Anyone want to share costs on batteries?
I am looking at beefing up my battery storage as the ASHP loves power, my solar is big and I have a cheaper overnight tariff.
I've been reviewing batteries and settled on the Seplos Pusung 5kw batteries -
They are LiFePO4, so very stable, they have good storage, 5kw and they can charge/discharge at 100A@51v so 5kw peak in and out. They are also stackable, so I could get 2 and have 10kw etc.
I've also spoken to them and they've told me its $2100 (£1500) per unit for 1, $1800 (£1325) per unit for 6, and $1200 (£900) per unit for 12 plus $350 USD shipping per battery to the UK. If I get them in a big order, it works out very reasonable from a good supplier. I will also need a 5kw hybrid inverter, and this will be £600-£1000
My question is... is anyone else thinking about batteries? If you are, would you consider a bulk order to lower the costs? Using Octopus Go, I could realistically charge 20kW overnight at 5p/kW
One thing to note would be if Octopus goes under or removes the Go tariff you would be left with a system that would only really work in summer provided you can fill all the batteries with excess solar and have expensive batteries doing nothing in winter.
Mitsubishi Ecodan 14kw ASHP + 500l Cylinder
@george there are plenty of other time of day tariffs and EV tariffs from many major firms. Currently my 14kw batteries provide 32% of all my power use. If you can buy them at the right price they make better financial sense than solar panels - which only work when the sun shines and if you don't use the power you give it away to the network operator
I’ve been seriously looking at battery storage, had a quote for Huawei 10kw and 19 405w panels at £14k. Just about to point out to the solar company that the panels won’t fit. There is a market for a decent national solar company.
what inverter are you planning on using?
@mattengineer I've got a Sofar 3000 however that only charges/discharges at 3kw. Ideally I'd like 5kw to take full advantage. Then I'd have 8kw peak capacity. Also if I went 25kw I'd only get 20kw of storage at 80% DoD so I'd need 5kw to fill it at 5p octopus go
@batalto Are you able to parallel two sofar inverters? Giv energy ac coupled inverters can be paralleled (up to 3) but the ramp up of house loads takes a while (c15 secs) so you’re still drawing off the grid.
I’ve got two 80 amp supplies(in phase) coming in to the house, annoyingly western power wanted over £10k to upgrade to full 3 phase which would have been great for inverter choice and ev chargers etc. That could be 4 hours at 80a x 240v could be 153.6kw just need some grid scale batteries. (Wonder if they sell them 2nd hand).
@mattengineer yes from what I've seen you can have up to 3 in parallel.
You would 100% need grid scale batteries. Most inverters take batteries up to 52v at 100A (so 5kw). However they are usually limited less. It's all about the wire sizes as you would know as well as other things.
I looked at 3 phase - they wanted £5k to bring it across the road. Should have bought a house on the other side!
@batalto Curious western power gave me a similar explanation (excuse) that they would need to upgrade the whole ABC from the transfer on the other side of the road.
If I had the time I would build a 16 prismatic cells (280ah) in series to give a 51.2v nominal battery c11.5kw at 80% depth of discharge.

@mattengineer all those batteries are basically exactly that. Just in a nice box with a BMS attached. Pretty sure Seplos actually sell a DIY kit
@mattengineer not for the DIY ones. However I assume it's pretty similar given the weight. $350 per unit and 2-4 weeks in shipping. Could be more now
This is interesting as an alternative to battery storage and potentially cheaper in overall cost.
- 26 Forums
- 2,152 Topics
- 47.2 K Posts
- 75 Online
- 5,671 Members
Podcast Picks
Latest Posts
-
RE: Midea ASHP – how to set weather compensation
@jamespa thanks so much. Very useful
By pash44pump , 5 minutes ago
-
RE: Electricity price predictions
@bontwoody Maybe one for @editor to consider whether a ...
By ChandyKris , 1 hour ago
-
RE: Octopus tariffs - a quick comparison
@scalextrix yes, battery is vital to maximise TOU tarif...
By Tim441 , 1 hour ago
-
RE: What crazy nonsense are inverter limits and why are they imposed?
@howardp99 Yes, I get how the inverter rating is limiti...
By Old_Scientist , 1 hour ago
-
RE: is a home battery without an EV worth it?
You would think, but when I had my Powerwall 3 installe...
By Old_Scientist , 2 hours ago
-
@mars That response surely deserves a nomination for Tu...
By JamesPa , 15 hours ago
-
Specifying batteries, pv solar etc using ChatGPT
I thought I'd try to use ChatGPT to specify my requirem...
By Tim441 , 17 hours ago
-
RE: Ecodan & MelCloud scheduling
When I interviewed Mitsubishi Electric at Installer ear...
By Mars , 21 hours ago
-
RE: Rodents! A word of warning for heat pump owners
@lucia One look at that protection and the rodents will...
By Toodles , 22 hours ago
-
RE: A Customer's Lessons Learnt from a Heat Pump Installation in a Large House
🙁🙁🙁🙁🙁
By Lucia , 1 day ago
-
What is the Heat Geek Guarantee?
We regularly hear from homeowners who are researching i...
By Mars , 2 days ago
-
RE: Help me keep the faith with my air source heat pump installation
@adamk, interesting point. I’ve not focused much on Hea...
By Mars , 1 day ago
-
Intelligent Octopus Flux (IOF) Review
I promised @toodles that I would provide an update and ...
By Old_Scientist , 2 days ago
-
RE: Solar Power Output – Let’s Compare Generation Figures
@julianc Our solar PV has produced more this August tha...
By Toodles , 2 days ago
-
RE: Who's your electricity provider and what's your tariff?
I am pleased to see the change. We definitely need t...
By Jeff , 3 days ago
-
RE: How Do I Know When the Hot Water Has Run Out?
@transparent that is a very interesting suggestion, tha...
By GrahamF , 4 days ago
-
RE: The good, the bad and the not that great – my heat pump installation
Sorry to resurrect this thread, but it is sort of relev...
By cathodeRay , 4 days ago
-
RE: Getting the best out of a heat pump - is Homely a possible answer?
I missed your 22nd June post on this. I am sure it can ...
By cathodeRay , 4 days ago
-
Now posting on the right topic.... With general build...
By benson , 4 days ago