Solar panels, EVs with a slight advantage/disadvantage
Discussion
Wanted some people's thoughts on this, so I'll paint you a picture of my scenario.
Recently purchased a house, currently have 1 ev, will likely get another or at least a phev with a 40 mile EV only range for the Mrs.
From previous calculations Solar hasn't been worth it from a financial stand point in recent times.
However, the house I have purchased, has an ancient central heating system (warm air heating).
This needs to be replaced at a cost of circa £8-10k with a boiler system and all the relevant radiators and piping.
In addition, I'm budgeting a further £3-4k to rewire and replace existing stuff, as it's truly ancient.
I'm thinking, instead of gas central heating, would it be worthwhile getting solar panels with a battery and using a combination of electric radiator/underfloor heating.
And ofcourse will utilize some of the solar power to charge the cars.
The usual debate of recouping cost is less applicable here as I need to spend £8k anyway. But solar instead of gas central heating?
The house is a medium size 3 bedroom semi detached (East facing).
Anyone with some expertise or experience on the matter want to share their thoughts?
Many thanks in advance
Recently purchased a house, currently have 1 ev, will likely get another or at least a phev with a 40 mile EV only range for the Mrs.
From previous calculations Solar hasn't been worth it from a financial stand point in recent times.
However, the house I have purchased, has an ancient central heating system (warm air heating).
This needs to be replaced at a cost of circa £8-10k with a boiler system and all the relevant radiators and piping.
In addition, I'm budgeting a further £3-4k to rewire and replace existing stuff, as it's truly ancient.
I'm thinking, instead of gas central heating, would it be worthwhile getting solar panels with a battery and using a combination of electric radiator/underfloor heating.
And ofcourse will utilize some of the solar power to charge the cars.
The usual debate of recouping cost is less applicable here as I need to spend £8k anyway. But solar instead of gas central heating?
The house is a medium size 3 bedroom semi detached (East facing).
Anyone with some expertise or experience on the matter want to share their thoughts?
Many thanks in advance
Plan on how you are going to heat the house in winter if you aren't going to burn gas. Bare in mind electricity prices are going to 30p+ per kWh come April.
Any solar PV setup in the UK will generate next to nothing during winter. This is our solar PV setup and how little it generates during November to February.
We have an EV, solar PV and home battery. We are also lucky enough to have the land needed for ground sourced heat pumps, but we are sticking with gas for our planned house renovations later this year.
For heat generation you simply cannot beat burning stuff.
Any solar PV setup in the UK will generate next to nothing during winter. This is our solar PV setup and how little it generates during November to February.
We have an EV, solar PV and home battery. We are also lucky enough to have the land needed for ground sourced heat pumps, but we are sticking with gas for our planned house renovations later this year.
For heat generation you simply cannot beat burning stuff.
In the UK, while solar can provide a useful amount of electricity the shortness or our days in winter almost certainly precludes heating a house with the output. It's worth having but I don't think you'll achieve your ambition.
If you're having to rip out and replace the heating in it's entirety, it would certainly be sensible to consider a heat pump replacement - probably air source from what you've described. Bin the gas cooker/hob and you can have the gas supply capped off along with the standing charge for supply etc.
(There's a lot of nonsense spouted about heat pumps from people who seem scared of anything new, rather like EV's, so try not to be put off by them. They require careful measuring to ensure the installation matches your reality, but are entirely practical)
If you're having to rip out and replace the heating in it's entirety, it would certainly be sensible to consider a heat pump replacement - probably air source from what you've described. Bin the gas cooker/hob and you can have the gas supply capped off along with the standing charge for supply etc.
(There's a lot of nonsense spouted about heat pumps from people who seem scared of anything new, rather like EV's, so try not to be put off by them. They require careful measuring to ensure the installation matches your reality, but are entirely practical)
Knock_knock said:
(There's a lot of nonsense spouted about heat pumps from people who seem scared of anything new, rather like EV's, so try not to be put off by them. They require careful measuring to ensure the installation matches your reality, but are entirely practical)
How much is a heatpump going to cost to run with 30p+ per kWh of electricity coming everyones way?The best examples show parity with gas for cost, and that's using cheap electricity traffis which are pretty much all gone now.
I would love to get the maths to balance to justify a heat pump for heating the house versus gas but the numbers just don't work.
Spending money on better insulation which seems to be a mandatory prerequisite to a heat pump install though makes perfect sense.
Really insightful reply, appreciate it.
Perhaps only worth it if I can put up with higher bills November - February.
I know the govt wants us to come away from gas boilers, but there just seems to be no viable alternative. I'm not sold on heat pumps.
Seems I have to spend money on a system which will be discouraged in the near future (our faithful friend, fossil fuel)
Perhaps only worth it if I can put up with higher bills November - February.
I know the govt wants us to come away from gas boilers, but there just seems to be no viable alternative. I'm not sold on heat pumps.
