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

Conor20

I've long been interested in energy efficiency and renewable energy projects. I now finally have a canvas to try these out on - We bought a house about a year ago, and it's a typical early-boom-time late 80's/early 90's build. It's paper thin. There was no insulation in the house at all. The windows were single glazed. The front door.. Well let's just say, the rain came in, in large puddles, under the door during the winter storms the first year we were in there. Coupled with this, I've been hunting for ways to cut down on expenditure and find ways of generating decent returns for the (far away) retirement fund without a huge amount to save each month. The electricity and heating bills for the first year we spent in the house were really expensive, as was the cost of running the car, and I had this terrible vision of us running on the treadmill forever, just working to keep ahead of these expenses.

Around the same time, I was really impressed with some projects posted on Boards - particularly the DIY Rainwater Harvester built by a poster on the Plumbing and Heating board, as well as the posts from several people who have installed solar panels - both hot water and electricity generation. I've also learned a lot about financial efficiency, and calculating Return on Investments from the American blogger, Mr Money Mustache (though I'm more interested in energy than money). I decided to be more proactive in shedding these electricity, heating and transport expenses, so we could spend that money on other things that bring at least some benefit to us, or to use it to start saving for retirement. I decided to do some small steps - buying an energy monitor for the house and starting with switching all of the lights in the house from incandescent to LEDs. This was a bit of a revelation for me. It cost €55 to buy the LEDs online. They are rated to last about 15 years, and they saved €87 in the first year. That means they paid for themselves in less than a year, and they're going to save €87 * 14 = €1,218 over their 15 year lifetime. If I put that money in the bank, it'd be worth perhaps about €150 in 15 years. In the stock market, it might be worth between €0 and €500. It's certainly unlikely to be worth €1,200. And so I came to the realisation that with technology that has come along in the last few years, it seems conceivable that it may be possible to completely remove the €4000 or so of energy bills between electricity, heating and petrol we're paying each year. If I retire in 35 years, that's €4000 * 35 = €140,000 that we could spend on other things (or not have to earn, and pay tax on, in the first place).

And so I started planning, and costing energy initiatives to calculate their payback, and whether they save more money than they cost in the long run. If they do, and the return is better than what I might expect to get from a bank or the stock market, then it makes more sense to do it than do anything else. I was surprised by the quick paybacks, and how much sense it makes to do a lot of these things - installing LEDs, putting in insulation, installing double glazed windows, installing a wood burning stove with a back boiler to heat the house, switching to an electric car. This is my plan:

Put in an energy monitor so we can see what's consuming and costing us what, and how much we're saving with these updates.
Change all light bulbs to LEDs
Put in radiator heat reflectors to stop sending half of our heating out of the house
Insulate the attic
Install a wood burning stove with back boiler to reduce gas heating costs
Replace the petrol car with an Electric Car
Retrofit Dual flush, low water toilet cisterns
Install Double Glazed Windows
Install a Rain water recycling system to fill the toilet cisterns with rain water
Install Solar PV Panels to reduce electricity bills
Add a battery system for Solar PV Panels to completely remove energy bills forever
Put in an Air Source heat pump and remove the gas boiler forever
Install an inverter to allow the house to be powered by the electric car
If necessary, add Solar panels for hot water
Selling energy to the grid. The final frontier - actually making money from energy and beyond. (Hopefully this becomes possible in Ireland at some point in the future)
End Game: Retire on energy income, invested energy cost savings and super-low living costs.

The last one might be a stretch, but I like having it to aim for. I decided to keep a blog on the way there because it worked out well when I wanted to do an Ironman a few years ago. I'll keep a blog of my progress, and how each thing works out - in terms of cost, energy savings and financial savings. So here goes. Although it may take a few years, I'm determined to follow the plan above. I'll keep this thread updated with my progress.

Conor.

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kennypowers

unkel wrote: »

In a typical setup you can use the batteries when the grid is down, but you can't charge them up with solar PV, so once they're empty, that's it

That said, with a typical say 5kWh battery, this is enough to power some basics like phone chargers, wifi router, bulbs and tv for several days

novice question but why wouldnt your solar pv be able to recharge some of your battery? I live in an area that gets numerous power outages a year and as a result have become interested in getting pv as a supplement when this occurs.

wexfordman2

kennypowers wrote: »

novice question but why wouldnt your solar pv be able to recharge some of your battery? I live in an area that gets numerous power outages a year and as a result have become interested in getting pv as a supplement when this occurs.

