My Plan to Achieve Energy Freedom - The Road to Zero Energy Bills

iainBB · 05-09-2016 10:10am

Great post, thank you,

What retail price are you getting per watt the lowest I can find is 1.1 euro per watt with shipping which for me is still not a good Return on investment (ROI).

rolion · 05-09-2016 11:08pm

Conor20 wrote: »

Solar PV now makes financial sense in Ireland.

Time to generate my own power
Statistically (I guess), half of the houses in Ireland have a rear facing roof to the South or East. These houses can mostly just go ahead and install solar without any planning considerations. I am not one of these! The front of my house faces South, but there is an exemption from needing planning permission for a Solar PV array up to 12M^2 on the front of houses in Ireland. So that's a good start. With this, I can fit 7 Solar PV panels without planning permission. In the UK, when a Solar Feed in Tariff was introduced to encourage people to install Solar PV, the need for planning permission for any domestic system was removed. If that happens in Ireland, I can add further panels at that point. But that might be a while, and from an initial few quotes I've gotten from PV companies for the setup above, I'm seeing a return on investment of about 7.5% all things considered, so we're now passed the crucial ROI figure of paying down our mortgage (3.75%). The price of solar has fallen to a point where it is a better investment of my previous energy savings than paying down the mortgage or any other investment available (bank interest rates are ~1%, stock market perhaps 4-5% with high risk). As a logical investor - I will now install Solar PV.

@Conor20

With all due respect Conor...thats a lot of copy and paste bs with capital B and capital S !!!

For a proper PV system to offset and do any kind of return to its owner,you will need minimum 8 panels x 250W each.Then an inverter for 2.5Kw generated power,installation kit,new dual feed electrical meter and not lastly,the rip-off charge of the installer(s).
I will say as cost at minimum €5,000 ex VAT.

If you do 10 units per day at .15c each,is €1.50 per day,€45 per month,€90 per bill + additional PSO and taxes,around €150 per bill.

In a good day and not like we had his fcuking weather lately,you can generate maxim 3-5 unit per day,from May to October. All the other days of the month, possible 1-3 units,just to keep inverter warm.

Now,please do the maths...

Im talking from years of doing the maths and now,waiting for the past 2 months with the panels in my living room because i cannot find someone to install it for me, unless i pay from €1.500. Again,do the maths...where are the fcuking savings !?? Most of the suppliers wants to sale at a cost that will attract you then kick you at installation.

IF i had to start again,i will not chose any type of fcuking renewables,as a DIY job.Not worth it,life is too short ! Someone(s) are destroying this planet right now so please i cannot take the carbon tax savings any more !
Have fun...

iainBB · 06-09-2016 6:11am

Something was just not right with that post. It was like an advert. You saw right through it.

I am looking into this for heating water only with a simple setup ,

The most expensive thing to do in your house is heat water,

250 watt panels X 8
12 battery
12 volt heating element put in tank.
Controller

At less then a euro a watt it is getting close to this setup work with good ROI.

air · 06-09-2016 8:02am

iainBB wrote: »

Something was just not right with that post. It was like an advert. You saw right through it.

I am looking into this for heating water only with a simple setup ,

The most expensive thing to do in your house is heat water,

250 watt panels X 8
12 battery
12 volt heating element put in tank.
Controller

At less then a euro a watt it is getting close to this setup work with good ROI.

If you're looking to heat water then heat the water, batteries make little or no sense.
Just install the panels on grid as normal and use a PV diverter to divert to a normal 230V immersion element.
The ROI will be higher this way as you will offset your consumption at the full retail value of the energy fed back to your supply.

Rolion, where are you located and do you have a slate or tiled roof?
Would you not consider installing them yourself, it's not all that difficult.

On ROI, I have a 4kW system (soon to be expanded).
It is oriented 1500W South and 2500W West roughly.
It generated €200 in it's first year in FIT payment from Electric Ireland and would have offset probably another €100 in self consumption.
Ballpark exported 2000kWh, imported 1000kWh, obviously self consumed the remainder of production.
Total annual bill about €250.

So essentially the FIT offsets all my consumption costs but I'm still paying the standing charges / PSO levy etc.

