Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!
Home battery, EV and solar considerations (Fogstar/Sunsynk/Zaptec Go2/Polestar 4)
Hi all - It would be great to get your views and advice on my fully electric home setup (inc 12kw ASHP) and future proofing for V2G and V2H.
I have a solar installation pending installation: 19xAiko 475w panels (9kw), 32kw Fogstar battery, 10-12kw Sunsynk inverter. G99 came back ok with an 8kw export cap.I will also be taking delivery of a Polestar 4 next week which has a 100kwh battery and is V2G/V2H ready, but not yet enabled. I have selected the Zaptec Go 2 home EV charger because they partner with Polestar and it is V2G/V2H 'ready'.
Whilst the 32kwh Fogstar battery will cover 90% of our home energy usage, it would be good to enable the car battery to be used to power the home if the battery is depleted (i.e. on the coldest days when the ASHP usage is very high). I'd also want to benefit from any grid load balancing schemes and allow my car battery to discharge to the grid to increase export payments when available. What is the best way for this to be configured to enable this approach when V2G/V2H is enabled?
I'd also value thoughts on the best tariffs for this setup (Octopus Intelligent Go?)
Any thoughts and advice welcome.
Thanks
Posted by: @webcmgHi all - It would be great to get your views and advice on my fully electric home setup (inc 12kw ASHP) and future proofing for V2G and V2H.
I have a solar installation pending installation: 19xAiko 475w panels (9kw), 32kw Fogstar battery, 10-12kw Sunsynk inverter. G99 came back ok with an 8kw export cap.I will also be taking delivery of a Polestar 4 next week which has a 100kwh battery and is V2G/V2H ready, but not yet enabled. I have selected the Zaptec Go 2 home EV charger because they partner with Polestar and it is V2G/V2H 'ready'.
Whilst the 32kwh Fogstar battery will cover 90% of our home energy usage, it would be good to enable the car battery to be used to power the home if the battery is depleted (i.e. on the coldest days when the ASHP usage is very high). I'd also want to benefit from any grid load balancing schemes and allow my car battery to discharge to the grid to increase export payments when available. What is the best way for this to be configured to enable this approach when V2G/V2H is enabled?
I'd also value thoughts on the best tariffs for this setup (Octopus Intelligent Go?)
Any thoughts and advice welcome.
Thanks
The immediate point that sprang to mind reading your setup is whether either the charger (which isn't a brand I'm familiar with) or the vehicle itself is compatible with Intelligent Go, as it's a requirement to have one of these to be able to switch onto it. I agree that it's likely to be the best tariff for your setup, so compatibility with it would be an essential factor to consider.
As for the V2G/V2H plans, I suspect that we're still some way away from these becoming a reality for use in the way that you envisage. Short-term, given the price of the Fogstar batteries, it would be relatively cheap to increase the capacity of these further to cover any excessive heat pump usage, depending on your views as to how quickly the V2G capability will take to become usable reality.
130m2 4 bed detached house in West Yorkshire
10kW Mitsubishi Ecodan R290 Heat Pump - Installed June 2025
6.3kWp PV, 5kW Sunsynk Inverter, 3 x 5.3kWh Sunsynk Batteries
MyEnergi Zappi Charger for 1 EV (Ioniq5) and 1 PHEV (Outlander)
User of Havenwise (Full control Jun-Dec 2025, DHW only from early Dec)
Subscriber to MelPump App data via CN105 Dongle Kit
@sheriff-fatman thanks for the comments, I checked the link below and it suggests the car is compatible with Octopus Intelligent Go, but not the charger (the Zaptec Go isn't and the Zaptec Go 2 is not listed yet). I assume this will still be OK on this basis?
I appreciate V2G might not arrive soon, but I thought it best to future proof as far as possible?
https://octopus.energy/smart/intelligent-octopus-go/
Posted by: @webcmg@sheriff-fatman thanks for the comments, I checked here ( https://octopus.energy/smart/intelligent-octopus-go/) and it suggests the car is compatible with Octopus Intelligent Go, but not the charger (the Zaptec Go isn't and the Zaptec Go 2 is not listed yet). I assume this will still be OK on this basis?