Seems I have to spend money on a system which will be discouraged in the near future (our faithful friend, fossil fuel)
gangzoom said:
Knock_knock said:
(There's a lot of nonsense spouted about heat pumps from people who seem scared of anything new, rather like EV's, so try not to be put off by them. They require careful measuring to ensure the installation matches your reality, but are entirely practical)
How much is a heatpump going to cost to run with 30p+ per kWh of electricity coming everyones way?The best examples show parity with gas for cost, and that's using cheap electricity traffis which are pretty much all gone now.
Scrump said:
When you need the heating the solar panels will not be be generating very much. (Winter)
When the solar panels are generating a decent amount you will not need the heating. (Summer)
A battery is not going to solve this.
You can also charge the battery overnight on cheap rate. I get 8kWh of power every day at 5p per kW, and if the sun does shine during the winter, I can top up the battery or charge the EVWhen the solar panels are generating a decent amount you will not need the heating. (Summer)
A battery is not going to solve this.
Knock_knock said:
(There's a lot of nonsense spouted about heat pumps from people who seem scared of anything new, rather like EV's, so try not to be put off by them. They require careful measuring to ensure the installation matches your reality, but are entirely practical)
Finally, someone else who understands heat pump.I've done around 500 underfloor heating heat pump installs here in NZ, and yes winter daytime temperatures are warmer - but there is no reason not to consider them in the UK.
Batteries are the bit that don't work at the moment
.
Real numbers from my 4kW array in the south of England - yesterday, decent winter’s day with sunshine - 3.34 kW.
Battery or no, that doesn’t even cover the daily consumption of the house, let alone heating. Per the graph above, panels deliver in the summer, and generate very little in the winter.
Heat pumps are fine IF you have a suitable house. The science is simple - they are more efficient at lower outflow temperatures. If you try and drive one like a conventional boiler with a outflow of 70C, your bills will be astronomical. If you can run one with an outflow of 24C - then you will reap sizeable efficiency. So loads of UFH, big radiators, it works. Bolting onto an existing gas CH will be a disaster.
On top of that, there is the challenge that electricity is about 3x as expensive per kW as gas. So nearly all of your theoretical heap pump efficiency is consumed in pricing. This may change.
Battery or no, that doesn’t even cover the daily consumption of the house, let alone heating. Per the graph above, panels deliver in the summer, and generate very little in the winter.
Heat pumps are fine IF you have a suitable house. The science is simple - they are more efficient at lower outflow temperatures. If you try and drive one like a conventional boiler with a outflow of 70C, your bills will be astronomical. If you can run one with an outflow of 24C - then you will reap sizeable efficiency. So loads of UFH, big radiators, it works. Bolting onto an existing gas CH will be a disaster.
On top of that, there is the challenge that electricity is about 3x as expensive per kW as gas. So nearly all of your theoretical heap pump efficiency is consumed in pricing. This may change.
I've only looked at them briefly so not speaking with any authority but as above it could be worth looking at heat pumps if you're planning on renovating the house anyhow, can put in underfloor heating and if the house itself will be very efficient/ well insulated.
Certainly worth considering IMO as the direction of travel seems to be away from gas and towards electricity for heating. (and £5k grants at the minute IIRC)
They do seem like a minefield to the unitiated however, I'd certainly want to do plenty of homework and get recommendations on the installer - lots of types ranging from about 3kW to 15kW from just one manufacturer:
https://www.vaillant.co.uk/homeowners/products/ren...
Solar and batteries might also be worthwhile, we've the former and I'm looking (again) at the latter now that our energy prices look like they are going to double if not treble from April - tho' battery prices also seem to have gone up!
Certainly worth considering IMO as the direction of travel seems to be away from gas and towards electricity for heating. (and £5k grants at the minute IIRC)
They do seem like a minefield to the unitiated however, I'd certainly want to do plenty of homework and get recommendations on the installer - lots of types ranging from about 3kW to 15kW from just one manufacturer:
https://www.vaillant.co.uk/homeowners/products/ren...
Solar and batteries might also be worthwhile, we've the former and I'm looking (again) at the latter now that our energy prices look like they are going to double if not treble from April - tho' battery prices also seem to have gone up!
Edited by danp on Monday 17th January 12:13
My boss lives in a brand spanking new apartment with electric underfloor heating throughout.
At this time of year, if she uses the heating as she likes it consumes around £150-200 per month of electricity, this is in a well insulated 2 bedroom flat.
Electric heating is certainly not cheap, and you won't have much solar in the winter to boost it up.
At this time of year, if she uses the heating as she likes it consumes around £150-200 per month of electricity, this is in a well insulated 2 bedroom flat.
Electric heating is certainly not cheap, and you won't have much solar in the winter to boost it up.