My total cost will be around €600/kW installed, however I did all the work myself and sourced everything in the UK using eBay etc extensively.

iainBB · 06-09-2016 8:59am

air wrote: »

If you're looking to heat water then heat the water, batteries make little or no sense.
Just install the panels on grid as normal and use a PV diverter to divert to a normal 230V immersion element.
The ROI will be higher this way as you will offset your consumption at the full retail value of the energy fed back to your supply.

I still like to keep it simple for maintenance and ROI, why convert back to AC with both cost and power loss for no reason. you can buy a 12 volt DC element for next to nothing add it to your hot water system or underfloor heating tank.

We have enough room for 4M X 3M area about 2KW in size.

air · 06-09-2016 9:41am

iainBB wrote: »

I still like to keep it simple for maintenance and ROI, why convert back to AC with both cost and power loss for no reason. you can buy a 12 volt DC element for next to nothing add it to your hot water system or underfloor heating tank.

We have enough room for 4M X 3M area about 2KW in size.

If you do a bit of research you'll find that what you propose won't work at all really.
1. 2000W @ 12v is going to be over 150A.
The cable required if the PV is any distance at all from the tank will be colossal.
2. The PV won't work at its maximum power point if it's direct connected to the element and the majority of the time will produce nothing at all.
3. A tank provides storage in thermal form, what's the point in adding expensive and short lived batteries to the equation.
4. You convert back to AC so you can use the panels to create high value AC electricity instead of low value heat.

iainBB · 06-09-2016 10:58am

wow interesting, thank you

Conor20 · 06-09-2016 1:18pm

rolion wrote: »

@Conor20: With all due respect Conor...thats a lot of copy and paste bs with capital B and capital S !!!.. Now,please do the maths... Im talking from years of doing the maths and now,waiting for the past 2 months with the panels in my living room because i cannot find someone to install it for me, unless i pay from €1.500.

I feel like we're going in two different directions here - a DIY project versus a fully installed and warrantied installation, which is what I'm looking for. All I do is maths. I want to have little or no uncertainly for my investment. I've used freely available software to predict how much a solar PV setup will generate on my roof. I've gotten quotes for that setup from Solar PV suppliers. I calculate that the system will save more money than it costs over it's warrantied lifetime. As a result I will have it installed and then measure the results.

iainBB wrote: »

Great post, thank you. What retail price are you getting per watt the lowest I can find is 1.1 euro per watt with shipping which for me is still not a good Return on investment (ROI).

Calculating the €/kWh rather than the €/watt potential makes more sense to me, so the investment can be normalised back to the money the PV array will generate over it's lifetime - What it generates is more important to me that what it's potential is. To get that, I use the prediction software to predict the yearly yield of the PV setup based on the sunshine records of my area, and extrapolate that over the 25 year performance warranty of the system. That gives me a predicted number of kWh generated over it's lifetime (say, 47,500kWh for a 2kWp system over 25 years). I know how much the system costs (say, €4,500 now plus €1,000 for an inverter replacement down the road = €5,500 in total), which would give €5,500 / 47,500kWh = €0.11 per kWh. Our day rate is currently about €0.18 / kWh including VAT, Carbon Charge and PSO. It'll likely go up in the future. These are all just illustrative for now, but that's the idea. I've been watching that €/kWh for a while, and I finally feel it's at the point where I'm happy to install a PV array. I'm not going to hang about, I'll hopefully get it installed over the 1-2 months before the Home Renovation Scheme VAT Refund expires, and will have some initial generation results in 6 months or so.

pwurple · 06-09-2016 9:22pm

What is your usage pattern ConorB?

For me, PV does not make sense just yet, because my higher usage is at night (i charge my car, like you do, and run my appliances at night, on a night rate of 0.07). Winter evenings also, lights come on, oven goes on, tv goes on when we get home. Summer evenings we are outside bbqing and running about more. Daytime, I'm at work.

Without either energy storage or selling to the grid, i feel that I would be generating electricity in a domestic environment at a time that is pretty much inverse to our usage pattern.

