Wait for Powerwall or go for alternative? High electric usage
Hey everyone
We are a fully electric house. Plus we have a holiday let attached to our supply.
Last year on some days in Jan we pulled over 120kWh of electric in a day. Approx 60kWh for ASHP then the rest split 50/50 between house and holiday let.
Im going to do some work to hopefully optimise the ASHP consumption. But as we have PV I’d also like to explore batteries and charge them on our aoxtopis Go Faster 5 hours at 8.25p
i placed an order for a Powerwall back in March but still don’t have a date. Just a few emails saying they were very delayed. I don’t think it’s going to arrive this year.
alternatively I’ve seen systems such as Solax which give you 25kWh for about £15k (Powerwall is about £9k) so about the same price per kwH
Has anyone any experience of Powerwall vs other systems? Is it really much better or is that just branding?
250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.
Apart from the control system and app, they all do the same thing. You can build a 15kwh for about £2.5/3k with cells and a BMS box. Also worth noting that a powerwall uses lithium ion cells like a car, most other batteries use lifepo4 batteries (which are heavier, but far more stable)
Posted by: @bensebIs it really much better or is that just branding?
If you have a Powerwall and solar panels then you can sign up for the Octopus Tesla plan which is currently around 26p/kWh plus 45p/day standing charge and is symmetrical. Note that the price used to be much lower, per post in April this year, so the price rise does indicate that the Powerwall is more defined contribution rather than defined benefit.
Posted by: @chickenbigPosted by: @bensebIs it really much better or is that just branding?
If you have a Powerwall and solar panels then you can sign up for the Octopus Tesla plan which is currently around 26p/kWh plus 45p/day standing charge and is symmetrical. Note that the price used to be much lower, per post in April this year, so the price rise does indicate that the Powerwall is more defined contribution rather than defined benefit.
Yes to be honest when it was 11p/11p that was our main reason for wanting a Powerwall. Running the ASHP at 11p wouod be amazing
Now it’s 26p the shine has gone. We’re on Go Faster at 30p/8.25p so currently that’s cheaper overall.
Will see how things go in the winter but I think the main priority is any battery over no battery! Don’t think there’s a chance of the powerwall arriving before 2024.
250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.
120kWh of electricity a day is rather high; a reasonably sized battery would struggle to make a dent in the bill from this. To what extent have you tuned the ASHP settings? Also how much of the non-ASHP usage is for your cars and how much for domestic?
DIY storage costs alone are approximately 2700 USD for around 14kWh (e.g. a Seplos Mason for 500 USD with 16x 280Ah batteries for 2200 USD). Assuming 90% efficiency you are looking at £2.70 a day of savings from this battery, so 2 1/2 years to break-even. I've not been following vehicle-to-grid posts on this forum as I'm not a car owner ...
We are also fully electric (9,000 kWh per annum) and also placed an order for a Tesla Powerwall in March and are not expecting it to arrive until 2023.
Don't know your usage and demand, but:
Although 120kwh per day, it is not technically 120kwh from battery as while sun is shining and you have enough panels. You'll be charging the batteries for nighttime and running loads direct from the Inverter and Solar, so in theory - 60 to 80kwh batteries would suffice.
This is similar to a project I am currently working on.
Oversize the solar to charge and power then run the batteries down overnight or during heavy loading.
Don't oversize battery/Solar that payback is long, there is a balance where some Grid is OK as chasing 100% Solar / Battery would be inherently expensive.
Aim to do the heavy stuff on sunnier days and around 11am to 2pm if possible.
I can explain further if needed..
That’s our winter load so very little PV at that time.
in the summer we only pull about 15kWh from the grid without batteries due to evening meals etc that are difficult to shift. Now we’re on Octopus Go the cost of that is minimal.
So not really much way to reduce battery need in Winter. I think we’ll get 20-30kW to reduce things down a bit in winter as we don’t want a huge expensive array that’s useless in summer.
250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.
- 26 Forums
- 2,255 Topics
- 50.2 K Posts
- 760 Online
- 5,915 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: Testing new controls/monitoring for Midea Clone ASHP
Home Assistant also has an auto-entites card so you can...
By Grantmethestrength , 17 minutes ago
-
RE: PV Panels on roof in Conservation Area
@jamespa Thanks for the input James, recording Oil usag...
By colinc , 43 minutes ago
-
RE: Midea ASHP – how to set weather compensation
@dgclimatecontrol - you have awoken me from my several ...
By batalto , 59 minutes ago
-
RE: Help me keep the faith with my air source heat pump installation
@jamespa mine seems changing albeit not by much, 3.21, ...
By AdamK , 2 hours ago
-
@majordennisbloodnok The migration hasn't started in th...
By HCas , 2 hours ago
-
RE: Radiator Sizing Dilemma: Vertical vs Type 33 for Low-Temperature Heat Pump Systems
Yep that's it, but the current design would re...
By DREI , 3 hours ago
-
RE: Buying large amp bidirectional RCD and RCBO
There won't be many RCBOs with a 100mA trip rating beca...
By Transparent , 3 hours ago
-
RE: Electricity price predictions
Because its what the investors demand, simple as that. ...
By JamesPa , 4 hours ago
-
RE: One room is colder than the rest of the house
@jamespa thanks for all the advice. Just so you know, ...
By AndrewJ , 6 hours ago
-
RE: Mitsubishi Ecodan R290 10kW performance
@dgclimatecontrol I only have 1 cylinder and I can conf...
By Ecoste , 6 hours ago
-
RE: Daikin Octopus installation update - I saw my first defrost. 😍😂
My MMI is in the loft but I checked the pump flow rate ...
By RadWhisperer , 7 hours ago
-
RE: Grant Aerona 3 and Drayton system questions
Good man/woman that plumber! Very likely....
By JamesPa , 7 hours ago
-
RE: New build installation query
@paullacey Hi I have managed to save the fil...
By JamesPa , 8 hours ago
-
Thanks for the response @batpred Your conversational ...
By Transparent , 10 hours ago
-
RE: What should we do with our Aga?
One slightly off-the-wall suggestion is that, if you li...
By Majordennisbloodnok , 11 hours ago
-
RE: My experience with 3 heat pump surveys: Heat Geek, British Gas & Octopus
If you paid for any of the assessments try asking for t...
By JamesPa , 1 day ago
-
I've created a separate post here, wondering about radi...
By DREI , 1 day ago
-
RE: Air source heat pump roll call – what heat pump brand and model do you have?
@ecoste, @walnut-tree-cottage these are both great piec...
By JamesPa , 1 day ago
-
RE: Solar inverters - where does the energy go when clipping?
You will, of course, check the dimensions and weight be...
By Transparent , 1 day ago


