Solar, battery or Ripple plus air pump in near future question

slewis1972

Hi All

So, like others looking at solar. I am moving house ( to 4 bed detached) South east england, have a hip roof (square house) so can face south /south east , not shaded that I can see.
There is 4 adults in the house and I dont see 2 of them (older kids) leaving in near future. My wife works from home and I can also.

Current useage is 4300 Kwh on electric.

Boiler in new house is 7 years old plus original hot water cylinder (house is 23 years old), we are looking at heat source air pump with new cylinder via Octupus. I know someone who has a similar size house with a new heat pump and they reckon its 4000 Kwh for a year in electricity.

So questions I have: 

So, do I go for as many panels I can but have a feeling on the 2 parts roof I can see will be best for direction, maybe 6000 Kwh+ but am hoping for more (if I need)

• If thats the case, do I go for a larger battery and top up via Octupus Flux tariff (when available) in night when solar is not able to in daytime? I then heat the hot water at cheapest time and top up in daytime.

• Or do I dont look at battery but look at RippleEnergy and their new solar scheme as a top? But then it wont come on for a few years. The people I know who have a hear source air pump use Ripple (wind farm one)  already but dont have solar.
• 
  
• Or don't look at batteries and just go for largest number panels. Export what I don't use.

• Or, as boiler I think is still is a decent Worcester Bosch Greenstar condensing boiler, do I replace the hot water cyclinder and using emersion part, use the electric (with or even without battery if I heat in daytime) and do the hot water by that. As that I reckon is approx 20% of the total cost maybe of gas. But then the boiler will be minimally used for most of the year.

I wont go for cheap panels based on comments. Its just the setup I need to consider considering the electricity useage.When at best months of course I will send back to the grid.

Any comments appreciated.

Screwdriva

You're fortunate to have a S/ SE aspect. If you decide to go with a heat pump, this will help immensely.

Octopus install Daikin ASHPs exclusively. Here's a recent, quality installation with actual SCOP breakdown for DHW and heating during the recent cold waves, without the need for a gas backup. The video should show that the Vaillant heat pump will cost quite a bit less to run compared to gas, assuming the house is reasonably insulted and the emitters are sized appropriately. And that's without factoring the benefit of PV into the equation! (You will need a new double coil hot water cylinder and T22 or T23 radiators at a minimum. Perhaps underfloor heating as well)

I know of several households that have invested in batteries and others with excellent aspects like yours, who run ASHPs off the grid with pure Solar PV and no battery. Investing a battery would mean a life of 10-12 years before reinvestment is required. Investing in Ripple will likely last 3-4X longer.

I'd recommend using this calculator to generate an ROI forecast with/ without a battery, using the heat pump targeted tariffs. Then factor in the Ripple return on top of non-battery option, and you should have an answer. 

Alnat1

Have you considered how suitable the current central heating system is to retrofit an ASHP? We found it's more complicated than we first thought.

We live in what sounds a very similar property (4 bed det. built 2003) and our gas CH system has microbore flexi pipes which are all hidden away behind the plasterboard and emerge, around 30cm above skirting height, behind each radiator. Beside needing larger radiators in most rooms we would also probably need to renew most of this pipework for an ASHP to work efficiently. This would also mean every room in the house would need some re-boarding and then redecorating. It may be that the house your buying was built in a similar way. If so, would you be happy with all the extra expense?

Octopus are running a great scheme but it's been mentioned by others on this forum that they will only take on simple, quick installations where the pipework is already suitable.

Reed_Richards

Screwdriva said:

....The video should show that the Vaillant heat pump will cost quite a bit less to run compared to gas, assuming the house is reasonably insulted and the emitters are sized appropriately..... 

Actually, if the heat pump is fundamentally cheaper to run than gas for the same amount of heat, then the less well-insulated the house, the greater will be the savings!  You really don't need a well-insulated house to have a heat pump, you just need a well-insulated house so as not to have to spend so much on your heating.

slewis1972

ThanjsAlnat1 said:

Have you considered how suitable the current central heating system is to retrofit an ASHP? We found it's more complicated than we first thought.

We live in what sounds a very similar property (4 bed det. built 2003) and our gas CH system has microbore flexi pipes which are all hidden away behind the plasterboard and emerge, around 30cm above skirting height, behind each radiator. Beside needing larger radiators in most rooms we would also probably need to renew most of this pipework for an ASHP to work efficiently. This would also mean every room in the house would need some re-boarding and then redecorating. It may be that the house your buying was built in a similar way. If so, would you be happy with all the extra expense?

Octopus are running a great scheme but it's been mentioned by others on this forum that they will only take on simple, quick installations where the pipework is already suitable.