Conor20 · 24-10-2016 2:04pm

It's been 18 months since this project started and it's a pretty good time to check in on progress so far. The aim is to get to zero energy costs, so if they're measurably less than they were, then that's progress. If you remember from my first post, I think the first step to reducing something is measuring it, so I've been measuring our bills in Electricity, Heating and Transport on the same day every month since then - not waiting for bills which are often estimated, but reading the meters on the last day of each month and recording the values so I can compare them over time. I've compiled and charted the data up to March 2016 (took 15 -20 minutes in Excel) and the picture is good. When I started measuring monthly energy costs in January 2014, our yearly total cost was 2,725.22 per year. As of March 2016, it was 745.92 per year. We're now saving 1,979 a year from where we were.

When I look at a chart of our monthly energy costs over that period, the impact of the investments are easy to see:

Another way of looking at our energy costs with each component highlighted (electricity, heating, transport):

Switching to an electric car took a huge chunk out of our transport costs. It went from costing 246 per month (petrol, tax) down to 24 (electricity). It has been nice having 222 extra in our pockets each month after that. Adding the wood burning stove has also clearly eaten into our gas costs each month. We pay 0.06 per kWh for gas, and about 0.01 per kWh for wood, so each night that the wood burning stove is on and heating the house, we're saving 83% of the cost of heating the house that night. The reduction is pretty clear when comparing March 2015 with March 2016. Switching all of our light bulbs to LEDs is saving 87.29 per year, which is why our electricity bill hasn't increased much when we switch to the electric car, even though it also includes all of our transport costs now too.

Just like when I started this project, at any time, I want to identify the next best investment to make which will save more money than it costs. For this, it makes sense to compare where my money is going on energy (then and now):

January 2014:

By March 2015, we had eaten into the transport costs by replacing our petrol car with an electric car. The total energy spend run rate was 2,056.75:

By March 2016, our total energy spend run rate was 745.92:

Heating and Transport energy costs are way down. Looking at this chart, It's obvious that our electricity costs are the next target. I believe Solar PV will be the answer to this, to attempt to bring this cost down towards zero. When I started investing in these energy saving projects, I started a direct debit to send the savings our of our current account to a savings account to avoid just flittering away the savings. I increased the Direct Debit each time we invested in a new project - the LEDs, heat reflectors, the wood stove with back boiler and the electric car. That account stands at a few thousand euro now, and it'll be very satisfying to use that to install a Solar PV to eat into our electricity bill.

All in all, progress has been fantastic. Saving 2,000 per year is considerable - given a marginal tax rate of 51% in Ireland, it's the same as getting a raise of roughly 4,100 per year in work. This money has been stacking up to invest in further energy investments, and once our energy costs are down to zero, it's going to stack up in a retirement fund pretty quickly. Also, as of May 2016, the energy savings had resulted in 8,170kg of CO2 not being released into the atmosphere. Eight Tonnes! It shows how a little effort can yield pretty decent results. Most of the investments have also increased our quality of life too - the electric car is both more powerful and much nicer to drive than the previous petrol car, the wood burning stove has literally brought the family together in winter evenings, the energy monitor in the kitchen gives us something to talk about and is a great educational tool for my son for both energy and finance. I'm guessing that the first bit of savings were relatively easy and that getting down to near zero from here will be a lot harder, but nevertheless, this is progress. 2000 a year down, about 800 to go.

Ronan Raver77 · 15-12-2016 8:40pm

Great post and very interesting indeed.:)

Calahonda52 · 15-12-2016 11:11pm

Good project here, congratulations for taking it on and sharing.

I know this is being done on a cash accounting basis but bear with me.

Few questions, if I may:
Can you share the math on the car from 246 down to 24, your post is silent on the cost per kWh for elec.
I presume you are still charging for free wherever you can and not at home?

How are you arriving at wood costing 0.01/ kWh?
The SEAI see it differently
http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/Domestic-Fuel-Cost-Comparisons.pdf

Does it include any opportunity cost for the time spent "organising" fuel/ash/etc/etc when compared to gas.
The other point is the differential between the efficiency of the stove versus the gas boiler.

If gas is 6 and the efficiency is 80% then the cost per kWh is 7.5

If the wood is 7.5 as per SEAI and efficiency is 55% then the wood is 13.6

Thanks

Conor20 · 21-12-2016 2:43pm

Calahonda52 wrote: »

Good project here, congratulations for taking it on and sharing.