Technically, it is absolutely possible, but regulations do not permit it. In the event of a power cut from the mains, all solar production must be automatically disconnected, and the pv system disconnected from the mains.

It is not even permitted to discharge the remaining capacity of your battery into the mains of the house,.if you wish to use up your battery capacity during a power outage, it must be via a dedicated and completely isolated circuit from the mains.

All to do with fire regulations and safety of esb personal working in power lines outside of your house.

unkel

If you do have regular grid blackouts that have a bad impact on your household, you could consider an off grid system.

SlowBlowin

You don't need to do it all at once.

In my layout the workshop is on the side of the house, so initially I put the batteries in the workshop and powered the lights and the fridge freezer which were in the workshop. I also had my internet/wireless stuff in there so when we had a power cut we had Internet and a working fridge, as well as USB chargers etc. That was a good phase 1, then as I added PV capacity I added a feed into the house, totally independent of the existing wiring system.

[Deleted User]

SlowBlowin,

What would you recommend for getting some solar EV charging going?
Or where to find more info.
I have a zappi charge point .

Cheers

SlowBlowin

BrownFinger wrote: »

SlowBlowin,

What would you recommend for getting some solar EV charging going?
Or where to find more info.
I have a zappi charge point .

Cheers

Hi

Not having an EV (other than the bike) I am probably not the best person to ask. Have you seen the episode of fully charged where they use a Zappi on solar ? That would be a good starting point.

Unkel has a solar install and an EV, I bet hes done some research.

From the technical perspective, there is talk that trickle charging (granny cable) can shorten the lifespan of some battery packs, so a system with stationary battery that charges, then dumps into the car at a higher rate is preferred. The trouble is that cars charge at tremendous rates, and most home PV systems are only capable of charging at limited rates. As I said I have no knowledge of this and Unkel is probably better placed to comment, but do watch that episode of Fully charged if you can, they have the MD of Zappi on.

KCross

SlowBlowin wrote: »

From the technical perspective, there is talk that trickle charging (granny cable) can shorten the lifespan of some battery packs,...

I've never heard that and I doubt its true.

Its high rates shorten the life span, not low rates.

SlowBlowin

KCross wrote: »

I've never heard that and I doubt its true.

Its high rates shorten the life span, not low rates.

Yes you are most likely correct, it was something I "heard" that using granny 100% can lead to some issues.

In my experience, as you said, its always the other way round. It might a miss quote and they were referring to the poor efficiency of the granny cable vs a faster charger..

KCross

SlowBlowin wrote: »

...they were referring to the poor efficiency of the granny cable vs a faster charger..

That is true.

The car chargers are usually optimised for 16A or 32A charging so charging it at 10A tends to be less efficient. Maybe instead of it being 90-95% efficient it is now closer to 80% efficient.

unkel

BrownFinger wrote: »

What would you recommend for getting some solar EV charging going?
Or where to find more info.
I have a zappi charge point .

That's good. The only thing you need then is to install a PV system. The Zappi charger can send all electricity that you produce more than you are consuming, to the car. Provided of course the car is plugged in.

I would recommend you go for the biggest system you can afford and will fit on your roof. At the very least 3kwp. The bigger the system, the cheaper per watt installed it is. And once it's on the roof, you won't really have to worry about it ever again.

Conor20

(I had to split this post into several posts as I was having trouble linking from external images, and had to use attachments which have a limit of 5)

I started this project five years ago with a simple question: how can I provide for my children's future, whilst ensuring they have a future? That means finding a solution for life that's reconciled with climate change, but in a way that creates wealth and positive returns. Technologies have done us all favors in this regard and I found myself investing in a few simple measures early on that allowed us to save for bigger changes, which saved more money. We saved as much of those savings each month as we could so we had a pot of money that was growing increasingly quickly with money we otherwise would have just spend on light, heat and transport. They were things like replacing our petrol car with a second hand electric car, cycling rather than owning a second car, installing double/triple glazed windows, installing LEDs throughout the house, and adding attic insulation.

