Bivalent ASHP and oil boiler

matt_drummer

Reed_Richards said:

matt_drummer said:

What I have done is banked my solar generation when I had too much so that I could use it when I need it.

Why is this so difficult for you to understand?

Glad to see you back, @matt_drummer .

 It's not too difficult to understand, although you are absolutely correct, it is outside my own experience.  I think what you sometimes forget is that your solar panel system is much larger than the average one.  I am limited to exporting 3.68 kWh per hour and the maximum I can generate is 4.8 kW.  So there is no way I could ever come close to exporting 70 kWh per day as you do.  It's really great what you have, but usual.  Hopefully @greenbee has the roof area and DNO permission to set up, and get the full benefit from, a large solar array like yours.     

Hi Reed,

I am not really back, just a prelude to wrap up my heat pump story.

The problem is, you state as an absolute fact, that @greenbee could not run their heat pump from solar panels in the winter as the sun isn't shining.

That is not entirely true, they say they have ample roof space and with the correct permissions they could do this.

You may not be able to but this isn't about you.

What you could have said is that, it may be possible to use solar panels to generate enough income in the sunnier times to fund your heat pump consumption when you need it, and I know somebody that is doing it.

But you don't do that, you just say that heat pumps and solar panels don't go together as the sun isn't shining when you need heat.

It's not very helpful and narrow minded, just focussed on you and your system, if it's not like yours then it won't work.

It's what it feels like, your way is correct and everything else is wrong.

I don't think I have been unfair here.

I am sure you are a decent person but it's a big world and there are plenty of smarter people out there than even you or me.

There are other ways of doing things, some much better, listening and sharing helps, negativity based on just our own ways of doing things will not make anything better. Just because you or I don't understand it doesn't make it impossible.

QrizB

Edit: having written the post below, I realise it might come over as antagonistic.

It's not meant to be "having a go" at Matt, I'm just trying to point out that he's in a privileged position and it's not reasonable to claim that any particular forumite could do the same as he has.

I don't know greenbee's position and they might have large enough property, and a plump enough bank account, to do the same. But, unless they choose to share this info with us, I don't think we should assume that they do.

--------

matt_drummer said:

In the spring and summer I was generating 80kWh a day of electricity at times but I don't use that.
I got paid for exporting more than 70kWh a day at times as I just don't use that much electricity in the sunny months.

That needs what, a 15kWp solar array? So £18k worth, and roughly 75 square metres of roof/garden space? That's a lot of capital and real estate.

matt_drummer said:

Anybody with enough roof space and sufficient funds to buy the solar panels could do what I have done. You don't need a huge mansion to do it, my house is 98m2 with a 40m2 garage, I have about 80m2 of roof space that is filled as much as I can with solar panels, maybe 60% of the roof area.

I'll gently put it to you that your house is at least twice as large as the typical 3-bed semi, your garage being as big as  many houses, and (judging from Zoopla) it's probably a £1M+ home.

matt_drummer said:
There's no magic in this.

Beyond being in the top 10% of UK population for wealth, of course.

matt_drummer said:
Why keep telling people that it is not possible?
@greenbee could do exactly the same as me.

If they happen to be a millionaire with an interest in net zero, yes they could.

matt_drummer

QrizB said:

matt_drummer said:

In the spring and summer I was generating 80kWh a day of electricity at times but I don't use that.
I got paid for exporting more than 70kWh a day at times as I just don't use that much electricity in the sunny months.

That needs what, a 15kWp solar array? So £18k worth, and roughly 75 square metres of roof/garden space? That's a lot of capital and real estate.

matt_drummer said:

Anybody with enough roof space and sufficient funds to buy the solar panels could do what I have done. You don't need a huge mansion to do it, my house is 98m2 with a 40m2 garage, I have about 80m2 of roof space that is filled as much as I can with solar panels, maybe 60% of the roof area.

I'll gently put it to you that your house is at least twice as large as the typical 3-bed semi, your garage being as big as  many houses, and (judging from Zoopla) it's probably a £1M+ home.

matt_drummer said:
There's no magic in this.

