Are new domestic renewable projects worth doing these days?

[Highland Mule]

Not a huge user of elecric power, so would probably export most of what a PV system would produce. Have previously thought about a small scale turbine but (fortunately, I think, given manufacturer went bust), didn't follow through at the time.

Are there any options that would make financial sense for a new project on to an old house, or am I better spending my money on enhancing the insulation? Wondered about PV linked to a thermal store to give me heating and hot water.

Currently, farmhouse has oil boiler on timer and log stove which also heats water when we light it (winter, evenings mostly). Typical consumption around 2,000 litres of oil a year plus maybe three or four tonne of (home harvested) logs. Roof pitch is mostly E/W.

Would be nice if any new project gave a few £ back in some way, or at least made a decent dent in the bills.

 

[Eocycle - Dan]

Hard to say for sure without knowing the specifics but in general yes, they are. E/W for solar can actually be a good thing now the focus is on self consumption. You get a much more usable delivery of power throughout the day, but it does not make any sense, financially or otherwise, to export to the grid. Batteries can help, but if you don't use that much electricity, it is probably not worth it. A thermal store linked to the PV works well too although bear in mind you get no night time solar contribution and very little any time of the day between November and February. Any form of heating, renewable or not, is most efficient in a well insulated home and in my experience farm houses rarely are, so my advice would be to start there. Maybe get a small solar system optimised for self consumption, with as close to 0% exported as possible. Speak to 2 or 3 well established local(ish) companies and compare notes.

 

[Highland Mule]

Thanks Dan. Trouble is consumption can be zero for days at a time and then be a chunk for a few - there’s no regular theme to it and rarely any in daylight.

What’s the rough costing for a small solar these days, say 4kW on a roof?

 

[Eocycle - Dan]

I would guess between £4.5k & £7k depending on equipment and other costs although I've been out of the solar game for a little while tbh. Sounds like you may be better off trying to find an alternative (and cleaner) solution to your oil heating, a woodchip boiler could work well since you already have access to some of the fuel. Capital costs are higher but there are still goverment incentives (RHI). Speak to these guys https://www.zerowastescotland.org.uk/ they can advise you and even arrange funding for some measures.

 

[f0ster]

with solar you can make use of most of the generated power by fitting an iboost, it has a clamp that goes around the incoming meter tails and if any elec is going to be exported if switches on the immersion heater for hot water, there by saving you heating the water by oil boiler etc, the iboost will not pull and power in from the grid no matter what power you are generating, even only a couple of hundred watts is made use of, you can also over ride it by a press of a button to give an hour etc etc.

 

[Dave645]

Thanks Dan. Trouble is consumption can be zero for days at a time and then be a chunk for a few - there’s no regular theme to it and rarely any in daylight.

What’s the rough costing for a small solar these days, say 4kW on a roof?

I had a 10 kw solar electric system priced at £8.7k fitted. Payments for exported electric are only 3-4p so it’s still 14 years to get paid back even with 50% self consumption. So for me that’s was a no.

But my advise to you would be insulate, that’s always going to cut bills more than solar when your heating needs 2000liters of oil plus wood.
first windows if not double already then skip double and go triple the green homes grant can help.

Then your walls, Internally, or externally if you have no cavity.
roof if not already well done may not meet new standards if done more than 20 years ago.

Look at this link.

https://icax.co.uk/Green_Homes_Grant.html
Take advise What will help you best cut your reliance on oil.
Ground source heat pumps still get grants, but I would only do that after you see how the insulation upgrades goes.
you may be happier to have an upgraded wood burner, that runs more than just hot water. And you may find that the new more efficient wood stoves can heat your home within that 4t your already using.
For one a room sealed wood burning stove, that has its own air supply will cut drafts and improve room temps just from the fact it’s room sealed.


https://www.stovesonline.co.uk/central_heating_wood_stove.html


https://www.stovesonline.co.uk/stoves/wood burning/Woodfire Stoves/all_styles/boiler

https://www.stovesonline.co.uk/external-air-stove.html

I used this company for my stove, but take advice from anywhere you wish.

 

[Highland Mule]

Thanks, I think that a concerted effort to get better insulation into the house would be a good idea for a start. Is 2000litres a year a lot to heat a 4 bed farmhouse? I didn't think it was too bad at all.

The stove has a decent size and usually only lit at weekends, so perhaps 4 tonne is an exaggeration - certainly would be 2 or 3 though, I'd guess. From memory it throws about 3 or 4 kW to the room and around 8-10 kW into the water system. Via a Dunsley neutraliser, we get a tank of piping hot water and then the rest goes to the radiators.

Windows are all double glazed modern units, draughts could be better tackled but we like some fresh air in too. Walls are 3' stone so really only a bit of cavity inside as an option I guess, loft could probably benefit from a tidy up wher the various trades have been in and not placed insulation back properly thereafter.

This weekend, loft it is.

 

[br jones]

Thanks, I think that a concerted effort to get better insulation into the house would be a good idea for a start. Is 2000litres a year a lot to heat a 4 bed farmhouse? I didn't think it was too bad at all.

The stove has a decent size and usually only lit at weekends, so perhaps 4 tonne is an exaggeration - certainly would be 2 or 3 though, I'd guess. From memory it throws about 3 or 4 kW to the room and around 8-10 kW into the water system. Via a Dunsley neutraliser, we get a tank of piping hot water and then the rest goes to the radiators.

