Help with changes to current set up

NedS

https://forums.moneysavingexpert.com/discussion/comment/82124089#Comment_82124089

Staggering the loads is your best option. Things like heating hot water will presumably not take the full cheap rate period and can be staggered with anything else likewise, and as you say the EV charging can load balance as a last resort.

Also, I have an option to turn my heat pump down to half power mode (you may have similar, or a quiet or ECO mode that reduces power) so it takes a little while longer to run the DHW cycle but isn't running flat out. My 12kW heat pump ramps up from around 1.5-3.0kW over the course of the run. When running flat out during an octopus free electricity hour, it can peak at ~4.8kW

Final option - sell the hot tub!

bintyandthebeast

I really don't want to pull 100amps+ and keep fingers crossed so will stagger what I can. Most nights the car is done after a couple of hours and hot water can get moved by 2/3 hours which should sort it.

We do have an eco mode on our Panasonic heat pump and I also think it's been massively overspecced so will see how first winter goes.

I appreciate I should probably look at a 3-phase supply but trying to avoid the expense. It would more than cancel out the savings I'm making when installing new batteries & larger inverter to charge them a waste of time

NedS

@bintyandthebeast wrote:

We do have an eco mode on our Panasonic heat pump and I also think it's been massively overspecced so will see how first winter goes.

Same here, we have a 12kW heat pump, when a 5-7kW unit probably would have done the job. Running in Eco mode should hopefully reduce power draw at the expense of taking a little longer to heat the tank. As the Eco name suggests, it's also more economical as compressors are more efficient operating in the 40-75% range than when running flat out, and Eco mode most likely restricts compressor frequency which reduces power use and improves efficiency.

bintyandthebeast

An update: it's been 8 weeks and still waiting on DNO approval. Installer keep chasing and they say they have what they need.

We've had a few days of frost and high winds so have had some unexpectedly high electricity consumption. At the moment I can't confirm fully whether it's down to the hot tub (which costs a fortune to run through winter, despite it being one of the cheapest to run!) or home heating. I didn't click when signing off on our heat pump that the 2x large fan coils would be running most of the day, so expect on the colder days we can use 15-25kwh on top of what the heat pump uses.

Despite currently having a 10kwh battery (9 kWh useable) and overnight cheap rate for 5 hours on a deprecated tariff (5.23p overnight / 27.3p peak - expiry 31/3/27) we can burn £15+ per day (~50kwh at peak rate) on colder days. As we live semi-rurally in Scotland I reckon this will be the norm through the winter months, if not worse, so we've changed our install to 64.4kwh battery assuming we get the 10kw inverter signed off. I plan on moving to EDF for their 7 hour cheap rate to spread overnight load for our fuse rather than have car / tub / etc running simultaneously. Summer months I think we should last week's without paying for energy / export plenty.

All in I expect <5 year payback as we are high users.

I'll update when I get DNO feedback. Installer currently has batteries and inverters so hopeful for a quick install once confirmed.

sabretoothtigger

Nice rates but thats a giant battery. You've checked for lost heat in obvious places that could be sealed better etc. I presume so.

I have 40kwh battery but its attached to a car lol it can power the house, sadly this is legacy system and they are behind providing this solution to people which seems incorrect when its an obvious overlap in utility.

bintyandthebeast

We have a modern (2012 built) house and it's we'll put together. Solar glass at rear, 500mm loft insulation, etc, so not much more to be done to minimise heat loss. The house is 320m2 and we also now have a separate a/c unit for my home office (fancy shed) so plenty power needed through the day.

I totally agree, I'd like to have had a car to plug in and use for house load, particularly as I work from home most days. We bought a Skoda Enyaq this year and our 3 year old Volvo (diesel) has barely moved off the drive since. We got £12.5k off list so I'm not too sad about about not having V2L available, the cost for a separate install will cover this and mean it can run 24/7.

My only hope is power companies maintain the overnight cheap rates for 5+ years to cover the cost. I'm not 100% hopeful as expect the shift to EV / battery will continue to pick up and the differential between day and night rates will reduce.

QrizB

My only hope is power companies maintain the overnight cheap rates for 5+ years to cover the cost. I'm not 100% hopeful as expect the shift to EV / battery will continue to pick up and the differential between day and night rates will reduce.

There are >10GWh of commercial battery capacity installed, and more under construction, that's relying on there being significant swings between the cheapest half-hour of the day and the most expensive.

It might not be as regular as "overnight cheap, early evening expensive" but there will still be daily highs and lows. I'm fairly confident that home batteries will continue to allow you to save money through power arbitrage for the foreseeable future.

Heedtheadvice

I have not been breading through all the thread so apologies if these have been discussed or you have addressed them already.

As mentioned by tigger heat loss might still be an issue that you could prove.

Your property should be well insulated but is quite big so possibly check that loft insulation is maximised I.e. 150mm minimum these days. If your floor is above a void is that insulated too? Similar considerations for your home office.

The hot tub is an expensive to run luxury, as you will know, but can you keep the heat down a touch and provide more insulation when not in use? Is it heated via heat pump or more historical means?

and how about a Heat recovery system?

Or looking into whether your heat pump can be weather protected, protect a bit from the cold winds or surround to get some solar gain?

Probsbly some of these are non starters but some or all of these could reduce your consumption and hence running cost but maintain lifestyle

bintyandthebeast

https://forums.moneysavingexpert.com/discussion/comment/82183452#Comment_82183452

Fingers crossed that's the case. Will be a costly mistake for me otherwise!

bintyandthebeast

We're well covered. Good loft & wall insulation, underfloor heating,

Hot tub is on an old fashioned heater so will be significantly cheaper to run. The cost of a heat pump for the tub will not recoup itself when we get the new battery installed.

Heat recovery is out as we have 9 zone ducted heat and cool upstairs so attic space is virtually non existent now. Again, the cost being driven down by the new battery will mean that would be costly and we would not recoup the outlay.

It feels strange to hope for long term high energy prices and an overnight cheap rate but that's where I am!