Electricity costs

I know this has probably been asked innumerable times before but I would appreciate any comments on my household electricity bills. I have monitored our bills for a few years now so have an idea of our metered consumption. It has, for a long time, seemed to me to be quite high but electricity is our only energy source so powers everything (except gas hob which is propane) – heating, lighting, cooking, leisure, etc

Our supplier, Octopus, gives an estimated consumption for the year, presumably based on previous bills, with each bill. This agrees quite closely with our historic consumption for the last few years. this would give an annual cost 03 £4515 at current rates, equating to £376 monthly. Our direct debit is for £525; set by Octopus but they do adjust this occasionally if we are in credit. I do need to contact them about the direct debit being so high.

The house is a renovated stone-built croft cottage in Aberdeenshire. Renovated in 2007 to then-current insulation standards. Added extension in 2014 as self-contained flat. The main house has a ground source heat pump and underfloor heating downstairs, radiators to upstairs bedrooms. The flat has an air-source heat pump. Floor areas: House downstairs – 95m2, house upstairs – 32m2, flat 46m2. We have a 4kW solar array on the barn roof.

Another question – who would be the best person to inspect the house and provide advice on consumption/electricity usage? Local electrician or specialist engineer?

If any knowledgable forumite would care to comment, thanks.

You should be able to adjust your DD via your account. I can.

Of course octopus want you to pay more as its better for them in their account than yours. Lower it to what you think you should pay not what they think. Or if you have the funds for big winter bills get onto variable DD and you only pay for what you use. This will give highs and lows over the year rather than a equal amount ea month. It’s your money that want  in their account don’t be fooled that they are doing the best for you.

Good god man, you’re paying 4x what I do, I thought that might make sense for electric heating until I got to the bit about gshp (efficient for electric) and a solar array! And I’m running an electric car. Something ain’t right.

Could well be worth having someone in, something seems amiss. But I’m not sure who… fingers crossed for the geniuses of stw to emerge.

That seems punchy.

You can certainly set your octopus DD yourself to whatever you deem appropriate. If you think it’s £380 then you should be able to set it there.

Have you/can you optimise tariff? I assume, given you have GSHP & solar that you will have done the basic energy efficiency stuff on the rest of the house, if so I’d start hunting for things that are drawing more than they should be at that rate. We’re on £40/month for electricity and gas with an EV (with a similar size solar & batteries).

That’s huge. I’m paying about £220 for a month in Dec/Jan (ok so it’s mild down here) and about £100 in summer for both gas and electricity (including car), and I don’t have solar.

I would start by looking at your heat pump’s efficiency coefficient. Many heat pumps are badly sized, installed or configured. Your output temperature needs to be as low as possible, otherwise it starts to get quite pricey. And to heat your home with low temperatures you need a low output temperature – 50 or even 40C – and for that to work you need big radiators. To heat your hot water though you will need more than 50C so you need to configure it to heat the hot water differently and you need a different type of tank (if you have one).

So yeah you need a heating engineer to look at it. Then there are a whole host of efficiency improvements that can be made to a house besides simply fitting insulation to the walls and roof.

Our house area is around the same as your combined area and we have Oil and Electricity with a solar array and batteries.  Our ~6000kWh a year of electricity costs around £200.  We use around 1500l of oil which is 9kWh/L, but at 75-80% efficiency (30y old boiler) so ~10000kWh of thermal.  Assuming your GSHP was running properly (At COP of 3:1) and the house is even moderately insulated, you’d be looking at needing around an additional 3500-4000kWh of power for heating and HW. That’s around £1000-£1200.

Assuming you have no batteries and the solar array hasn’t been cleaned in a while, and that you’re not intentionally maximising its use, I’d say you might only be getting around 2500kWh/Y out of it and little income from export from it.  Given your latitude, the multiple properties, your total energy requirements might be around 16000-20000kWh per year with 10-12k kWh being thermal and that coming from HP with a nominal COP of 3:1 , That would give you an electricity draw of maybe 10000-14000kWh/y of which maybe 2500kWh are from the solar.  That would place your bill at around £3200 a year (inc Standing Charge) ata rate of 0.25p/kWh.

It’d be better with kWh figures rather than the cost as it’ll be easier for others to relate.

It doesn’t sound too bad, you’re heating a large (nearly 200m2) stone building in Aberdeenshire using a heat pump, which whilst they’re more environmentally friendly than running gas central heating they’re also more expensive.

Solar panels will be great during the summer months but they’re not going to provide much power over winter, when you really need them. My 4kW install provides as little as 50kWh a month during winter.

Thanks guys, that’s really useful. I guess I need to contact a heating engineer.
As well as being ASHP installers, the company who installed ours are refrigeration engineers, and will be carrying out its annual service in December. So perhaps they would be good to ask.

What tariff are you on?

which whilst they’re more environmentally friendly than running gas central heating they’re also more expensive

That part is debatable. They *shouldn’t* be more expensive if done right, but it’s not always possible to do it well enough.

as above,  what tariff? if you’re on a fixed tariff you’re missing a trick or 5

That part is debatable. They *shouldn’t* be more expensive if done right, but it’s not always possible to do it well enough.

kWh per kWh gas is a lot cheaper than electricity, until it isn’t then it’s going to be cheaper using gas central heating. The cross over point is getting closer though, especially with the new tariffs available for heat pump users.