Windows are all double glazed modern units, draughts could be better tackled but we like some fresh air in too. Walls are 3' stone so really only a bit of cavity inside as an option I guess, loft could probably benefit from a tidy up wher the various trades have been in and not placed insulation back properly thereafter.

This weekend, loft it is.

Put it this way i built a 4 bed house a few years ago ,uses 300 to 400l of lpg a year at 30 p ish per litre
So insulation is everything

 

[Dave6170]

Sounds pretty good. My house is 4 years old 170m2 and we use 1800l oil a year. Boiler does everything. Have a wood burner with a back boiler aswell, should use it more.
Wish I put the panels on the roof that heat the water when we built it.
I'd say avoid pellet boilers.

 

[br jones]

Sounds pretty good. My house is 4 years old 170m2 and we use 1800l oil a year. Boiler does everything. Have a wood burner with a back boiler aswell, should use it more.
Wish I put the panels on the roof that heat the water when we built it.
I'd say avoid pellet boilers.

7 grands worth of insulation ,it does work,and attention to the drafts

 

[Dave6170]

7 grands worth of insulation ,it does work,and attention to the drafts

My house was too airtight for the test when we were getting it passed.

 

[Highland Mule]

Sounds pretty good. My house is 4 years old 170m2 and we use 1800l oil a year. Boiler does everything. Have a wood burner with a back boiler aswell, should use it more.
Wish I put the panels on the roof that heat the water when we built it.
I'd say avoid pellet boilers.

4 years? Mine predates The Act of Union.

 

[Dave6170]

4 years? Mine predates The Act of Union.

Yeah I just mean 2000l sounds OK for an old house. My mother in law has a big old house and must use double that

 

[renewablejohn]

Totally renewable here with an old farmhouse going back to approx 1650. As others have said insulation and elimination of draughts is key.

 

[Dave645]

Thanks, I think that a concerted effort to get better insulation into the house would be a good idea for a start. Is 2000litres a year a lot to heat a 4 bed farmhouse? I didn't think it was too bad at all.

The stove has a decent size and usually only lit at weekends, so perhaps 4 tonne is an exaggeration - certainly would be 2 or 3 though, I'd guess. From memory it throws about 3 or 4 kW to the room and around 8-10 kW into the water system. Via a Dunsley neutraliser, we get a tank of piping hot water and then the rest goes to the radiators.

Windows are all double glazed modern units, draughts could be better tackled but we like some fresh air in too. Walls are 3' stone so really only a bit of cavity inside as an option I guess, loft could probably benefit from a tidy up wher the various trades have been in and not placed insulation back properly thereafter.

This weekend, loft it is.

2000 litres is not terrible, but it is still 2000 litres of oil, moving to 100% wood and no oil would be better, not just for your pocket.
fresh air is important to stop damp.
a sealed stove will help Remove the negative air pressure unvented stoves create, they normal require direct room vents or if under 5kw rely on drafts, room sealed stoves that have there own vent that draws air directly into the stove from outside, eliminate the drafts and the need for a permanent vent for stoves over 5kw.

after insulation I would look at heat recovery ventilation I imagine it wouldn’t be that hard for houses with un used lofts to do the rooms below the loft space, the difficult bit comes for ground floors as the ducting can be big.
https://www.bpcventilation.com/heat-recovery/full-diy
Kits are not bad
https://www.zehnder.co.uk/products-...-indoor-ventilation/heat-recovery-ventilation
I used a zehnder unit. And I know Zehnder do flat tubing for retro fitting.
But these systems go hand in hand with basic air tightness of your home, there is no point fittting heat recovery if your not going to make an effort to make the house air tight.. like using room sealed stoves etc.

 

[renewablejohn]

2000 litres is not terrible, but it is still 2000 litres of oil, moving to 100% wood and no oil would be better, not just for your pocket.
fresh air is important to stop damp.
a sealed stove will help Remove the negative air pressure unvented stoves create, they normal require direct room vents or if under 5kw rely on drafts, room sealed stoves that have there own vent that draws air directly into the stove from outside, eliminate the drafts and the need for a permanent vent for stoves over 5kw.

after insulation I would look at heat recovery ventilation I imagine it wouldn’t be that hard for houses with un used lofts to do the rooms below the loft space, the difficult bit comes for ground floors as the ducting can be big.
https://www.bpcventilation.com/heat-recovery/full-diy
Kits are not bad
https://www.zehnder.co.uk/products-...-indoor-ventilation/heat-recovery-ventilation
I used a zehnder unit. And I know Zehnder do flat tubing for retro fitting.
But these systems go hand in hand with basic air tightness of your home, there is no point fittting heat recovery if your not going to make an effort to make the house air tight.. like using room sealed stoves etc.

I have Partel Heat recovery units which are very good as they work in tandem so as one pushes air in the other is extracting. Only difficulty installing was cutting a 100mm hole throgh 3ft thick stone walls with stone rubble infill. Also agree in respect of external air supply of stoves which made a big difference as we had to do that when the 3g windows and swedish doors were installed as the normal draughts which would normally feed the fire had been eliminated.