Six months ago, we took these accumulated energy savings and invested in achieving a low energy cost household. We wrapped the house in insulation, we switched the heating from gas heating to an electric heat pump, and we installed a 5.8 kW Solar PV array. Additionally, we replaced the gas cooker hobs with electric induction hobs (Ikea sell them starting at €39) to fully remove gas bills from our house forever. We had already switched to an electric car from our old petrol car. Our house now requires a lot less heat, that heat comes from an electric heat pump, and for a lot of the year, that electricity comes from Solar panels on the roof.

All of this is in a bog-standard 1980s three bed semi-d originally built with minimal thought to running costs. If we can do it, anyone can. Five years ago, our energy costs across our car, heating, hot water and electricity totaled €4,703.56 per year. Now they total €778.13 a year.

Had we changed nothing and continued with our 2015 baseline, over the next 10 years we would have spent €47,035 on the energy required for our lives. Instead, with the changes we've made, we'll spend €7,781, freeing up €39,254 and giving us a lot more financial stability. One of the key lessons we've taken from the unpredictable nature of the last two years is that finding ways to earn more money is really hard, and when you do, you pay a lot of those increased earnings in tax. We've realized it's a hell of a lot easier to spend less money that it is to earn more, and the net effect on our cashflow is the same.

SolarPV
We had already installed a 2.5kW SolarPV system on the front of our house three years ago, but as we now are heating our house with electricity, and powering our car with electricity, I saw it as a financially positive investment to increase the size of our SolarPV system to 5.9kW by adding extra panels on our flat back roof.

Our day rate is €0.1874 and our night rate is €0.927. Our SolarPV system generated 1850kWh of electricity in the first 4 months of operation, but this was spring and early summer. Based on previous data from the smaller SolarPV system we had, year round, it will generate 4,260 kWh per year. The battery soaks up almost all export, but I think we'll export about 250 kWh per year, mostly during stretches of long blue-sky days in May/June. That leaves 4,260-250 = 4,010 kWh per year that we'll consume, offsetting the need to pay for it. Taking a simple day rate calculation for the value of this electricity is €0.1874 * 4010 = €751.474 per year. The figure is more complicated for two main reasons:
(1) Detracting from this net impact cost, some of the electricity consumption the SolarPV offsets, we would otherwise have consumed at night rate (€0.927). I estimate this to be about 50%. So (4010 * .5 * €0.1874) + (4010 * .5 * €0.0927) = €561.60. The SolarPV system cost €5,198 after the €1,950 grant so the yearly ROI is €561.60 / €5,198 = 10.8% . It's warrantied for 20 years, so the full payback of investing in solar will be in the region of 561.60 * 20 = €11,232. Higher if energy prices go up, which they are very likely to do.

(2) If your original baseline is a petrol or diesel car, and you switch to solar, putting the solar generated electricity into an electric car would save more as it is saving money you otherwise would have been spending on petrol. A litre of Petrol contains 12.8889 kWh, burned in an internal combustion engine with a max. efficiency 38%, so your €1.26 litre of petrol gets you about 4.8kWh, or €0.2625 / kWh. So if you're doing calculations on making a big switch to cut costs in your life by switching to SolarPV + an Electric Car, and you put 2,000kWh of solar into your car, that will give you an extra bonus saving of 2,000 * €0.2625 = €525.00 ( 2,000 * €0.1874 = €525- €374.8 = €150.2

Here's a day in May - solar generated 23.7kWh of electricity. We consumed 21.9kWh of that between powering the house, heating water in the hot water tank via the Heat Pump, and the excess went into the battery. The electricity stored in the battery continued to power energy consumption of the house after the sun went down. So of the total of 21.9kWh we used that day, we imported only 2.7kWh from the grid. Our electricity bill in May was €15.18 - it's quite remarkable to me that on sunnier months like this, we can power our house, transport and heat almost entirely from solar.

If you're working out a solar installation for your house, the SEAI grant will pay you €3,000 for a 4kWp system with a battery, €2,400 for a 4kWp system with no battery, and €1,800 for 2kWp system of about 8 panels. This would fit within the 12m^2 size which requires no planning permission even if it's on the front of your house. Also, the Irish government are mandated by the EU to introduce a feed in tariff scheme by the June 2021, so people with SolarPV installations will be paid for excess electricity back to the grid.