No problem. Thanks!

Calahonda52 wrote: »

I know this is being done on a cash accounting basis but bear with me.
Can you share the math on the car from 246 down to 24, your post is silent on the cost per kWh for elec.
I presume you are still charging for free wherever you can and not at home?

Sure. I added up all of the costs associated with the running of our petrol car, and an electric car over a year. The petrol car consumed 105.6 litres of petrol per month doing about 300km per week, which came to €2030.56 per year. Maintenance of the petrol car had averaged €1100 per year over the three previous years. Motor tax was €570 per year. On the other side of things: Motor tax on the electric car dropped to €120 per year. The electric car consumes 48kWh per 300km and I charge it at home at night for 7 cent per kWh. So it costs €3.36 per week, or €3.38 * 52 = €175.76 per year versus €2030.56 per year for the petrol car. The electric car has had one service in the two years I've had it so far. The only item listed on the itemised bill was changing of the pollen filter, so I expect maintenance to be quite a bit less. I factor in a replacement of the battery after 5 years into the costs of the electric car. I hope to reuse that battery to store power for our house, though I assume no value in the financial calculations. With all of the costs of both cars totted up, the petrol car cost €3250.56 a year to run, and the electric car costs €295.76 a year to run. That's €270 a month, and €24 a month respectively, which is where the €246 saving a month you mention comes from. The car resulted in a yearly saving of €2954.8, which translates to a 4.1% return on investment of the purchase price of the electric car assuming zero resale value at year 10. That's higher than our mortgage rate, so it made sense to replace our car with an electric car rather than pay down the mortgage. Hence, we bought an electric car. We haven't looked back. There have been many additional benefits in addition to the money - nicer drive, more powerful acceleration, no fumes, in-car technology, etc.

Calahonda52;101982423
How are you arriving at wood costing 0.01/ kWh?
The SEAI see it differently
http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/Domestic-Fuel-Cost-Comparisons.pdf
Does it include any opportunity cost for the time spent "organising" fuel/ash/etc/etc when compared to gas.The other point is the differential between the efficiency of the stove versus the gas boiler. If gas is 6 and the efficiency is 80% then the cost per kWh is 7.5. If the wood is 7.5 as per SEAI and efficiency is 55% then the wood is 13.6

Firstly, before talking about wood: in the long term, I will install a Heat Pump to heat the house. So if you have the money available, you should skip wood and go straight to a heat pump. It will be the cheapest way to heat your house in the long term compared to gas, oil or wood, particularly when coupled with Solar PV.

Now to answer your question about how I can access wood so cheaply. This will take a post in itself to explain fully, which I have in the works - I prefer to only write a post once I have measured the actual results, rather than predicting them. But in short: I planted trees for firewood, and do the cutting and splitting myself. I don't attribute a cost to the time I spend cutting and splitting because I love doing it. Also, coupled with cycling around the place, it removes the need to pay for a gym and (provided I don't hit myself with an axe at some point!) it will reduce health costs in the future - anything that avoids obesity/diabetes/lifestyle induced health issues seems to save a lot of money in later life. The only cost involved is the transport of the wood, which I do with a few trips in the electric car each year. That comes to €0.01 per kWh. I did a "fun" (I certainly told him it was fun!) experiment to teach my son about energy content to figure this out. (1) Weigh an average log of wood - 800 grams - see attached photo (2) Count the number of logs that go into a fire in one evening - about 12 (3) Multiply the weight of the 12 logs - about 10kg - by the kWh content per kg of wood - 4kWh per kg for dry logs - by the stove efficiency - about 80%. That gives 10kg * 4 kWh / kg * 80% efficiency = 32 kWh per 10kg of wood transported. The trip with 150kg of wood hence transports about 600 kWh of heat energy to the house. That drive costs about €6 (Charging the electric car = €1.68, Buying coffee = about €4), hence 600 kWh / €6 (which is 600 cent) equals €0.01 per kWh of heat delivered to the house.

