active Member
If you want to play "The MCQ Game", if you only have Solar then technically the "most relevant option" would be Solar and Storage
See to me last week if you consumed a kWh you were losing out on 4.1p, practically nothing
This week if you use a kWh you are losing out on 15p, definitely more.
the cost of installation hasn't changed, so cancels itself out in this comparison.
phil4
Member
Yeah that's how I do it, there's an IO plugin which when queried will tell you if you're in a "cheap" slot. So poll that outside of the normal 23:30 and if it is, either bang the PW to 100% and let it charge too, or set to Self Consumption and it's target/backup threshold to the same as it's charge.
To be honest though, although I've set all that up, I so rarely see extra slots I don't normally bother it.
I am thinking about purchasing a PW.
Is it honestly that good? So you just self enter the buy and sell rates and it will automatically work out what to send to grid and what to use for the house? Theres no special config you need to do in app / tell the app to do it this way?
Thats honestly really clever.
Not really, as the Octopus rates now removes the need to predict the PV output, so just need to predict house useage for rest of day (until cheap rate) to decide between export and charge battery.
ACarneiro
Active Member
As seem to be the case with most Tesla products, Powerwalls were pretty much first on the market with a really good solution. They’ve got good tech specs and are well built.
Problem is they haven’t been updated in a number of years and it shows.
The competition are coming up with products that are similarly good and significantly cheaper (and many based on LiFePo chemistry which, in principle at least, should last longer).
The latest GiveEnergy products are probably worth having a good look at.
Problem is they haven’t been updated in a number of years and it shows.
The competition are coming up with products that are similarly good and significantly cheaper (and many based on LiFePo chemistry which, in principle at least, should last longer).
The latest GiveEnergy products are probably worth having a good look at.
phil4
Member
As said above, GivEnergy have an AIO solution which is as good as or marginally better then a PW on paper. It's early days though, so some features aren't available yet, or don't work as planned yet. It's cheaper though. So if you were buying now, you'd want to take that decision.
On the PW side, as stated as Octopus have changed the rules, it's made the PW (or any setup for that matter)'s job easier. On a PW you have very little control over what happens, You tell it what you want to achieve, self-powered or time control. The former will absorb all solar and use it to power the house, the later will work out the cheapest way to work.
You enter your prices and times in, and the both of them will charge if they think they need to in the cheapest slot. The Time based one though will power the house with the PW (which was charged at the cheap rate) while exporting all the solar... uness it thinks it'll run flat, and then it''ll share the solar.
There's also a slider to set the percentage to save for "backup", ie. when there's a power cut it'll run on battery (and solar), so the slider sets the lowest level the battery will discharge to normally, so as to "keep some".
In theory the PW learns your daily usage pattern, and predicts the solar, so when not aiming to export all solar it tries to charge enough to power the house with the predicted solar, during your off peak. Some find this works really well, some less so. You can use that backup reserve slider to for charge the battery if you think you have a better idea.
But that's the gist of it, there's very few controls exposed and most of the work is done by the PW with a little room for you to force a little control if you wanted.
On the PW side, as stated as Octopus have changed the rules, it's made the PW (or any setup for that matter)'s job easier. On a PW you have very little control over what happens, You tell it what you want to achieve, self-powered or time control. The former will absorb all solar and use it to power the house, the later will work out the cheapest way to work.
You enter your prices and times in, and the both of them will charge if they think they need to in the cheapest slot. The Time based one though will power the house with the PW (which was charged at the cheap rate) while exporting all the solar... uness it thinks it'll run flat, and then it''ll share the solar.
There's also a slider to set the percentage to save for "backup", ie. when there's a power cut it'll run on battery (and solar), so the slider sets the lowest level the battery will discharge to normally, so as to "keep some".
In theory the PW learns your daily usage pattern, and predicts the solar, so when not aiming to export all solar it tries to charge enough to power the house with the predicted solar, during your off peak. Some find this works really well, some less so. You can use that backup reserve slider to for charge the battery if you think you have a better idea.
But that's the gist of it, there's very few controls exposed and most of the work is done by the PW with a little room for you to force a little control if you wanted.
I get that this feels right, but it doesn't really offer anything clever. There isn't any difference in price between the power in the battery and that from your panels. I let it keep my battery full in the day then discharge excess from a battery to the grid just before you recharge in the cheap rate, achieves the same or better return.
PowerWall / GivEnergy All-In-One will always be more expensive than adding batteries to an existing inverter. The are nice solutions, but you are paying about £500/kWh, I can buy batteries for about £350/kWh for my GivEnergy Hybrid Inverter.
phil4
Member
That's because you can export from the battery. I'm not permitted by my DNO. So my only option is to export solar as I go, and use the battery to power the house.
I can't add batteries to my existing inverter, so that isn't an option, and hence doesn't matter if they're cheaper.
I'm not trying to sell PW, I frankly couldn't give a t*ss if someone gets one or doesn't. I merely provide info on how it works and how I find it so people can make a more informed decision that basic it on sales and marketing info.
The whole solar, battery thing is horses for courses, what works for me won't work for others, and what they prioritise as the most important things will be different for me. As I say, I say the things I say so people can work out if it works for them, or not.
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