Battery
The battery saves money in two ways: in summer, it stores excess solar which would otherwise have been exported. Looking through the summer figures, the resultant stored solar we used about two third of the time during the day rate (€0.18 kWh) and about a third during the nighttime (€0.09 / kWh). We stored an average of about 5 kWh per day over those 6 months - maxing out the 8.2kWh of storage almost every day during May, June and July, and averaging about 3kWh a day in April, August and September. That translated to a saving of 6 * 30 * .66 * 5 * €0.18 = €106.92 +
6 * 30 * .33 * 5 * €0.09 = €26.73 . So €106.92 + €26.73 = €133.65 per year in the summer months for the battery.

Secondly, in winter, we can charge it at the night rate (€0.09) and use it to power the house to avoid the day rate (€0.18), saving €0.09 per kWh. We do this for the 6 less sunny months of the year, offsetting 8.2kWh of daytime consumption every day, so saving 6 winter months * 30 days per month * 8.2kWh * €0.09 / kWh saving = €132.84 per year.

The battery thus saves €133.65 + €132.84 = €266.49 per year. The battery's net cost was €1900 which gives a 1900 / 266.49 = 7.1297 year payback of the battery, or a 14% yearly return (266.49 / 1900) if the full cost of the battery is written off at the end of the 7 years.

So, right now the battery is not a positive investment. It may be in the future when homes are rewarded for providing flexibility to the grid. It does also provide one other thing however - continued power in the event of a grid blackout. The SolarPV and battery inverter system comes with a power back-up connection which provides a power outlet which will continue to work if the grid goes down. The SolarPV system continues to work with the battery, but not the rest of the house or the grid which is a legal requirement. This means that if the grid goes down, we can continue to power key appliances and the car indefinitely with solar in the event of a prolonged grid blackout.

Insulation
Insulation is not the most exciting of things to do but it is by far the most important of anything listed here. Before installing SolarPV or a Heat Pump, your house should be really well insulated. A few years ago, we replaced all of our windows with double glazed windows, installed a new airtight front door to stop drafts and insulated the attic. This time we finished the job. We wrapped (e.g. installed external insulation) on the side and back of the house, and installed internal insulation on the rooms at the front of the house (as modifying the front of the house would have required planning permission). The insulation cost €9,300 with the €4,500 SEAI grant, but it has utterly transformed the house from a drafty cowboy build three bed semi into a warm and cozy house that stays at a constant temperature which will require drastically less energy to heat it for the next 50-60 years of its lifespan. It used to be like a leaky bucket into which we had to constantly pump heat (e.g. money) into to keep heated. Now it's cozy and warm through winter without requiring much heat input to keep it that way.

Heat Pump
A heat pump is quite a miraculous machine. Other heating systems, such as gas boilers, wood stoves and oil fired boilers are 50-80% efficient. That is to say 50-80% of the energy you put into them in the form of fuel comes out as useful heat. Heat Pumps can be 200-400% efficient by virtue of that fact that they are not creating heat, they are simply pumping it in from the outside. For every one watt of electricity you power the Heat Pump with, it delivers 2-4 watts of heat into your house. The result is a heating system which is incredibly energy efficient. Couple it with a SolarPV system on your roof and when the sun is shining, you have ultra-efficient, completely free heating and hot water.

Heat Pumps work the same way that a fridge does, but in reverse. A fridge has a loop of piping that runs inside and outside of the fridge. It uses a valve to compress a fluid inside the pipe inside your fridge. As the liquid becomes more dense, it sucks in heat from the air cooling down the air in the fridge. A pump keeps the fluid moving around the loop. Another valve outside the fridge expands the liquid, and as it expands, it can hold less heat, so it dumps the heat it absorbed inside the fridge outside the back. This keeps the fridge cool inside. A heat pump heating system is exactly the same but in reverse. It uses two valves and an electric pump to pump a liquid around in a loop.

The Heat Pump we installed is a Hitachi R32 Yutaki-SCombi 2 5HP 200L. The Coefficient of Performance (unit of heat energy out / unit of electrical energy to power it) varies with a few factors, such as the outside temperature and the temperature you are heating water to. For 35C water, the CoP varies from 2.7 (outside temp of -7C) to 8.35 (outside temperature of 12C). For 55C water, it goes from 1.85 (-7C outside temperature) to 6.35 (outside temp of 12C). It's listed with an all up CoP of 4.4 here. This is the full CoP table and other specs of the system:

So that means for every 1 watt of electricity our heat pump consumes, it's pumping 4.4 watts of hot water into the hot water tank, or out into the radiators.