By the time I've lost the ability to cut and split wood myself, we will have switched to heating the house with Solar PV + a Heat Pump which I believe will be by far the most cost effective method of heating a house.

Calahonda52 · 21-12-2016 4:46pm

Good stuff again, thank you!

I asked the questions so as others could benefit as well.

I suspect with the e car that you don't do too many long journeys, so charging at night at home works for you and you don't have any battery recharge syndrome ( or whatever it is called) .

Whats the theoretical range of the e car?

Re the wood pricing, for the ordinary bloke, this financing model is not applicable so my concern here is that folk would pile into wood as they saw on the www that it was 0.01 euro a kWh.

What make is the stove that gives 80% efficiency?

pwurple · 21-12-2016 10:55pm

Various models of cars have different ranges on a full charge. I have a 2015 leaf, range is theoretical 150km. Newer models have 250+ range.

What helped me though was that my android phone logs my location history with google history. I was able to look at my maximum journey lengths over a year. At no time had I exceeded that range.

22-12-2016 12:19am

Calahonda52 wrote: »

recharge syndrome ( or whatever it is called) .

Range anxiety methinks.

Conor20 · 24-12-2016 11:28pm

Calahonda52 wrote: »

Good stuff again, thank you! I asked the questions so as others could benefit as well.

I suspect with the e car that you don't do too many long journeys, so charging at night at home works for you and you don't have any battery recharge syndrome ( or whatever it is called). Whats the theoretical range of the e car?

Sir Liamalot wrote: »

Range anxiety methinks.

Nissan quote 150km of range for the 2014 Leaf, which is what I have. If you accelerate and brake hard, it'll be more like 120km. Conversely, I've gotten 170km driving it consistently at 70-80kmph on back roads, so about 130-155km is the range you end up with. The 2016 Leaf (30kWh) is stated at around 200-250km, and the 2017 is rumored to have a 60kWh battery, which would suggest a 400-500km range if true. 150km of range has been fine for us. Like most people, most of our driving is commuting or driving around the city. For any two car household, switching one to a second hand electric car would save a considerable amount in running costs. We have just one car, the Leaf, and it's worked fine for us, including longer drives using the public charging network across Ireland.
Range anxiety is just not an issue when you actually start driving an electric car. My best guess is that the media needed something to say about electric cars other than "it's just like driving an internal combustion engine car, but cheaper" and that's where the phrase came from. The car tells you exactly how much battery is left, and how far it will go on it's current charge. You (presumably) know where you are going and how far it is away - so you know before you leave whether you can get there on a given charge or not. While some people have experienced the teething problems with the public charging network for inter-city driving, you can now see in real-time whether charge points are down or occupied, so you can anticipate most problems in advance and plan accordingly. Also - while the faster charging cables come as standard, you can also buy a three pin plug cable for the car. Meaning if worst comes to worse, you can literally be within 250m of a "petrol station" most anywhere in the entire country. But that will probably never happen - get a lend or a test drive of an electric car and try it for yourself. All of the pre-conceptions will disappear within a few days.

Calahonda52 wrote: »

Re: the wood pricing, for the ordinary bloke, this financing model is not applicable so my concern here is that folk would pile into wood as they saw on the www that it was 0.01 euro a kWh. . What make is the stove that gives 80% efficiency?

The stove is a Boru 600i - efficiency is stated (by the manufacturer, it must be said) @ 78.8%.
Agreed. For almost everyone, a heat pump will be the cheapest way to heat a house, ahead of wood, gas and oil. A small number may be have the time and space to plant trees like I did, but in the long term, I think a heat pump + Solar PV will beat even the heat energy €/kWh achievable from self-grown firewood.

2Shae · 02-01-2017 6:22pm

I am really interested in how you plan to install the heat pump.

My family house was built in 2007 and is well insulated and all of the hot water comes from burning turf in the stove. we have no electric showers (pump showers using the hot water from the stove).

We had an oil burner installed in the shed and insulated pipes going between the house and the shed but it has never been comissioned. I really like the idea of putting the heat pump in instead and giving them the option of using the heat pump to supplement the stove.

rolion · 03-01-2017 3:28pm

@Conor

I will realy appreciate some magic that you do with numbers and graphs and formulaes..
Can you do a "thing" comparing gas boilers VS heat pumps,please !?
With and without the PV panels.

