solar panels v heatpump

[monabri]

With the HHR Storage rads, don't they need an electrical socket to power a fan? This might be an additional cost to install. I do wonder as to how much of an efficiency increase they are over normal storage rads.

[Mike4]

Bear in mind air to air heat pumps are cheap because they don't heat your hot water.

And solar panels work best when you need them the least, and vice versa.

[monabri]

Heat pump cost = initial cost + maintenance

Expected life = 20 years ( guess)

Annual average cost = X

Annual cost saving = Y

Not knowing "Y" is the tricky bit in determining the break even time.

If you were to only install the heat pump, would this mean you could get away with your existing conventional storage rads?

( monabri..with a genuine interest , E7 storage rads, no gas, open plan, and mindful 1 medium storage rad= 23% of our annual fuel bill..)

Snorvey...could you provide a link to the information on the ASHP svp?

[Mike4]

I dont think the panels would be that effective at all. I've seen less estimates of less than 1kw from a 3.3kw system on a decent winters day.

This needs particular comment. Many people who keep track if their solar panel output say on a dull winter's day it falls to approx 10% of rated output. So you'd be getting 0.33kW on a dull December afternoon not the 1kW you mention.

Further to this my own experience of having 560W of solar panel on my boat when I lived aboard, output from those (quite expensive, good quality) panels fell to nearer 1% of rated output on that same December afternoon, especially if it was slashing with rain. I think this effect is because boats on canals are nearly always near trees, so the panels can rarely 'see' the whole of the sky.

[BullDog]

Looks to me like for simplicity, reliability and lowest likely overall lifetime cost of ownership, the modern E7 storage heaters are the best option.

Part of that strategy would be to timeshift all washing machine, tumble dryer, dishwasher use into the E7 period. Along with water heating overnight too. Which basically means the economics of a solar PV array have to compete with E7 tariff electricity rather than daytime tariff. Much more difficult to justify on capital cost and returns on investment.

[BullDog]

Looks to me like for simplicity, reliability and lowest likely overall lifetime cost of ownership, the modern E7 storage heaters are the best option.

Part of that strategy would be to timeshift all washing machine, tumble dryer, dishwasher use into the E7 period. Along with water heating overnight too. Which basically means the economics of a solar PV array have to compete with E7 tariff electricity rather than daytime tariff. Much more difficult to justify on capital cost and returns on investment.

Yes, I'm thinking this too. It's really heat pump on full price leccy v Dimplex (or similar) HHR on E7

And..... using the money left over buy shares in SSE or whoever you choose. They're investing in many renewable energy projects and you can then use the dividends to help pay the electric bill.

Last time I looked at Solar PV it couldn't compete with buying SSE shares over a twenty year period. After twenty years I would either have a scrap PV system or still own SSE shares that paid dividends and at the end of the period I still had the shares too.

Now that I have a BEV overnight tariff that I timeshift energy use into, Solar PV is even more uneconomic. We are presently achieving about 65% total use of electricity into the BEV tariff period*. Ofcourse I still have SSE shares paying dividends too.

* That includes local driving too so displaces petrol purchases as well.

[AsleepInYorkshire]

I'm still looking at replacing the aging, but still effective storage heaters in my house, but I've also been giving a great deal of thought to solar panels and/or a heat pump or new high heat retention/far more controllable storage heaters.

It would cost me about 5k for solar panels on my roof and I reckon about 2.5k for a heat pump*. Dimplex Quantum HHR storage heaters would cost me about £1200.

*air to air mini split ducted to the 2 main living areas in the house which is mostly open plan.

We've seen elsewhere on here that heating is by far the biggest cost of your house, so when the panels are most effective in the summer, I dont really need the energy they produce and I'm faced with either spending even more ££££ on batteries or to sell the excess back to the grid at a pittance. In the winter, at my latitude, I dont think the panels would be that effective at all. I've seen less estimates of less than 1kw from a 3.3kw system on a decent winters day.