[Continued in next post]

Conor20

[Continued from above]

The Heat Pump consists of a fan unit which sits outside, a fridge-sized inside unit that sits inside (replacing the gas boiler), and a 200l hot water tank. The water tank will replace an immersion hot water tank, as it does the same thing with 25% of the electricity. We mounted the fan unit up on the side of the house so it was out of the way:

Since installing the heat pump in March of this year, we have never run out of hot water - that includes showers, baths for the kids, washing and general usage all day while we were home during the lockdown, so I would say we have well and truly tested the capacity of the system and it's come up trumps.

We installed underfloor heating on the ground floor and this results in a more efficient use of the heat pump. It allows us to run the heat pump to store heat in the floor of the house during the night or when there is excess solar generation. The floor stores a lot of heat and releases it slowly, so it will effectively heat the house for days. Underfloor heating is surprisingly simple - basically, put down insulation, put down a big loop of pipes and pour two inches of concrete on top:

Underfloor heating isn't essential however. Two households we know have recently switched over to Heat Pumps from gas and oil heating respectively, without underfloor heating. They did change their radiators to Heat Pump radiators which are more effective at distributing heat. We installed these upstairs replacing the old rads:

One other attribute of a heat pump, though we'll probably never have need for it, is that if it gets too hot in summer, a heat pump can run in reverse and act as air conditioning to cool down the house. I asked the installer about this and it does require the addition of a "condensation kit" to deal with condensing water if you put it into cooling mode, which costs about €500 to add. Still, might be useful if summers get a lot warmer in the coming years.

Emissions
Driving our petrol car used to release 2,600 kgCO2 per year. Switching to an electric car reduced that by 1,630 kg CO2 per year to 970.9 kg CO2. But looking back at my maths on that - before we installed SolarPV, we were charging it year round with electricity from the grid. A few things have changed that for the better since:

The electricity grid in Ireland, like most countries around the world, has continued to go green, adding a lot of renewable energy capacity in the last 5 years and retiring several coal and turf power plants. It's now mostly renewables and gas.
In summer, we are no longer charging our car from the grid, which has an average emissions intensity of 389 gCO2 / kWh, we are charging it from our SolarPV, which have an emissions intensity of about 18 gCO2 / kWh (this is the emissions released during their manufacture and transport divided by all of the kWh they will generate in their lifetimes). Because we installed an 8.2kWh battery, even if the car isn't plugged in during the day, we can that much solar into it via the battery in the evenings, which amounts to about 50km in an older Leaf.
As renewables installed in Ireland is mostly wind, and it's windier in the winter in Ireland, that means the grid releases much lower CO2 per kWh in winter than it does in summer on average. Renewables average 37% in the winter months, with an average CO2 intensity of about 270g/kWh.

So this means that we now charge our car for six months with an average of 270gCO2/kWh and the other six months with an average emissions of 18 gCO2 / kWh. We drive about 300km per week, which consumes 48kWh of electricity. So the net emissions are 48 * .270 * 4 * 6 = 311.04kgCO2 (6 months of winter) + 48 * .018 * 4 * 6 = 20.736kg CO2 (six months of summer) . So our driving is down to 311.04 + 20.736 = 331.776kg, a whopping 2,268.224kgCO2 reduction on our old petrol car. It also shows that as time goes on, and grid is increasingly powered by renewables, electric cars will get cleaner and cleaner.

The installation of our heat pump has also removed all gas that we used to burn. We used to spend €793 a year on gas at €0.09 / kWh. So we used roughly €793 / €0.09 = 8,811.11 kWh of gas yearly. Gas emits .23kg CO2 per kWh from a gas boiler with reasonable efficiency, so our gas usage was emitting 8,811.11 * .23 = 2,026.55 kg CO2 every year.

We used to need 8,811.11 kWh of gas to heat the house, which implies we consumed about 7,048.88kWh of heat yearly in the house given a boiler efficiency of about 80%. However, we now have the house fully wrapped in insulation and the BER inspection rated the heat consumption of the house at 57.5 kWh/m/year. The house is roughly 80M^2, which gives a yearly heat consumption of 57.5 kWh/m^2 * 80m^2 = 4,600kWh. So the insulation reduced the heat consumption of the house by about 2,500kWh per year (7,048.88 - 4,600 = 2,448.88 kWh reduction).

