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Octopus quote to add battery to system
Octopus quote to add battery to existing solar system
Just looking for some advice please.
We already have solar and are wanting to add a battery. Octopus have quoted us £3,134 for a 5kwh Enphase battery.
For various reasons, I haven’t been super impressed so wanted to get your view on the price and also whether a 5kwh battery is the norm or if a 10kwh battery is the norm. (4 bedroom house). We have an electric car though 90% of the time it sits on the drive, we don’t have to charge it often.
I appreciate any views or considerations.
Many thanks.
ETA Octopus didn’t mention an inverter so I assume that’s ok. The one below is what we have but I don’t know what this is!
ETA 2 I need a new inverter so this would include the cost of this.
I have had an independent quote £6.6k for 10kwh which includes a new inverter. Not sure on price but maybe I’ll go with them as losing confidence a bit with Octopus, maybe unfairly.
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20 Replies
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Fox EP 11/12 10kWh approximately £3k
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Is that quote including a enphase inverter or do you have an enphase inverter already?
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They don’t mention a new inverter so assume the one I have is ok…
I checked and I need a new inverter. I assume the price reflects this – a new inverter and 5kwh battery.
But am getting more and more convinced that I need a 10kwh!
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Not that many people offer enphase, not sure of if its cost effective for many. Of you.was going for new inverter and battery , the world is.your oyster
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What inverter do you currently have? A 5kw battery will get you very little in terms of performance
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My current inverter wouldn’t work for a battery so would need a new one. I assume this price includes that.
I’m also thinking more that we need 10kwh, thanks!
This is a photo of our inverter currently. I don’t really understand it to be honest. They didn’t mention a new one but did ask for details on this.
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10kw is what we have ideally I’d love 15kw but we have a heat pump and use a lot of electricity
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Few more details about your current set up might help get more information specific to yourself.
How much are you exporting a day currently and how much are you importing?
Do you have a hybrid inverter with your panels or will the battery be installed separately (AC coupled)
A key one to determine, are your panels on a FIT scheme?
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2025 import = 4,990.73kwh / 365 days = 13.67 per day though it obviously changes hugely by month.
2025 export = 2,175.21kwh / 365 days = 5.96kwh per day
This doesn’t include the solar we actually use, just figures from Octopus app.
I am unclear re the inverter. I added a photo to the post which I sent to Octopus. They haven’t mentioned an inverter to me.
No, we got the panels fitted in 2022 so no FIT scheme.
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I have 2 x 9.5kWh givenergy batteries, 5 bed house. However the size of battery you need should be based on what you need. I looked back over the last year and used my largest 10 days as the target and added 20% on top to factor in increases in usage and loss over the lifespan of the battery
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For comparison, we are currently offering a 20kWh of storage for £3200 supply only
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5kw is not much power. My 3 bed small 120sq m house uses about 10kw a day general usage and another 15kw in winter for ashp. For just battery prices you can start with a fogstar based in the uk with 16kw battery from around £1500 but you also need a hybrid inverter. If your system was fitted as pure solar without batterys. You will be looking at the price of the hybrid inverter plus installation.
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When you can get 16kWh first under £2k it does make you wonder how Octopus can get away with such pricing. Definitely shop around. NB: if your inverter isn’t near an outside space then siting the battery is likely going to problematic. It’s not mandated yet but strongly recommended that batteries are not installed inside a home now.
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Oh a sofar inverter. Haven’t heard good things about them, apart from lots being replaced, if.you have access to ev and either car or charger is Compatible with a tariff like Octopus Intelligent Go, it may make sense to invstigate.what usage is and when, you may find that a new inverter and bigger battery would enable you to grid charge overnight at off peak rates, then cover baseload till solar yield takes over, then solar covers baseload and hopefully power the house untill off peak starts again !
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That’s extremely expensive. You can get a 16kWh Fogstar package for that with a 6-8kW inverter. 32kWh is £5500~
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5kwh is just plain silly, 10kwh for 3 bedroom semi, 4 bed det you probably need 15kwh plus, easy thing to do is take your annual consumption your supplier will give you this deduct EV usage, most charging app will have your annual usage I have “Ohme” and that does, 5000/365=13.699 average daily usage.
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Your inverter is not a hybrid, so you’d either need to replace it or add an extra battery inverter (or a hybrid if you’re thinking of adding more solar panels in future).
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Since you’re on IOG you can fully charge a 15 kWh battery in the 23:30-05:30 slot at 7p per kWh. Thus, allowing for a 10% SOC, that means you’ll have 13 kWh available to the house daily (which would otherwise cost you ~30p per kWh).
Therefore find someone who can supply & install a 15 kWh battery for under £5K to your existing hybrid inverter.
I have a Heat pump so I went for a 30 kWh battery. Also on IOG. All works fine.
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if going heat pump later defo not enough. if not then 10kwh min, probably wont actually get that out of it with losses anyway. its why tesla powerwalls are 13.5kwh as this is fairly normal usage. our 4 bed uses about 10kw without solar offset. weve got 27kwh and when it was -6c that was empty by 4:30pm.
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Im a DIYer so it doesn’t count but… I just installed a 5kw Soluna battery for £775. The hybrid inverter (you need one of these) was about the same price or less. A couple of hours work later… I found one view that the battery should be twice the capacity of the PV array. I have a 20kw Pylontech array being driven by a 5.6kw pv array. In winter I have to top the batteries from off peak grid. Costs me a couple of quid. A good bet as then most of the days consumption is at 8.6p and not upper 20’s. In summer there is an excess although most tops up the 2 EVs.
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