*I think* A heat pump is half the cost of the panels and would be far more effective when I need it (the winters are comparatively mild here & its rarely below freezing). Although the heat pump would be operating on full price electric (which is double the cost of E7), the supposed COP of 3-4 of the heat pump would make it cheaper than the storage heaters. Again, *I think*

So I'm leaning towards the heat pump, although new HHR storage heaters would be far simpler to replace and I wouldn't need a big metal lump outside the house). I think it's far more Effective for my ££ than solar panels, as long as I keep my E7 for water heating and washing. I may need to keep/replace the storage heater too depending on how effective the heat pump is.

WRT to ongoing maintenance, I believe heat pumps need to be serviced, panels do not and storage heaters dont need looking at either.

Any thoughts welcome. Apologies for the ramble!

No gas/economy7/storage heating & hot water heated overnight/LED lighting/well insulated/new double glazing/washing machine On E7 timings/100% green electric/generally 1-2 people in the house all day/high end heat pump e.g Daiken.

Heat pump before solar panels from a cost return point of view.

Daiken or Mitsubishi are the market leaders I believe. Mitsubishi seem to have a higher reliance regarding maintenance. Don't oversize the heat pump if you go down that route. There's some upside with heat pumps as they can be used to cool in summer albeit you will have to install ducting etc. I've not really got much knowledge regarding modern heat storage radiators.

AiY(D)

[Midsmartin]

There is also solar thermal - ie solar water heating. We installed this years ago when photovoltaics were much more expensive.
It works well - the gas bill is essentially zero in the summer months, specially if you can time your water use to match when it is heated up.
The downside is that you need a whole new hot water tank.

Over the winter of course it does less, but still preheats the water tank whenever there's a bit of sun.
It needs occasional maintenance. We've just had the fluid in it swapped, and the pump failed once.

[melonfool]

Don't forget there are some grants towards installing heat pumps, which might just make it worthwhile.

Mel

[funduffer]

I have had solar PV for 2 years. It is great, but not a solution for heating the house in winter months. I also have a BEV, and use either cheap overnight electricity, or the solar PV to charge it. Works out at less than 2p per mile overall (ignoring public charging). I can confirm that my PV generates power at about 15% in Dec/Jan compared to that in June/July. I am talking Yorkshire, not south of France!

For heating, I have a 7 year old Vaillant combi gas boiler and radiators, but I am starting to think about what I would replace it with when it reaches the end of it's life. My wife also wants some air conditioning after last summer's extreme temperatures, so I have been looking at Daikin air-to-air heat pumps with air con units. I have just received a quote for 2 Daikin units (each with their own heat pump due to installation restrictions), and they work out at about £3.5k for both / £1.7k each, including installation. Note, there is no VAT on these as they are 'renewable energy' products. I would have one in the living room and one in the bedroom.

My idea is to have the two heat pumps and air con units to run alongside the conventional gas boiler. This is so I can learn how to use them effectively and respond to the price variations between gas and electricity. Currently, the energy price guarantee has electricity at 34p/kWh and gas at 10p/kWh, which is a ratio of 3.4. This is about the same as the SPOC of heat pumps, so ignoring any efficiency difference, the cost of providing a kW of heat should be about the same. On efficiency, I think the heat pump would be much more efficient that a boiler+radiator heating system, but I don't have figures for this. The air con in the summer is a bonus, and probably almost free due to the solar PV power available when the sun is shining.

I think I am going to proceed with this, so I will post about it after they have been installed and I have some data.

Whilst I believe the solar PV will pay back in 7 years, I really have no idea what the payback period would be for the heat pumps+air con units. I see it more as future-proofing my property against the huge unknowns regarding energy costs in the coming years, and providing a pointer as to how to replace my gas heating system when the time comes.

I am 67, and I intend to stay in this property until they take me out in a box!

FD

[BullDog]

I presume that if you have a heat pump installed, it has to have an annual service to maintain any warranty cover?* Given that a simple annual gas boiler check comes in typically £65 or so. Then how much does the industry charge for a heat pump system service? I imagine there's cleaning heat exchanger fins, cleaning fan blades, checking condensate drains, changing compressor oil and filter, checking and regassing the refrigerant etc... ? I am guessing that's what an annual heat pump service involves. Cost? Given the dire shortage of anyone who understands these units, I suppose they can charge whatever they feel people will pay?

* When I rented an apartment for three years that had ASHP heating/cooling it was never serviced while I lived there, but that's because it's an avoidable cost overhead to the landlord. I believe.