Our Heat Pump, with a coefficient of performance of 4.4 delivers that 4,600 kWh of heat required by the newly insulated house with 4600 / 4.4 = 1045.4545 kWh of electricity. I'll use the same grid and solar CO2 intensity above, and I'm guessing we use about 66% of the heat & hot water in the winter months when it's powered by the grid, and 33% of it in the summer months when it's powered by solar. So that gives 1045.4545 * .66 * .27 = 186.3 kgCO2 (winter months) + 1045.4545 * .33 * .018 = 6.21 kgCO2 (Summer months) = 192.51 kg CO2 in total for our heating and hot water year round.

So heating our house with gas emitted 2,026.55 kg CO2 every year, and the Heat Pump + Insulation + SolarPV combo heat the house emitting 192.51 kg CO2 per year, giving a reduction of 1,834.04 kg CO2 per year. So a pretty significant saving of 1,827.83 * 20 = 36,556.6 kg CO2 over the next 20 years.

The Financial Impact all up
Calculating everything requires having a baseline to compare against. I looked back to see what we were spending on energy before we started this whole process. That looked like this:

It was costing us €3250.56 a year to run our petrol car (including maintenance and tax, both of which decreased considerably with the switch to the electric car). It was costing us €793 per year to heat the house with the gas boiler. Both of those bills have now disappeared. Our electricity bill was originally €660. So our combined energy and transport costs were €4,703.56 per year. Everything runs on electricity now - our power, transport, heating and hot water, and we generate most of that electricity ourselves with the Solar panels for part of the year. All of these bills combined look like they will come in at €778.13 this year. So these combined measures of Insulation, switching to an electric car, switching to a heat pump and installing SolarPV will reduce our costs by €3,925.43 a year.

The totals for the work came to €24,898 after the grants. We availed of a pretty significant €10,550 of grants from the SEAI (see here). Looking at the numbers so far, a conservative estimate is that the changes will pay for themselves in 9-10 years. The SolarPV system is warrantied for 20 years. The Heat Pump is warrantied for 10. The insulation is warrantied for 20 years with a life expectancy of 30. I'll do a more comprehensive analysis of the payback when I have a full year of data (and more time!) but I think this is a solid investment. Particularly given the increase in quality of life you experience with a fully insulated house, and the daily buzz of seeing solar panels on your roof print money for you.

The BER of our house has gone from D1 consuming 236.42 kWh / sqm / year to A3, consuming 57.5 kWh/m/year.

I would just reiterate that when we moved into the house 6-7 years ago, the wind literally blew through it. Single glazed windows, no insulation at all, a front door which used to let the wind and rain in.

I think why I value these changes so highly is that it's really difficult to earn more money. And when you do, you pay tax on those earnings. It's much easier to reduce your costs. So seeing our energy costs fall by €3,925.43 every year into the future removes a lot of stress about money, and makes it much more realistic for us to consider one or both of us retiring early if we want to.

A note on the upfront costs of this work - we were lucky to have been able to save up the cost of these works by pretty relentlessly setting aside all of the savings from our previous changes. Not everyone will be able to get this money together and so I hope this is reflected in how the government support lower income households. It strikes me that retrofitting insulation, heat pumps and SolarPV as a much more helpful way to help people than a winter heating allowance for fuels which leave the household broke again next winter. Getting rid of the bills entirely would free up households from this repetitive treadmill, as well as keeping more money in the country that currently flows out to countries who export fossil fuels.

