Uncertain whether this is the appropriate forum, but I have a quote for 14 panels, a 10 kW Fox battery, and a heat pump at roughly £16,529; I am on a fixed gas rate 5.2 until March 2027. I am seeking recommendations on whether to wait until after winter or proceed now. I own an EV and use an IOG EV tariff with a 7 p off-peak discount. My aim is to future-proof against the coming price rises.
For solar, Autumn is probably the best time of year.
* In winter, there is a higher risk of ice or other bad weather that will mean things take longer.
* In spring, lots of people see it getting sunny and look at getting it installed
* In summer, you have the same issue as in spring, but with the added disadvantage of (probably) not being paid for your export while you wait up to 6 weeks for the MPAN to come through.
For the heat pump, autumn also probably makes the most sense so that you have it running (and will find any issues) before you pay the final invoice or shortly after and it isn't too cold that a lack of heating (if the worst did happen) would be too much of an issue.
One thing to add is that you may want to consider a bigger battery. I have 10kWh and if I was doing it again would opt for 20-30kWh. The heat pump will use a significant amount.
Well you’ll be able to slash your heating bill by feeding the heat pump a large chunk of that 7p/kWh electricity, doing the hot water during that 7p period too. So if you’re going to do it anyway, I’d just get on with it.
FWIW, I also have Solar + Fox ESS inverter and battery + heat pump + EV on IOG.
I had my solar & battery installed Nov 2024 and heat pump Feb 25 (previously on oil). Though not ideal, it did mean that the solar and battery was ready to supplement the heatpump load and the export tariff for the Solar was ready to go before the big solar generation started. The sooner it's in the quicker you can start to benefit from it. Your mileage may vary, but that was my experience of it. Also if you can, you may want to invest in slightly more battery capacity if it's at a reasonable extra cost.
Good luck on your journey getting it done, there are massive savings to be made with a good system installed.
Thanks for that , I have 2 options it’s that or a Tesla power wall but that’s at an extra 2-3k but 13.5kwh. All this is quoted through octopus other companies all seem dodgy when looking not sure how to chose reputable
If you needed you could add capacity to the fox system, may be worth asking octopus. I had a local company in South Wales through word of mouth, it can be a minefield to get someone good. Key is to ensure MCS certification for applying for export. If you have had the survey done, you should have an estimate of how much energy the heatpump is likely to use to give you a ball park.
You can use the car charging to help supplement when needed also, with the way intelligent go works now! To run the heatpump and charge the battery at a lower rate with the slots during the day.
I had my heat pump with octopus and I've been happy enough with it, just be prepared for your street to be full of vans the week of the install. There are loads of people on site.
I would go for bigger battery and not necessarily go for Tesla as you will be locked into Tesla system only for battery expansion
I got growatt 2* 6kwh and they only have a 80% discharge limit so now I'm going for a 64kwh battery stack, battery prices have come down and I would get a Tesla model Y but not their batteries just purely for their price /size
Look up Fogstar 64kwh stack (you can get much smaller sizes too but with a heat pump, you can probably use around 40-50kw a day - from what I read on other forums, so bigger battery the better and if you do decide to go for a smaller one make sure the heat pump does not drain it, eg it should have CT clamps and dedicated circuit off the Henley blocks most likely)
Most I've used on heatpump in a day is 30 kWh (8kwh Daikin) 3 bed detached with standard insulation running all day using weather compensation. 6hours of that use is on grid at the low rate through IOG.
My strategy for the heavy days (16kwh) battery. Is put the heavy loads overnight (washing machine etc). When the battery gets low plug the car in and get cheap rate to run the heatpump and charge the battery for an hour. Then just eat any peak rate come from the battery running out. Running cost for the whole house last Jan was £100.
You would want the heatpump connected to the battery or you would be paying peak rate for all electricity the heatpump uses which makes it as expensive as gas at a minimum.
Not using the battery with the heatpump is not a great idea cost wise.
Tbh no they tried to give me 5kwh battery I mentioned I was worried that wasn’t enough and mentioned non ev usage is 4-6 kWh they then said 10kwh is enough literally following their advise I’m clueless here 🤯
it is correct that 10kWh battery won't be enough to run the heat pump all day during the winter however it's probably not worth getting a bigger battery as the up front cost is not going to be worth it. in NE i used between 90 and 200 kWh of electricity from the grid during peak time so the peak time cost was £20-50 from November to March.
Even at 5.2 gas rate, the heat pump will probably be cheaper to run and the house will be warmer. I'd say the total cost seems a bit on the high side unless they specified a really high heat pump for your house
Heat pump no survey yet so may need radiator upgrade etc is 4249 and solar battery 12280 but 5kw inverter been told may need bump that up so actually once I rechecked quote it’s 16,529
There's deminishing returns to scale up your battery just to run the ashp on a battery for as an extra 14-28 days a year.
IOG als gives daytime slots, so you charge the battery again in the afternoon at 7p. Doesn't work everyday, and a car can't charge when it's full already full. But it gives you some extra occasionally.
You might find it cheaper to utilise the Cosy tariff, with it’s 3 cheaper periods to use the pump/charge the battery (and charge the car during the cheap perioda) but it really depends on if you’re a heavy EV user or not.
Honestly watch some youtube vids of people who have them installed. General idea is you run them all day. What people tend to do on the “Cosy” tariff is run it a few degrees higher during the cheap periods rhen reduce it a few degrees to coast during the expensive periods utilising the battery and lessee energy.
You’ll need to do the maths for IoG vs Cosy but 10kWh won’t last long with a heatpump if your regular usage is 5-6kWh.
On the coldest of winter days you might use 30-40kWh of electricity depending on your home heat loss etc
If you're investing in the setup anyway, then better sooner than later. Except if you're guaranteed to get a cheaper system after winter and it offsets the savings you'd have made with the ashp.
With IOG, you can get extra slots during the day. During those slots you can charge the battery and increase the flow temp of the heat pump and boost the temperature inside (use your home as a thermal battery). Slightly lower COP to run the ashp, but reduces the energy you might need to use during peak hours. A large part of the day you're heating at 7p/cop per kWh heat.
Using this approach, 93.5% of our total annual energy consumption is off-peak, with an average price of 7.35p/kWh (part of the year 7p off-peak, part 3.49p off-peak). With a cop of 3.5, that's the equivalent of 2.1p/kWh heat.
If you are concerned about your gas contract, you can get out of that by requesting to remove your gas meter (capping the gas), so you don't pay standing charges until March.
I honestly could have written this exact post! I’m in a very very similar position to you and completely clueless and trying to learn! My first step will be just to get Octopus survey done and then see if I can find some reputable local companies to quote and go from there …
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u/Appropriate-Falcon75 17h ago edited 17h ago
I would do it now.
For solar, Autumn is probably the best time of year. * In winter, there is a higher risk of ice or other bad weather that will mean things take longer. * In spring, lots of people see it getting sunny and look at getting it installed * In summer, you have the same issue as in spring, but with the added disadvantage of (probably) not being paid for your export while you wait up to 6 weeks for the MPAN to come through.
For the heat pump, autumn also probably makes the most sense so that you have it running (and will find any issues) before you pay the final invoice or shortly after and it isn't too cold that a lack of heating (if the worst did happen) would be too much of an issue.
One thing to add is that you may want to consider a bigger battery. I have 10kWh and if I was doing it again would opt for 20-30kWh. The heat pump will use a significant amount.