Thanks, just checked the virtual walkthrough of the house and yet, also got microbore flexi pipe -ahhhh..

Well, I wont be redpoing the pipes and where the radiators seems ample, this may put off ASHP. I suppose I wont know till they do a review.

As per message, iboost type solar diverter may actually be better if I choose solar and not have the battery as can then use the imersion to heat the cylinder in daytime. All bathrooms ( there are 3 ) use water hot water off the cylinder and are not electric.

But them, a battery maybe better on long term as can then use the battery to heat the imersion in early morning as longas topped up with solar or cheap energy in the night.

The gas boiler would then only be used for heating and potentially. Any excess power, would go back into the grid and help pay for gas I suspect.

Hmmmm

Bianchiintenso

ASHP can and do work perfectly well with microbore, we have no problem as do the people whose house we visited to see how their system coped before we took the plunge. We did have an issue for a while after the antifreeze was added to the system, which took a week to fully work around/mix as initially only half the radiator would get hot, but that soon sorted itself out. It can run without the antifreeze by using an antifreeze valve. Which is the preferred option to some people due to the lower viscosity and ease of pushing hot water round the system.
I agree with @Alnat1 though, a company like octopus might be reluctant to take on any job that involves microbore and will stick to the more standard installations 

Screwdriva

slewis1972 said:

Well, I wont be redpoing the pipes and where the radiators seems ample, this may put off ASHP. I suppose I wont know till they do a review.

As per message, iboost type solar diverter may actually be better if I choose solar and not have the battery as can then use the imersion to heat the cylinder in daytime. All bathrooms ( there are 3 ) use water hot water off the cylinder and are not electric.

But them, a battery maybe better on long term as can then use the battery to heat the imersion in early morning as longas topped up with solar or cheap energy in the night.

The gas boiler would then only be used for heating and potentially. Any excess power, would go back into the grid and help pay for gas I suspect.

Heat Pump: Octopus will not take on any house with piping under 15mm. They are working on a fix for this but it has yet to be deployed. Other installers may. I'd suggest checking with the Heat Geek assured program.

Diverter: A solar diverter (recommend Eddi over iBoost) is a good idea but it's still cheaper to heat via gas and sell excess to the grid instead. Still the right thing to do once prices are near parity.

Battery: The lack of a heat pump would mean your consumption would drop considerably, likely by 50% or more, making a battery a poor investment in terms of return (unlike rooftop solar or an investment in Ripple).

Boiler: If you do retain gas heating, a Viessmann 200-W boiler may save you a considerable amount of gas consumption (£). It has cut our consumption by approximately 50%, measured since last year

Alnat1

Screwdriva said:

Boiler: If you do retain gas heating, a Viessmann 200-W boiler may save you a considerable amount of gas consumption (£). It has cut our consumption by approximately 50%, measured since last year

I believe you went a bit further than just changing out the boiler and had an underfloor system installed in order to achieve that cut in consumption? I'm assuming @slewis1972 probably has solid floors downstairs and won't be considering that kind of upheaval.

IMO the property sounds perfect for solar but a 7 year old WB boiler shouldn't be too inefficient and is worth keeping for a few years. Might be worth doing the maths on a new HW tank and considering both a diverter and E7 or Octopus Flux/Go tariffs.

Screwdriva

Alnat1 said:

I believe you went a bit further than just changing out the boiler and had an underfloor system installed in order to achieve that cut in consumption? I'm assuming @slewis1972 probably has solid floors downstairs and won't be considering that kind of upheaval.

Our installation can be viewed here. 

If OP is considering a heat pump but cannot get one due to microbore, a Viessmann V200-W is controlled to modulate to incredibly low burn levels, to capitalize on larger emitter sizes and insulation, much like a heat pump does. It will deliver substantial savings over his old Worcester Bosch, as it continues to do for our property (forecasted annual savings for us are ~£1150, which is nearly the cost of the boiler itself)

slewis1972

I have emailed them to see about air source heat pump and microbore. As all new houses have microbore, I suspect there must be a workaround.
The flip side is, I may not then need a battery if I use a the decent gas boiler, and just use solar for electric + hot water cylinder and anything extra back into grid. Which may then help cover off any gas useage. 

Reed_Richards

ASHPs tend to be set up for s small temperature drop across the radiator, maybe 5 degrees instead of the 20 degrees of a conventional heating system.  The only reason for this I can see is that it maintains a higher average radiator temperature, so the radiator does not need to be as big.  To achieve this the flow rate for the water circulating through the radiators has to be higher than in a conventional heating system.  The issue with microbore pipes is that they might not be able to sustain a high flow rate, particularly if they are already a bit gunged up.