Heat pumps are fine IF you have a suitable house. The science is simple - they are more efficient at lower outflow temperatures. If you try and drive one like a conventional boiler with a outflow of 70C, your bills will be astronomical. If you can run one with an outflow of 24C - then you will reap sizeable efficiency. So loads of UFH, big radiators, it works. Bolting onto an existing gas CH will be a disaster.
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Spot on!
To that I would add having to use an immersion heater for the hot water (to keep the ASHP in its most efficient range) which is fully viable but a larger tank may be prudent because of the slow recovery time.
The other issue is the total electrical load, not only at peak times but also what is presently off-peak. For example the overnight load could include an EV charging at 7 kW and the HW tank running at 6 kW plus the ASHP drawing 5 kW (if not more).
Others with more expertise can confirm but, aiui, standard domestic supplies are not designed for that sort of constant load, running for hours.
Lastly do you want all of your energy eggs in one basket? If the power goes out it's good to have gas for cooking at least.
Mikehig said:
Spot on!
To that I would add having to use an immersion heater for the hot water (to keep the ASHP in its most efficient range) which is fully viable but a larger tank may be prudent because of the slow recovery time.
The other issue is the total electrical load, not only at peak times but also what is presently off-peak. For example the overnight load could include an EV charging at 7 kW and the HW tank running at 6 kW plus the ASHP drawing 5 kW (if not more).
Others with more expertise can confirm but, aiui, standard domestic supplies are not designed for that sort of constant load, running for hours.
Lastly do you want all of your energy eggs in one basket? If the power goes out it's good to have gas for cooking at least.
The electrical load issue is also something I can talk about; we regularly charge an EV overnight, while the ASHP does it's thing, and often a dishwasher and/or washing machine and/or tumble dryer. Never been a problem at all.
The EV charger is on a separate way of the consumer unit, as is the ASHP. Also, our ASHP is the Ecodan 11.2kw version (their biggest single block) and it's maximum draw is 3.7kW - and I rarely see it draw more than 2kW.
So I don't think the load aspect is a problem at all.
We have a 35kw yes, 107 panel array, south facing and the whole of December generated the same as one summer day (300kwh)
That’s all you need to know!
Our heating in winter consists of 2 x gshp of 4kw each and 1 x ashp of 6kw.
We generally run them flat out for 5 hours each morning to charge the house up, so about 80kwh and then maybe one pump will run if there’s surplus solar.
It’s a large barn conversation with ok insulation.
That’s all you need to know!
Our heating in winter consists of 2 x gshp of 4kw each and 1 x ashp of 6kw.
We generally run them flat out for 5 hours each morning to charge the house up, so about 80kwh and then maybe one pump will run if there’s surplus solar.
It’s a large barn conversation with ok insulation.
Knock_knock said:
With our ASHP the immersion is only used during the legionella cycle once a week, and with a family of four we never run out of hot water just letting the ASHP deal with the water automatically. We have a c. 220 litre tank, which I think is pretty normal.
The electrical load issue is also something I can talk about; we regularly charge an EV overnight, while the ASHP does it's thing, and often a dishwasher and/or washing machine and/or tumble dryer. Never been a problem at all.
The EV charger is on a separate way of the consumer unit, as is the ASHP. Also, our ASHP is the Ecodan 11.2kw version (their biggest single block) and it's maximum draw is 3.7kW - and I rarely see it draw more than 2kW.
So I don't think the load aspect is a problem at all.
That's good real-world feedback, thank you.The electrical load issue is also something I can talk about; we regularly charge an EV overnight, while the ASHP does it's thing, and often a dishwasher and/or washing machine and/or tumble dryer. Never been a problem at all.
The EV charger is on a separate way of the consumer unit, as is the ASHP. Also, our ASHP is the Ecodan 11.2kw version (their biggest single block) and it's maximum draw is 3.7kW - and I rarely see it draw more than 2kW.
So I don't think the load aspect is a problem at all.
Those figures suggest your house is pretty well insulated because that ASHP output is quite a bit lower than most domestic boilers - unless you live somewhere warmer than the UK!
So I think my comments may only apply to large houses with relatively poor insulation (like my own).
Mikehig said:
That's good real-world feedback, thank you.
Those figures suggest your house is pretty well insulated because that ASHP output is quite a bit lower than most domestic boilers - unless you live somewhere warmer than the UK!
So I think my comments may only apply to large houses with relatively poor insulation (like my own).
Haha... well insulated... I wish!Those figures suggest your house is pretty well insulated because that ASHP output is quite a bit lower than most domestic boilers - unless you live somewhere warmer than the UK!
So I think my comments may only apply to large houses with relatively poor insulation (like my own).
It's a solid wall Georgian property! The loft is well insulated and the "modern" extension cavity wall is filled, but that's about it.
The ASHP works because it delivers a constant flow of gentle heat rather than the peaks of intense heat from the old oil boiler. It's got rid of the damp and condensation too!
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