Thanks

loyatemu · 04-01-2017 5:12pm

a lot of great stuff in this thread - thanks for all the work Conor.

a few things that strike me though - changing from gas to wood only makes sense if you have a free supply of wood, and from an environmental perspective I'm not convinced it's any better.

I'm not sure that a heat pump will offer any great savings over gas either, unless you can run it off PV. My electricity unit rate is a little over 3 times my gas unit rate, so if your heat pump is 300% efficient or better (and other threads on here suggest 300 - 350 is realistic), you'll make some small saving, but not much and you'll have to factor in the cost of the pump and installation.

Looking at my gas consumption (for heat, water and cooking) I think I could save ~130 per annum by switching to a heatpump but only if I cancelled my gas account completely. At 3K for heat pump and installation that's a 23 year payback period which isn't great. Adding solar tubes to the mix might improved that but I still don't think it would be worth doing.

Also - and this is obviously going to be a subjective - has the radiator foil made any difference? I've seen it dismissed elsewhere as largely pointless, as radiators work by convection rather than radiation.

rolion · 04-01-2017 7:27pm

loyatemu wrote: »

I'm not sure that a heat pump will offer any great savings over gas either, unless you can run it off PV. My electricity unit rate is a little over 3 times my gas unit rate, so if your heat pump is 300% efficient or better (and other threads on here suggest 300 - 350 is realistic), you'll make some small saving, but not much and you'll have to factor in the cost of the pump and installation.

That's what bothers me too...I have PV panels and a good gas boiler. I can do most of the works as diy. PVs works fine when god Sun is out there .

If I apply your maths and switch off the gas and migrating to electricity... what about the winter and the night times WHEN the demand is higher than day time or sunny summers when PVs works !?? Not so good with all those numbers and COPs and so on. Probable Heat Pump is better when gas supply is not available ,with or without PV panels at all.

loyatemu · 05-01-2017 12:53am

rolion wrote: »

That's what bothers me too...I have PV panels and a good gas boiler. I can do most of the works as diy. PVs works fine when god Sun is out there .

If I apply your maths and switch off the gas and migrating to electricity... what about the winter and the night times WHEN the demand is higher than day time or sunny summers when PVs works !?? Not so good with all those numbers and COPs and so on. Probable Heat Pump is better when gas supply is not available ,with or without PV panels at all.

I've seen them marketed as "ideal for properties that are off the gas network" - i.e. they're cheaper than oil or solid fuel options. Geothermal pumps may be a bit more efficient than air pumps.

gooner99 · 05-01-2017 2:22pm

I would imagine that piped natural gas is the cheapest way to heat your house, unless you have free fuel supply (turf/wood). LPG in a tank would be a different story.

pjogorman · 11-01-2017 6:05pm

Hi all,
I've been reading this thread a while now and I think it is great.

I currently am trying to get to energy freedom. I took my first step and picked up a Nissan leaf 30kw 6.6kw charge.

I am moving to night rate esb to install for free next week and I will be changing my supplier.

I am looking at this from Nissan https://electrek.co/2016/05/11/nissan-vehicle-to-grid-enel-uk/ the enel vehicle to grid (v2g).

As I have the 30kw battery and only travel 36km round trip I have excess battery capacity.

So what I am looking at is getting the tesla 14kw powerwall2 and plug my car in when I get home.

Obviously the only way this would work is if you can get a full charge in work.

Eventually look to go from piped gas to electric to heat house and water.

Any thoughts?

loyatemu · 11-01-2017 6:25pm

there's a big discussion on the powerwall elsewhere on boards and the figures don't seem to add up - even if you are charging it from solar PV only, it's still substantially more expensive per kWh than taking your power from the grid.

rolion · 11-01-2017 9:44pm

Tesla is a great solution for "tomorrow", "today" is too expansive as RoI numbers !

Also,im not aware of anything except gas that is more cost effective to heat a house.

Rgds

zulutango · 12-01-2017 1:02pm

rolion wrote: »

Tesla is a great solution for "tomorrow", "today" is too expansive as RoI numbers !