Heat pump installations in existing housing stock usually coincide with a large upgrade in insulation, you could carry out that same insulation upgrade without changing from gas central heating and see a vast improvement in cost and comfort (obviously if you’re remote and using oil, lpg etc then that’s different)

I would like one myself but the cost to change (and ripping out and scrapping a good boiler and most likely radiators) doesn’t sit well. The noise is also a concern, it’s very quiet where I live and when I’m out in the evening over winter you can hear the hum from quite a distance.

kWh per kWh gas is a lot cheaper than electricity, until it isn’t then it’s going to be cheaper using gas central heating.

Yeah it’s about 3x the price for me, which means I would need a heat pump to run at a COP of 3:1 or better, in other words it can emit 3 times more heat energy than the electrical energy it consumes. The hotter you have the output temperature the worse the COP, but also the colder the outside air or ground. To warm your house with cooler radiators you need good insulation, thick pipes and big radiators. As you say, these things also help gas heating be more efficient as well.

There are a few other things though – given we get cheaper electricity overnight we can use that to put some heat into the house and then we would need less in the morning; we can also use that to heat our hot water overnight. If we had wet underfloor heating, we would run that overnight at cheap rate to get the thermal mass up to temp.

There are of course many other things you can do to your house that don’t cost much but can have a big payback. Heavy curtains is one, or two sets of curtains mounted so you can have the thick ones closed at night but a thin set of muslin curtains drawn during the day – still lets light in but keeps a surprising amount of heat in. We also have a thick curtain over the front door on a portiere rack. In cold weather we put up a temporary pole and some curtains up at the bottom of the stairs which keeps the downstairs absolutely toasty. This is probably the most cost effective thing you can do.

Our boiler is ancient and could fail at any time, I can’t really afford a heat pump right now but I really don’t want to pay for another gas boiler. I’ve been fitting big rads gradually, this will be complete this autumn. Even they pay for themselves tbh as they are only cheap rads.

I’d not be able to sleep at night paying that much

£40 a month here. 2 adults in a 4 bed house with 8 solar panels on the roof

kWh per kWh gas is a lot cheaper than electricity

True but remember that a good proportion of that difference is tax. Seems wrong that there is more tax (both in absolute and percentage terms) on the fuel with lower carbon emissions.

And a few of the energy suppliers are now advocating a change there.

True but remember that a good proportion of that difference is tax. Seems wrong that there is more tax (both in absolute and percentage terms) on the fuel with lower carbon emissions.

And a few of the energy suppliers are now advocating a change there.

Yup, but changing that is going to punish the poor.

@J273  @alan1977

Tariff is Flexible Octopus:
Unit rate (Day)   29.41p per kW/h
Unit rate (Night)   13.02p per kW/h
Standing charge   57.31p/day

The heat pumps are run continuously, relying on individual room thermostats to control demand. We were advised this was the way to run heat pumps with U/F heating. This avoids having to heat the concrete floor from a low temperature twice a day and should maintain a more even temperature.

@mikejd

Flexible will cost you a fortune.  You should switch to their tracker tariff.  You will probably half your bill.

Octopus Tracker needs a smart meter, which we don’t have. I should probably contact Octopus and check alternative tariffs. I’m due to send the monthly meter reading on 23rd so I’ll wait until after that.

Ayrshire. Stone house – no cavity walls, insulation galore in the loft.

Me, the Mrs, two students and the youngest (still at school)

Computers galore, hairdriers on full blast, lights that never seem to be turned off – such is life – I resort to having a LabX on my feet in winter to keep some semblance of warmth. Being Scotland, Winter is pretty much 12months a year.

Was paying 370 a month or so with EDF for the combined tariffs – they would much rather I banked with them, rather than me possibly owe them money at month end. At one point they were asking over a grand a month for power/gas because they didn’t have enough fingers to do the math.

Your costs are not crazy compared to mine, I no longer trust energy suppliers but haven’t found a viable means of making them into something I could use to heat the house. Pity

Agile tariff here.

No heat pump.

No solar.

Battery car.

If you choose agile become competent in varying your demand. At the moment I’m heating my house for no reason other than negative pricing.

On agile I’d be manually controlling my heat pump. Turning it off and on when the prices drop and the prices increase. The heat loss would be minimal, I think?

Reduce the system temp by a few degrees?

Last April I used 480kwh of electricity and it only cost me £5 + standing charge of £0.50 a day. Max out when the power is cheap, suffer a little when the power is expensive.

Agile tariff is great. If you are willing to adapt to the daily changes.

needs a smart meter, which we don’t have

Any particular reason? Getting one would open up a host of other tarrifs that could be cheaper for your usage.

you definitely want to get the ball rolling on a smart meter install, there’s a very long lead time in certain areas of the country (mine)

@flicker

Yup, but changing that is going to punish the poor.

Given the way social housing providers are installing / planning to install heat pumps, possibly quite the reverse.