Beyond being in the top 10% of UK population for wealth, of course.

matt_drummer said:
Why keep telling people that it is not possible?
@greenbee could do exactly the same as me.

If they happen to be a millionaire with an interest in net zero, yes they could.

Hi,

Saying it is not possible to do it without spending money is true, but @greenbee never said they wanted to do it for nothing, they said they had plenty of roof space and were told that solar panels would never run a heat pump in the winter.

That is my objection, or point of contention, whatever you might call it.

At no point have financial constraints been mentioned, just that it doesn't work.

Even if it was £18k for the solar panels that's not a bad deal, they easily pay for themselves over their lifespan and then some plus I don't burn anything, which was the whole point of this.

I don't think you need to be a millionaire to spend £18k on solar panels, you just need £18k or somebody to lend you £18k, like a bank as I did!

You don't have to do it all i one go, I didn't and you probably don't need the 13.6kW of solar panels I have to generate enough electricity in a year to run a heat pump. It doesn't have to be all exported, just generated, as long as you use it or export it 3,500kWh of generation pays for 3,500kWh of heat pump use, you may have used it on something else in the summer but you would have paid for that anyway without the solar panels.

My house has a foot print of about 40m2 and the garage about 35m2, hardly a mansion and certainly not £1m, have you ever been to Ipswich! We bought it for £380,000 two years ago. It is not a big house at all. The house we moved from was a 3 bed semi with about 80m2 of total floor area (so 40m2 foot print) and this is a 4 bed detached that is 20% bigger at most in terms of floor area and foot print, it's really pretty modest.

My electricity consumption is about 8,000kWh a year, that would cost me about £2,160 a year so the panels pay for themselves in 8 years or so assuming prices stay as they are now. It's quite a good return even if i just broke even which I should probably do better on. Edited to add, of course I forgot the other 4,000kWh over my usage that I get paid for which are worth another £900 or so. My total annual benefit from the panels is actually £3,000 so they pay for themselves in six years or less, pretty good I think! After that they will still produce electricity and I will still run my heat pump and everything else and still be paid for my exports. At today's rate I will still pay nothing for energy and have an income of £900 + per annum from my solar panels. How can anybody say it doesn't work or isn't possible?

I don't know whether I am in the top 10% of earners, I suspect not, but I do earn more than average I will admit, although not as much as I am really worth

Rather than say it's not possible, why not say it is possible but at a cost?


I do understand that what I have done is beyond many if not most people, but saying it won't work and isn't possible just isn't true.

matt_drummer

QrizB said:

Edit: having written the post below, I realise it might come over as antagonistic.

It's not meant to be "having a go" at Matt, I'm just trying to point out that he's in a privileged position and it's not reasonable to claim that any particular forumite could do the same as he has.

I don't know greenbee's position and they might have large enough property, and a plump enough bank account, to do the same. But, unless they choose to share this info with us, I don't think we should assume that they do.

--------

Surely that is up to them to decide?

I haven't claimed they could or could not, they have been told they couldn't do it as the sun isn't shining when they need the heat pump.

Telling them it won't work is not the correct answer.

I don't think it is correct to make any assumptions either way as to somebody's finances, just answer the question about whether solar panels would work, caveat it if you feel it necessary. Assuming they don't have the funds to do it is the wrong starting place for me.

They have already said they are considering solar panels as they have a lot of roof area, nobody told them they couldn't afford solar panels, they were told it wouldn't work.

This is somebody who is talking about getting a heat pump because they are worried about running  out of oil, I don't know and it is none of my business but it does not sound like a person struggling to make ends meet?

It will work if they have the property to do it and the funds, wherever they may come from.

You don't have to be rich, I'm not, just smart enough to do the sums, which I am and I did, and it works for me.

My personal circumstances are irrelevant, I'm not poor but I am not rich either.

You don't need to be a millionaire, just a reasonably good job and a good credit history.

Nothing I have done is that extravagant, it pays for itself in a little over the time and amount of a modest car finance agreement and then generates an income of at least £3,000 a year at todays energy costs.