Also,im not aware of anything except gas that is more cost effective to heat a house.

Rgds

It really depends. If your house is so well designed and built, such that the heat losses are very small, then electricity starts to make sense because of the very low capital cost of electric heating systems versus a plumbed gas heating system.

air · 12-01-2017 1:38pm

pjogorman wrote: »

So what I am looking at is getting the tesla 14kw powerwall2 and plug my car in when I get home.

Obviously the only way this would work is if you can get a full charge in work.

Eventually look to go from piped gas to electric to heat house and water.

Any thoughts?

So you bought a car with a bigger battery than you need in the hope of recharging it at work at your employers expense in the hope of then using the energy stored in the car battery to recharge a battery in your home?

Have you run this masterplan past your employer at all?

josip · 12-01-2017 1:41pm

air wrote: »

So you bought a car with a bigger battery than you need in the hope of recharging it at work at your employers expense in the hope of then using the energy stored in the car battery to recharge a battery in your home?

Have you run this masterplan past your employer at all?

The employer won't be too worried.
PJ will be in working every day over the winter, even over Christmas, to keep the house heated.

Conor20 · 01-02-2017 1:08pm

loyatemu wrote: »

Also - and this is obviously going to be a subjective - has the radiator foil made any difference? I've seen it dismissed elsewhere as largely pointless, as radiators work by convection rather than radiation.

Yes, I believe it has. You're right in that most of the heat we feel from radiators are from convection heating of the air around the radiator than the radiation it gives off. Everything above absolute zero gives off radiation, the hotter something is the more radiation it gives off and this radiation heats things it hits, so it definitely makes some difference in terms of reflecting that radiation back from the wall. Whether this difference is meaningful in terms of heating the house is the question. I do actually have a plan to try to measure this scientifically, by training an infrared camara on the house to see how much heat is escaping from areas covered and not covered by heat reflectors. Along these lines:

These guys quote a 20% saving a year off heating costs based on academic research from Queen's University in Belfast, among others. But of course they could be selectively quoting in order to sell. So my conclusion thus far is that they do make some difference, and given they also result in subconscious queues when you see them ("Maybe I'll just put on a jumper rather than spending €10 a day keeping the heating at 25C so I can wear a tee-shirt and shorts in January"), I think they are worth doing. Infrared analysis will confirm or disprove this when I get a chance to do it.

pjogorman wrote: »

I am looking at this from Nissan https://electrek.co/2016/05/11/nissan-vehicle-to-grid-enel-uk/ the enel vehicle to grid (v2g). As I have the 30kw battery and only travel 36km round trip I have excess battery capacity. So what I am looking at is getting the tesla 14kw powerwall2 and plug my car in when I get home.

air wrote: »

[In response to quote above] So you bought a car with a bigger battery than you need in the hope of recharging it at work at your employers expense in the hope of then using the energy stored in the car battery to recharge a battery in your home?

I actually think this isn't as crazy as it sounds. An electric car has a big battery, and big batteries can be used to power anything. Lots of utilities are already looking at how they could pay EV owners money to access some percentage (say, 20%) of the battery while it's plugged in to the house to power the grid en-masse as a way to ensure grid stability and remove more expensive power plants. So I'm not about using as a way to siphon off electricity from my employer (!) but if I try to get to PV + Batteries, and disconnect from the grid entirely, the electric car is basically the backup plan if there is no sun for a few days - drive it to a nearby charger, charge it and plug it back into the house to power the house / charge on site batteries. New EVs are coming with 30-80kWh batteries. A house consumed maybe 10-20kWh a day, so the car could conceivably power the house for several days with this setup.

2Shae wrote: »

I am really interested in how you plan to install the heat pump. My family house was built in 2007 and is well insulated and all of the hot water comes from burning turf in the stove. we have no electric showers (pump showers using the hot water from the stove).

We had an oil burner installed in the shed and insulated pipes going between the house and the shed but it has never been commissioned. I really like the idea of putting the heat pump in instead and giving them the option of using the heat pump to supplement the stove.