I'm also aware that not everyone has enough time or interest to run complex numbers, so I will make some broad summaries that I think will be true for most people:

Insulate your house. I know it's boring but just to it. It will sit there saving you money for the next 30+ years and will make the house much more pleasant and cozy. There's an SEAI grant of €4,500 for wrapping your house.
Switching to an electric car, particularly a second hand EV, will save you a lot of money in the long term in fuel, maintenance and tax costs
For a family household, SolarPV is a good investment, better than just paying down your mortgage. If you consume little electricity, and there remains no feed-in-tariff, it may not be. But for most people it now is a financially positive investment. You can get an SEAI grant of €3,000 for installing SolarPV, and there will almost definitely be a feed in tarif by June 2021, as the EU begin fining Ireland for not having one by then. If you don't have an electric car or Heat Pump, install about 2kW. If you do have a Heat Pump and EV, it's worth installing up to 6kW of capacity if you have space.
If you switch to a heat pump to heat your house, that will both save you money, and allow you to make further savings from a SolarPV system
If you switch to an electric car, and install SolarPV, that will allow you to make further savings from SolarPV

So there you have it. If you want to permanently lower your energy costs into the future, I recommend insulating your house, switching to an electric car, installing SolarPV, and heating your house with a Heat Pump.

Gerard93

Thanks Conor20 for such a detailed post fantastic what you have achieved... now I have to read it all again !!

SlowBlowin

I just think this post is beautiful in its construction and detail, I have not fully digested the content but I have no doubt that's fantastic too. I need to read it a few times, but what a project, love it, good job !

tails_naf

That's a brilliant result Conor20, really shows what can be done, and that going green is viable. Regarding the heat pump, is it fair to say with the cost of a unit of oil being around 6 or. 7 c per kwh, you need a CoP of at least 3 to break even with a heat pump using day rate units, or do you only let it run at night? I have oil at the moment, about 1600l a year, which is around 750 euro at the moment, so hard to see switching to air to water as being cost effective for me.

unkel

Gas is well under 5c/kWh (including VAT and carbon tax), so a lot of heat pumps will be more expensive to use if you use 24h electricity rates. Would be stupid to still be on a 24h rate if you have a heat pump (or an electric car for that matter)

Also the cost to switch is very material, heat pumps are expensive, even after subsidies. And from anecdotal evidence they don't seem to be very reliable compared to good old oil / gas boilers and when they break they seem harder to fix with fewer people around to fix them. But that can of course be attributed to the fact that we are adapting newer technology and we are in a change phase. Few car mechanics will be able to fix a high voltage battery problem with a Nissan Leaf either

Heat pumps will also only work in very well insulated housed

Of course you will lose your gas / oil bill and any standing charges or delivery costs. And stop using fossil fuels. The grid is getting cleaner every year, so using electricity for heating (particularly at night) is a major step in the right direction

NIMAN

This is a very interested thread but there is an awful lot of data and info in it for someone who has just discovered it.

@op, do you have an overall figure for
(1) how much you have spent in changing your house/lifestyle etc to be more energy efficient, minus grants
(2) savings youhave made so far by doing so

I appreciate its a long term project and will pay back over the rest of your life, but curious as to how much it would cost the average person to being making these types of changes?

beertons

That's class. Have to sit down with a coffee layer and read it in entirety.

KCross

Conor20 wrote: »

SolarPV
We had already installed a 2.5kW SolarPV system on the front of our house three years ago, but as we now are heating our house with electricity, and powering our car with electricity, I saw it as a financially positive investment to increase the size of our SolarPV system to 5.9kW by adding extra panels on our flat back roof.

(2) If your original baseline is a petrol or diesel car, and you switch to solar, putting the solar generated electricity into an electric car would save more as it is saving money you otherwise would have been spending on petrol.

Fair play on all the works you have done.

EV/Solar integration
Looking at your pictures it looks like you have a standard Rolec charge point and you said a Leaf. How do you manage the flow of electricity from the Solar to the car in that case as it will be pulling a constant 3.6kW for hours and not reacting to when clouds roll in or other appliances fire up thus causing you to unnecessarily pull expensive day rate electricity.

It would typically require a Solar integrated smart charge point to manage that automatically. Are you doing it manually? I know your battery helps too but that still wouldnt cover it.

Are you manually checking a monitor to see if there is 3.6kW of excess Solar and then plugging the car in/out accordingly?

Heat pump
How noisy is that outside unit? I hear alot of complaints about noise from those units when they are running at full tilt. Being tied directly to your outside wall is also not typically recommended as it can cause vibration through the walls. Usually they are on an independent foundation on the ground but I can see why you would mount it high to get it out of your way. Any complaints from the neighbours on the noise? Any noise inside your own house from it?