[BullDog]

I have had solar PV for 2 years. It is great, but not a solution for heating the house in winter months. I also have a BEV, and use either cheap overnight electricity, or the solar PV to charge it. Works out at less than 2p per mile overall (ignoring public charging). I can confirm that my PV generates power at about 15% in Dec/Jan compared to that in June/July. I am talking Yorkshire, not south of France!

For heating, I have a 7 year old Vaillant combi gas boiler and radiators, but I am starting to think about what I would replace it with when it reaches the end of it's life. My wife also wants some air conditioning after last summer's extreme temperatures, so I have been looking at Daikin air-to-air heat pumps with air con units. I have just received a quote for 2 Daikin units (each with their own heat pump due to installation restrictions), and they work out at about £3.5k for both / £1.7k each, including installation. Note, there is no VAT on these as they are 'renewable energy' products. I would have one in the living room and one in the bedroom.

My idea is to have the two heat pumps and air con units to run alongside the conventional gas boiler. This is so I can learn how to use them effectively and respond to the price variations between gas and electricity. Currently, the energy price guarantee has electricity at 34p/kWh and gas at 10p/kWh, which is a ratio of 3.4. This is about the same as the SPOC of heat pumps, so ignoring any efficiency difference, the cost of providing a kW of heat should be about the same. On efficiency, I think the heat pump would be much more efficient that a boiler+radiator heating system, but I don't have figures for this. The air con in the summer is a bonus, and probably almost free due to the solar PV power available when the sun is shining.

I think I am going to proceed with this, so I will post about it after they have been installed and I have some data.

Whilst I believe the solar PV will pay back in 7 years, I really have no idea what the payback period would be for the heat pumps+air con units. I see it more as future-proofing my property against the huge unknowns regarding energy costs in the coming years, and providing a pointer as to how to replace my gas heating system when the time comes.

I am 67, and I intend to stay in this property until they take me out in a box!

FD

I find this topic very interesting.

I presume that when calculating the return on investment of the solar PV the seven year pay back includes - annual write off of capital cost over PV system life time, loss of dividend income on an alternative investment of the same money and presumes electricity at the lowest overnight unit cost? When I try that calculation at my current overnight BEV charging tariff I don't come anywhere close to a seven year simple payback.

Presently we are timeshifting about 65% of our electricity consumption into the BEV tariff period. And my SSE shares are contributing handsomely in dividends. For us it makes no sense to invest the money we have in SSE into a solar PV array.

Hopefully, there's some capital growth to look forward to from the SSE shares long term but I am ignoring that. I think that could potentially be the biggest factor over a 25 year projected life of a solar PV system though!

[funduffer]

I presume that if you have a heat pump installed, it has to have an annual service to maintain any warranty cover?* Given that a simple annual gas boiler check comes in typically £65 or so. Then how much does the industry charge for a heat pump system service? I imagine there's cleaning heat exchanger fins, cleaning fan blades, checking condensate drains, changing compressor oil and filter, checking and regassing the refrigerant etc... ? I am guessing that's what an annual heat pump service involves. Cost? Given the dire shortage of anyone who understands these units, I suppose they can charge whatever they feel people will pay?

* When I rented an apartment for three years that had ASHP heating/cooling it was never serviced while I lived there, but that's because it's an avoidable cost overhead to the landlord. I believe.

This is a good question, and one I have asked about, before committing to the 2 heat pumps!

[funduffer]

I find this topic very interesting.

I presume that when calculating the return on investment of the solar PV the seven year pay back includes - annual write off of capital cost over PV system life time, loss of dividend income on an alternative investment of the same money and presumes electricity at the lowest overnight unit cost? When I try that calculation at my current overnight BEV charging tariff I don't come anywhere close to a seven year simple payback.

Presently we are timeshifting about 65% of our electricity consumption into the BEV tariff period. And my SSE shares are contributing handsomely in dividends. For us it makes no sense to invest the money we have in SSE into a solar PV array.

Hopefully, there's some capital growth to look forward to from the SSE shares long term but I am ignoring that. I think that could potentially be the biggest factor over a 25 year projected life of a solar PV system though!