Yep, certainly sounds like you're a good candidate for a heat pump.

rolion wrote: »

I will realy appreciate some magic that you do with numbers and graphs and formulaes.. Can you do a "thing" comparing gas boilers VS heat pumps please !? With and without the PV panels. Thanks

pjogorman wrote: »

Eventually look to go from piped gas to electric to heat house and water.

loyatemu wrote: »

A lot of great stuff in this thread - thanks for all the work Conor.
a few things that strike me though - changing from gas to wood only makes sense if you have a free supply of wood, and from an environmental perspective I'm not convinced it's any better. I'm not sure that a heat pump will offer any great savings over gas either, unless you can run it off PV. My electricity unit rate is a little over 3 times my gas unit rate, so if your heat pump is 300% efficient or better (and other threads on here suggest 300 - 350 is realistic), you'll make some small saving, but not much and you'll have to factor in the cost of the pump and installation. Looking at my gas consumption (for heat, water and cooking) I think I could save ~130 per annum by switching to a heatpump but only if I cancelled my gas account completely. At 3K for heat pump and installation that's a 23 year payback period which isn't great. Adding solar tubes to the mix might improved that but I still don't think it would be worth doing.

Some very good questions to get the ball rolling on heat pumps, thanks! Sure. I'm currently in research mode looking into the next step, and I will do this as part of that research. For the next investment (actually reinvestment, of savings from previous investments, particularly the electric car), I'm weighing up Battery Storage or a Heat Pump. Each have their merits. Battery storage provides a way to store excess Solar PV in summer, and to store cheap night rate electricity (€0.05 / kWh) in winter to remove daytime electricity costs (~€0.16 / kWh) - like PV, prices are falling rapidly, though it is still probably on the expensive side. A heat pump would allow us to heat the house fully with electricity, meaning we can generate it ourselves at a fixed price per kWh no matter what gas / oil markets do, remove our gas connection and it's costs completely, and obviously remove our gas bills.

Loyatemu, your question got me thinking about how to calculate this for everyone's different scenario rather than just one. Your figures look about right. Just doing some maths on the spot, converting the M^3 rate for gas into €/kWh, looking up the standard gas, electricity and oil costs from the SEAI here, and using my own house's heating load for 2016, here are some (very!) back of the envelope cost comparisons:

For the year of 2016, our house required 19,898kWh of heating. The various costs for this would be:

Gas: 19,898 kWh * €0.0652 = €1,297.35
Oil: 19,898 kWh * €0.0710 = €1,412.76
Heat Pump (with 300% efficiency, with night rate electricity @ €0.05 / kWh): 19,898 kWh / 300% efficiency = 6,632.6667 kWh * €0.05 = €331.63
Heat Pump (with 300% efficiency, half with excess PV @ €0.00 / kWh and half with night rate electricity @ €0.05 / kWh): ( (19,898 / 300% efficiency = 6,632.6667 / 2 = 3,316.3334 ) * €0.00 = €0.00) + ( (19,898 / 300% efficiency = 6,632.6667 / 2 = 3,316.3334 ) 3,316.3334 * €0.05 = €165.82) = €165.82 (the assumption in here around the split between excess PV and night rate here is tricky - most excess PV will be in summer when there is little heating requirement, so this figure will fall somewhere between €165.82 and €331.63, so let's take the average €165.82 + €331.63 = €497.45 / 2 = €248.73 ).

Assuming installation costs of: Gas (€2000), Oil (€3500), Heat Pump (€4000) and Heat Pump plus PV (€7000), coupled with their yearly running costs above for 15 years gives me this chart:

Total 15 year costs including installation come to:

Gas Central Heating: €21,460.25
Oil Central Heating: €24,691.40
Heat Pump, Night Rate electricity: €8,974.45
Heat Pump with PV: €10,730.95

The installation costs are rough estimates - I haven't installed these before so I'm not sure. But you could re-do the chart above yourself based on your own installation costs and heating requirements to figure out what is cheapest for you over the 15 years.

Oil and gas prices taken from here. If the Heat Pump is 300% efficient, it takes 19,898 kWh of heat / 3 = 6,632 kWh of electricity to pump in 19,898kWh of heat energy into the house.

My Plan to Achieve Energy Freedom - The Road to Zero Energy Bills

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