It was a smart move by a smart person, not the actions of a reckless billionaire!



I would add that you don't need to generate that much to run a heat pump or contribute to running a heat pump.

Even an average sized array generating 4,000kWh per annum will pay for the heat pump consumption in an average house.

It doesn't matter at what point of the year you consume or get paid for that generation.

If you have no solar and then get a heat pump and solar your annual electricity consumption net of the solar generation will not change and therefore the solar panels pay for the heat pump consumption.

An example is necessary:)

No heat pump and no solar.

Annual consumption 3,000kWh at a cost of 28p per kWh is £840


Heat pump without solar

Annual consumption 6,500kWh at a cost of 28p per kWh is £1,820


Heat pump with solar generating 4,000kWh pa (all solar consumed)

Annual consumption 2,500kWh (6,500 - 4000) at a cost of 28p per kWh is £700


Heat pump with solar generating 4,000kWh pa (50% solar exported)

Annual consumption 4,500 kWh (6,500 - 2,000) at a cost of 28p per kWh is £1,260 minus income from export of (2,000 x .15) £300 is a total of £960



Is it not clear that the solar generation, even at a modest level, pays for most of if not all of the cost of the heat pump consumption?

It doesn't matter when the solar is generated, it just goes into the pot of annual electricity consumption and cost.

It is always beneficial to add as much solar as you can and it will contribute to or even cover the cost of running a heat pump.

No millionaires or massive estates necessary

greenbee

This discussion seems to have got rather heated, and personal. I think the point that everyone's circumstances differ is worth emphasising - so it's probably best think of it as a theoretical problem (like in an exam) rather than trying to relate it to personal experience.

I'm not a millionaire (every month I hope my premium bonds will change this), but I have already stated that this is a 5 bed house with a total floor area of around 3000 sq ft., and plenty of roof on both the house and garage (probably big enough to go for something the same size as @matt_drummer according to the people who've looked), I am in an area where investment in renewables is positively encouraged by the planners and investment in the grid infrastructure has been made to support both macro- and micro-generation (admittedly mostly for the benefit of London rather than the local population, but we are trying to reap the benefit of it) and have already stated that I'm not looking for a grant, but planning to pay for this myself - I've already worked out that it's affordable and that the numbers pretty much stack up..

I work from home, so solar plus EPS makes sense financially to avoid me having to commute 2.5 hours (if I'm lucky) each way to the nearest office/recording studio in the event of a power outage (and yes, I already have redundancy in my options for internet access, currently supported by ancient UPS equipment) or get on a plane to have meetings in person instead of online. I earn enough money and am in a specialised enough role for it to be worth my while investing in something that improves both my working life and our home life.

If, over time, this investment also helps us reduce out dependence on fossil fuels, that will also be a benefit. We had solar-thermal on my parents' house 40-odd years ago, so the technology isn't entirely new to me. I spent part of my working life in the energy industry. I helped the heating engineer service my oil boiler and megaflo tank recently (in a very hands-off way, just in case anyone mentions certification, but I do understand how both of them work). However, hybrid and bivalent systems are new to me, so was interested in people's thoughts (and ideally experience) - bivalent looked like an opportunity for transition and an investment in resilience. Clearly I have more research to do, but the initial discussions with and calculations by the electrician, heating engineer and my friends suggest that it could do what we need with minimal disruption (and make financial sense - to us, in our particular non-millionaire financial circumstances). 

matt_drummer

My house is less than 1,000 square feet (that is in total for both floors) and my garage is about 400 square feet.

I'm sorry for the others,

They could have just told you that solar panels work really well and it doesn't matter when you generate the electricity as long as you consume it or get paid for it when you export it.

Whatever you do, solar panels will contribute to your annual energy costs.