The payback on PV solar is calculated from 2 components - the saving of electricity costs by using free solar energy during the daytime, and the money received by exporting excess solar power. Overnight usage is irrelevant (unless you have a battery), as my panels never generate anything at night! As daytime electricity prices rise (as they have done recently), the payback period gets shorter as the first component gets larger. The second component is also getting larger as energy companies are starting to offer higher rates for exported power.

Compared to the estimate my solar provider provided, after 2 years, the payback is slightly better than they predicted, largely due to the rising cost of electricity.

Oh yes, and I have a substantial shareholding is SSE, as well as many other dividend-paying shares. I think if I had decided to follow your strategy, which I have no problem with, I would have spread the capital costs across more than just one company.

FD

[BullDog]

I find this topic very interesting.

I presume that when calculating the return on investment of the solar PV the seven year pay back includes - annual write off of capital cost over PV system life time, loss of dividend income on an alternative investment of the same money and presumes electricity at the lowest overnight unit cost? When I try that calculation at my current overnight BEV charging tariff I don't come anywhere close to a seven year simple payback.

Presently we are timeshifting about 65% of our electricity consumption into the BEV tariff period. And my SSE shares are contributing handsomely in dividends. For us it makes no sense to invest the money we have in SSE into a solar PV array.

Hopefully, there's some capital growth to look forward to from the SSE shares long term but I am ignoring that. I think that could potentially be the biggest factor over a 25 year projected life of a solar PV system though!

The payback on PV solar is calculated from 2 components - the saving of electricity costs by using free solar energy during the daytime, and the money received by exporting excess solar power. Overnight usage is irrelevant (unless you have a battery), as my panels never generate anything at night! As daytime electricity prices rise (as they have done recently), the payback period gets shorter as the first component gets larger. The second component is also getting larger as energy companies are starting to offer higher rates for exported power.

Compared to the estimate my solar provider provided, after 2 years, the payback is slightly better than they predicted, largely due to the rising cost of electricity.

Oh yes, and I have a substantial shareholding is SSE, as well as many other dividend-paying shares. I think if I had decided to follow your strategy, which I have no problem with, I would have spread the capital costs across more than just one company.

FD

Thanks it is a really interesting topic with no easy single answer. The reason I use the overnight BEV tariff when calculating return on the solar PV is that I have deliberately timeshifted the large white goods power consumption and PHEV charging into the BEV tariff period. So, if I had solar PV to run the white goods during the day it would be displacing low cost overnight tariff use rather than higher cost day time tariff use*. My choice of SSE shares rather than solar PV is ofcourse quite arbitrary. But they are UK leaders in the large scale renewables projects space. So by my logic I am kind of subcontracting my generation of renewable power to them rather than it taking place on my roof top. All the best.

* If you already haven't, I suggest you look at your energy supplier to see if they're participating in the new scheme being introduced by National Grid where they plan to pay consumers to run white goods overnight. I have registered to participate if and when the scheme goes live.

[taken2often]

This post seems to cover most of the problems that we are supposed to face for the future. This is my take on it.

Air Sourced Heat Pumps. Under the right conditions great, if not right very bad. The first benefit is that you can screw the working poor out of £5k
to help fund the installation. If you have a good air tight house,well insulated with Under floor heating. This could be a great system.The only down side is is the annual service cost. It seems there is plenty of installers but very few service engineers. The other thing is it needs to be on 24/7 or it cannot keep up with very low temps and if you use a time clock that we all love.

Now a different type of air sourced pump may be your standard Air Con Unit for your lounge and electric oil filled heaters in the other rooms. I have mine all set at 12c and very rarely come on, but ensure the house will never realy get cold. The 80 ltre electric water tank is on 24/7 at 55c and a random 65c. This cost buttons during the summer season. As alwayas its the heating that costs. As I do not have the above AC unit I have to decide will I turn up the radiators or put on a fan heater for quick comfort. This tends to give you the same effect as a AC unit. For a two three hour period in the lounge it appears to be a good option. Who would have thought.

Air sourced heat Pumps will be a massive scandal in due course as many systems will be fitted in the wrong property by the wrong people.

Bob

[UncleEbenezer]

It seems there is plenty of installers but very few service engineers.

