Where do I start - solar or heat pump?

MallyGirl

After an eye wateringly expensive energy day on Wednesday, when it got very cold, I am starting to look at options to invest now - while working - to recoup the benefits once retired.
The house is largeish, Victorian so no cavity walls to fill, single glazed sashes (with secondary glazing on bedrooms), 10' ceilings. The conservatory/garden room which we spend most time in has wet UFH. We long ago turned off the electric UFH in the bathroom. Despite not heating the rooms that we don't use regularly our usage is very high. Gas 25,000 kWh, elec 7,000 kWh so roughly £2k each per year. We have a fairly new (2 yrs old) boiler and a megaflow hot water tank.
Our electric use is higher than it would be in retirement as I wfh and the heating is all electric in my office at the bottom of the garden. The gas might be higher in retirement as we currently only heat the main body of the house in the evenings. When OH wfh his office is on a separate central heating circuit so we just heat those radiators.
We could look at solar panels as the roof is quite big (30' wide maybe) with just a couple of Veluxes - it faces WSW. OH's office is a long room in the roofspace if that makes a difference - very cold in winter and hot in summer despite insulation.
We could look at heat pumps and batteries.
I have no idea where to start - do we look for local companies that do both and see what they say. I welcome all suggestions for the 'for dummies' level reading to get to grips with what we could do.

paul991

as your home all day solar Pv would be a good start but internal insulation as much as you can. underfloor ect

Screwdriva

Given that you some single glazing, newish boiler and no wall insulation, my suggestion would be to skip the Air Source Heat Pump for now. (Ground Source may work more consistently for you but you'll need roughly 3X the area to heat in sun soaked land if you want the more affordable "slinky" version). 

Solar PV would be a more natural first step and deliver a more predictable outcome and return on investment. Given your high consumption and the need for electric heating in a room, a battery would also make sense. I'd recommend getting PV installers to deliver a no cost roof survey and quote. I expect a large roof + 13.5 kW battery would cost you in the region of £13-15K installed, depending on complexity of the job and # of panels. 

Lastly, have you tried turning down your boiler's flow temperature to allow it to condense? (this is not the thermostat but the control on the boiler itself).  

Meatballs

I would look at solar PV as big array as you can get and consider switching the office to a minisplit Aircon unit (assuming you currently use resistive heating).

thevilla

Insulation Insulation Insulation.  Then solar imop.

Exiled_Tyke

thevilla said:

Insulation Insulation Insulation.  Then solar imop.

Couldn't agree more. Insulate everything that can be insulated.  Get all the windows secondary glazed. (if you can afford it replace them with double-glazed). When we've upgraded a room we've added internal wall insulation each time. Underfloor insulation has also made a big difference.  

Only then is it worth looking at PV or ASHPs. 

You won't get the government grant on an ASHP unless the house is well insulated.  

Meatballs

Exiled_Tyke said:

thevilla said:

Insulation Insulation Insulation.  Then solar imop.

Couldn't agree more. Insulate everything that can be insulated.  Get all the windows secondary glazed. (if you can afford it replace them with double-glazed). When we've upgraded a room we've added internal wall insulation each time. Underfloor insulation has also made a big difference.  

Only then is it worth looking at PV or ASHPs. 

You won't get the government grant on an ASHP unless the house is well insulated.  

You don't need "well insulated" for the grant, just no EPC recommendation for cavity or loft insulation.

PV can often be done without any disruptive works to the house if all the easy insulation jobs have been done (cavity/loft). Going above these can be disruptive and/or costly and may be better achieved as you redecorate rooms rather than in one go.

If the office is direct electric heating, then Aircon unit there would reduce energy usage significantly and be fairly quick and non disruptive.

Yes ideally insulation first but it's not always that practical to improve above the basics as it often involves ripping up floors and walls or is very costly for new windows with long payback. I would definitely look at insulating the main house before putting in a full ASHP for that, but if they aren't ready for that I think they can achieve savings quickly and easily without doing it.

Reed_Richards

At current fuel prices the running costs for a gas boiler should be similar to those for an ASHP.  A ground source heat pump should do a bit better but you might never recoup the extra cost of installing one in running cost savings.

MallyGirl

Thanks all. 

We have loft insulation but the walls have no cavities to fill. The internals are quite twiddly- picture rails, ornate skirting, lots of coving, fireplaces, bookcases built into every alcove - so insulating inside would be difficult and destructive. We will need to strike a balance there. We did put in the best underlay we could get when we carpeted a room with just floorboards previously. Hall and upstairs are all still floorboards or tiles. 

We will look at secondary glazing for the windows that don't have it - when we last replaced sashes with double glazed sashes it was a grand a panel 20 years ago and we have 2 three panel bays. They have to stay as sashes as it is in a conservation area.
I will look at an air con unit for the garden office - it is well insulated as we converted it to code 12/13 years ago but the only heating is underfloor electric cables on a backing that is installed under laminate. I am having to use an oil filled radiator as well during this cold snap as it was only 6 degrees in there on Monday morning after being off for the weekend! It also can get quite hot in summer so the air con would be nice then too.
Lots of avenues to explore.

Screwdriva

You can always go with external wall insulation where possible and where not, internal insulation boards work well. Definitely not a small project but not ultra disruptive either.

Without this and the additional window glazing, a heat pump will struggle to warm the property without massive heat emitters (radiators).  

All that said, Solar PV is not dependent on any of this. If you had £6K to spend, I'd spend it on PV first purely for the faster return on investment and use the annual savings to fund my insulation project. 

Exiled_Tyke

Octopus told me that they won't install an ASHP unless there is 300mm of roof insulation. (That's what I meant by 'well insulated')   It's worth checking how much is up there as the suggested depth seems to have gone up over recent years.