Yes, a compatible car will be fine to qualify for the tariff. The basic requirement is that you do a form of smart charging from it at least once every 30 days, or something like that.
130m2 4 bed detached house in West Yorkshire
10kW Mitsubishi Ecodan R290 Heat Pump - Installed June 2025
6.3kWp PV, 5kW Sunsynk Inverter, 3 x 5.3kWh Sunsynk Batteries
MyEnergi Zappi Charger for 1 EV (Ioniq5) and 1 PHEV (Outlander)
User of Havenwise (Full control Jun-Dec 2025, DHW only from early Dec)
Subscriber to MelPump App data via CN105 Dongle Kit
Thanks, I've gone for the Andersen Quartz rather than Zaptec to be on the safe side with the charger compatibility. It's so difficult to know what tariff to go for with the EV and high usage Heat Pump...
Posted by: @webcmgThanks, I've gone for the Andersen Quartz rather than Zaptec to be on the safe side with the charger compatibility. It's so difficult to know what tariff to go for with the EV and high usage Heat Pump...
I doubt you'll find anything better than Intelligent Octopus Go in terms of minimising overall costs. During this winter, my highest heat pump usage was in January, during which the overnight stored battery charge (15kWh) was depleted by around midday. My peak blended tariff rate per the Octopus bill was 12.47p/kWh for that month, so the increase from the base 7p/kWh rate at the time was less than I expected.
You'll be starting with more than double the battery storage, so should be able to achieve a smaller increment than this. The rates have changed from 1st April, but the principle will be the same. By fortunate timing of when my fixed rate renewal window opened I've got 22 days in April with an off-peak rate of 3.5p/kWh followed by 12 months at 4p/kWh. None of the other tariff structures I've seen (Flux, Cosy, etc) have ever looked like being competitive with IOG for me.
130m2 4 bed detached house in West Yorkshire
10kW Mitsubishi Ecodan R290 Heat Pump - Installed June 2025
6.3kWp PV, 5kW Sunsynk Inverter, 3 x 5.3kWh Sunsynk Batteries
MyEnergi Zappi Charger for 1 EV (Ioniq5) and 1 PHEV (Outlander)
User of Havenwise (Full control Jun-Dec 2025, DHW only from early Dec)
Subscriber to MelPump App data via CN105 Dongle Kit
-
Sunsynk Whole House Backup Issue
7 months ago
Currently viewing this topic 1 guest.
- 27 Forums
- 2,741 Topics
- 64.3 K Posts
- 1,153 Online
- 7,145 Members
Join Us!
Installer Finder
Degrees of Separation
Latest Posts
-
RE: Indevolt Batteries UK Support & Info Thread
@jamespa Hello, to guarantee 100% compliance across all...
By Indevolt Tech , 4 minutes ago
-
RE: Do I need to change the control unit when replacing my Ecodan Air Source Heat Pump
Kind of you, @calumm, but it was @f1p who did the heavy...
By Majordennisbloodnok , 2 hours ago
-
The "thermal comfort" we feel is a mix of air temperatu...
By bobflux , 2 hours ago
-
RE: Electricity price predictions
2. As EV ownershp increases it'll certainly increase de...
By EtchedPixels , 12 hours ago
-
I meant to say I cannot register my kit at Energyplus… ...
By Batpred , 13 hours ago
-
RE: PV and battery long payback - sense check query
So if it helps I was recently quoted about 8 grand for ...
By EtchedPixels , 2 days ago
-
RE: HomeTherma Is Live: A New Home-Energy Platform Built Around the Homeowner
Signed up!
By bobflux , 2 days ago
-
RE: Has anyone seen this problem before? Huge anticycling times
Oh dear. Glad it was replaced. I have been mighty imp...
By JamesPa , 3 days ago
-
RE: Can I start an argument about buffer tanks please? 🙂
Dont, just adjust the LSVs to get different temperature...
By JamesPa , 3 days ago
-
RE: Heat pump running costs – what has actually worked for you?
I installed the air source heat pump in January 2026, i...
By bobflux , 4 days ago
-
RE: Grant Aerona Air to Water R290 6.5 kW - Quiet Mark and Silent Running
Thats all interesting. DHW on my Vailant seems to respe...
By JamesPa , 4 days ago