That at least will change, just as soon as there's more work for the service engineers to do. Indeed, if it follows anything like the gas boiler model, those who install them will be very keen to do your servicing too!

Chap who installed my new boiler said he was just waiting for a government incentive to train and qualify to deal with heat pumps. I expect a fair few of his (or our Mike's) peers - at least those in early/mid career - are in a similar place.

I still want a river-sourced heat pump: there are good reasons for it to beat either air or ground sources hands down. But in practical terms, I'm not going to replace a nearly-new boiler that's doing a good job.

[Mike4]

This post seems to cover most of the problems that we are supposed to face for the future. This is my take on it.

Air Sourced Heat Pumps. Under the right conditions great, if not right very bad. The first benefit is that you can screw the working poor out of £5k
to help fund the installation. If you have a good air tight house,well insulated with Under floor heating. This could be a great system.The only down side is is the annual service cost. It seems there is plenty of installers but very few service engineers. The other thing is it needs to be on 24/7 or it cannot keep up with very low temps and if you use a time clock that we all love.

Now a different type of air sourced pump may be your standard Air Con Unit for your lounge and electric oil filled heaters in the other rooms. I have mine all set at 12c and very rarely come on, but ensure the house will never realy get cold. The 80 ltre electric water tank is on 24/7 at 55c and a random 65c. This cost buttons during the summer season. As alwayas its the heating that costs. As I do not have the above AC unit I have to decide will I turn up the radiators or put on a fan heater for quick comfort. This tends to give you the same effect as a AC unit. For a two three hour period in the lounge it appears to be a good option. Who would have thought.

Air sourced heat Pumps will be a massive scandal in due course as many systems will be fitted in the wrong property by the wrong people.

Bob

I mostly agree. People do get hung up on the source of the energy though, when the method of output is just as, or more important. An air source heat pump delivering hot air costs buttons compared to an air source heat pump delivering hot water for rads and taps. My current view is a hybrid system is best. Air source heating which brings the by-product mahoosive benefit of cooling in summer. And leccy, gas or solar for hot water.

Main problem with this is the guvermint disapproves and will not chip in with the £5k grant.

[BullDog]

Solar batteries are units that charge off your solar panels; These allow you to store the excess electricity that is generated for later use.

They don't even have to charge from solar panels! If you receive cheaper electricity during certain times (e.g. overnight), you can charge the batteries when rates are cheaper and use it when it would be more expensive.

Combine charging from the mains during cheaper rates, with your solar panels generating in the day, and you'll get super savings!

Ok, so I'm now leaning towards binning the solar panel idea AND the heat pump and concentrating on upgrading the storage heaters to modern HHR models. Dimplex, Elnur and Electrorad do models which claim to be around 27% more efficient than older storage heaters and far more adaptable/controllable etc. Replacing the main heater would cost about £850 plus the electrician to hook it up. A smaller one for the kitchen diner maybe around £500 depending on the size.

I am enquiring about battery storage because I read that some types will charge from Economy7 (similar to the storage heaters I guess). It all comes down to is it cost effective?

Perhaps you already thought about this. But anyway, rather than buy batteries to charge on off peak electricity which I would then use to run white goods, I now set the timer built into each of my white goods appliances and run them at night. Upfront cost, zero. The only significant things that run continuously on day time tariff here therefore are refrigeration appliances. And they cycle on/off anyhow. So they're not a continuous load.

[Mike4]

Ok, so I'm now leaning towards binning the solar panel idea AND the heat pump and concentrating on upgrading the storage heaters to modern HHR models. Dimplex, Elnur and Electrorad do models which claim to be around 27% more efficient than older storage heaters

You've mentioned this before but I am driven to call this out as techno-babble. All storage heaters are 100% efficient as they convert ALL the leccy they burn into heat, inside your house. Even the very old ones.

Also this HHR thing. The high density ceramic bricks inside conventional storage heaters are hard to beat for energy density without stepping up to steel or cast iron, which is about 20 times the price for double the heat capacity performance. What IS this new HHR material they are using? I bet it is just the same ol' ceramic bricks. Besides, one doesn't want "high heat retention" in a storage heater. One needs the bricks to give up their heat quickly and easily on demand. It's the demand mechanism that needs controlling.

Ah that's better. Rant over.