I'll leave it to you to decide whether you think they make sense to your personal circumstances

Reed_Richards

When someone posts here, it can be difficult to judge how well-educated they have made themselves on what they plan to do.  Some people appear quite naïve about what they can achieve with solar panels so when I post I try to make sure that they do understand the limitations.  Perhaps I over emphasise the limitations?  @greenbee has clearly given what they propose some thought with regard to the solar panels; I apologise if my comments were too simplistic and did not cover the very reasonable approach, where feasible, of funding winter electricity use from the summer export revenue.

I'm not aware that anyone who posts here has a hybrid heat pump system.  When I was seeking quotes, Grant offered me a hybrid oil boiler/ASHP system but when they did the calculations it turned out that a heat pump alone would be quite sufficient.  My personal prejudice would be to opt for a heat pump alone, if that is feasible.  That's really just on the basis that there is more risk if you make something more complicated than it needs to be.  But at current prices, to make a heat pump cheaper to run than an oil boiler you probably need to confine the use of the heat pump to spring, summer and autumn so a hybrid system makes economic sense in terms of running costs.  

  

matt_drummer

Reed_Richards said:

When someone posts here, it can be difficult to judge how well-educated they have made themselves on what they plan to do.  Some people appear quite naïve about what they can achieve with solar panels so when I post I try to make sure that they do understand the limitations.  Perhaps I over emphasise the limitations?  @greenbee has clearly given what they propose some thought with regard to the solar panels; I apologise if my comments were too simplistic and did not cover the very reasonable approach, where feasible, of funding winter electricity use from the summer export revenue.

I'm not aware that anyone who posts here has a hybrid heat pump system.  When I was seeking quotes, Grant offered me a hybrid oil boiler/ASHP system but when they did the calculations it turned out that a heat pump alone would be quite sufficient.  My personal prejudice would be to opt for a heat pump alone, if that is feasible.  That's really just on the basis that there is more risk if you make something more complicated than it needs to be.  But at current prices, to make a heat pump cheaper to run than an oil boiler you probably need to confine the use of the heat pump to spring, summer and autumn so a hybrid system makes economic sense in terms of running costs.  

  

I agree Reed.

I would just go with a heat pump.

I don't know the price of oil but I think gas is about 8p per kWh, I don't buy it anymore

My electricity cost today is a maximum of 23p per kWh although it might be as low as 17p per kWh, I can't be bothered to work it out right now.

But at 23p per kWh my heating cost today will be 5.5p per kWh maximum and possibly as low as 4.0p per kWh

Definitely cheaper than gas and I would imagine cheaper than oil?

And the bonus is I haven't burnt anything in Ipswich


Edited!

Forgot to add, I'm not paying for it either!


My wife was just asking about this, how much we are paying compared to gas.

As I said to her at the end, I can generate electricity/the funds to pay for electricity but I cannot extract my own oil or gas.

The important part is that we are protected as long as export payments follow import prices, otherwise we were at the mercy of the markets. It was the second biggest part of the project, the first being to stop burning stuff.

greenbee

Overall just using the heat pump probably would cost less BUT the cost (and disruption) of upgrading all the pipework and the radiators needs to be taken into account. So it isn't entirely straightfoward. The boiler should, if looked after properly, last a while longer - and hopefully by the time it needs replacing, most of the work needed to upgrade the heating will have been done - because as each room is renovated we will upgrade. But taking up every floor in the house isn't something we have the energy to do - hence trying to find an option that will give us a gradual transition. A hybrid boiler is off the list too, because the boiler doesn't need replacing yet - and the ASHP being integrated would mean that we might actually end up dependent on oil for longer. 

It's complicated. But it's also good to know that there are compromise options out there. Assuming they work, and the costs stack up. 

QrizB

If you think you need plumbing improvements to make use of a heat pump, won't you need those same improvements anyway if you plan to run a heat pump in parallel with your oil boiler?

By keeping the oil boiler, you still have the ongoing maintenance costs and an oil tank in your garden that you'll still worry about running low / out when you need it. And you won't qualify for the £7.5k boiler upgrade scheme grant. Plus, if you fit an undersized HP just to supplement the boiler, you'll need to replace it again when you finally give up on oil.

I might be missing something, but I don't think you've made a clear case for keeping both - other than redundancy.