Muahahaha

Excellent post Conor. Agree with you 100% on the heat pump, I replaced 25 year old storage heaters with an air to air HP last year and between that, new windows and some internal insulation on a north facing wall I saw an immediate drop in electricity bills. From memory October-Nov 2018 was 253 euro and then the same period in 2019 was 156 euro. Regarding the air conditioning function it is rarely needed in Ireland but when it is by god it is nice to have it. Arrived back to the house a few days last summer and it was sweltering inside at 27c with no breeze so it was great to be able to run the air con for 20 minutes and get the temperature down to 18. The unit I have is a Mitsubishi and it also has functions as an air purifier and a dehumidifier, it has an app as well to monitor kwh usage or turn it on over wifi when you are out of the house.

Just on the external insulation, you said it is done on the gable side and back side of your 3 bed semi. How were the SEAI with this in terms of the grant, I had thought they only pay out if all sides of the house are completed? Also did any energy assessor say that it would be less efficient if not fully wrapped or talk about cold bridges? And can you recall the cost of the EWI per sqm? I had got quotes for it before and from memory it came to about 150sqm so not a small cost. In my own situation Id would like to do the gable side of the house which is often cold but as far as I know the SEAI wont give the grant for only one side so Id have to pay the entire cost myself.

FionnK86

What an achievement Conor. I wish I'd money to buy my own place. Landlord not accepting proposals to improve the house as we're footing the energy bills.

slave1

Nice post and thanks for the carbon reductions.

Perhaps a small point but in Winter when you are charging the battery at night, that electricity is mostly renewable generation versus not charging up the battery and using non-renewable at say midday lunch. So it's not just a financial saving, it's a carbon saving too.
Charging your battery at night in Winter will probably result in about 10% electric loss and another 10% loss when discharging during the day, again small point.
Perhaps it's buried in your assumptions.

Well done again

Evd-Burner

I've been following this a long time and have I have implemented a few the items you have with a plan to implement more

Next item on my list when I can get the moment together is external insulation the back and gable wall. I have already had the front cavity pumped and front internal plasterboard pumped which made a huge difference. I'm just not sure how the grant works with just doing the gable and back.

Conor20

tails_naf wrote: »

That's a brilliant result Conor20, really shows what can be done, and that going green is viable. Regarding the heat pump, is it fair to say with the cost of a unit of oil being around 6 or. 7 c per kwh, you need a CoP of at least 3 to break even with a heat pump using day rate units, or do you only let it run at night? I have oil at the moment, about 1600l a year, which is around 750 euro at the moment, so hard to see switching to air to water as being cost effective for me.

unkel wrote: »

Gas is well under 5c/kWh (including VAT and carbon tax), so a lot of heat pumps will be more expensive to use if you use 24h electricity rates. Would be stupid to still be on a 24h rate if you have a heat pump (or an electric car for that matter)

Thanks! I spent a day thinking about this to try find the right measurement to directly compare gas and a heat pump from a cost perspective. Because the efficiencies are so different, the input costs don't really make sense to compare. When heating your house, the thing that actually matters is the cost of delivered heat, so I think the right measure for us to compare is € / kWh of delivered heat. If you can get gas for €0.05/kWh with a gas boiler with an efficiency of 80%, then your cost of delivered heat is €0.05 * (1/0.8) = €0.06 / kWh of delivered heat. If Oil costs about €0.07/kWh, then it will similarly cost about €0.08 / kWh of delivered heat.

We next need to work out our average cost of electricity for the Heat Pump. So a quick delve into the cost of electricity from the SolarPV array. It generates 4,260 kWh per year, warrantied for 20 years, 4,260 kWh * 20 = 85,200kWh over it's warrantied lifetime, €5,198 / 85,200kWh = €0.06 / kWh. I would say we're powering the Heat Pump with a mix of SolarPV, Night Rate electricity and day time electricity roughly equally, so the average electricity cost for the Heat Pump is - ( (€0.06 * .33) + (€0.08 * .33) +(€0.19 * .33) ) = €0.11 / kWh on average.

For a heat pump with an efficiency of 440% (e.g. a CoP of 4.4 meaning for every 1kWh of electricity it consumed, it pumps 4.4kWh of heat into your house), at an electricity cost of €0.11 / kWh means €0.11 * (1/4.4) = €0.03 / kWh of delivered heat.

So a heat pump is roughly half the cost to run, at €0.03 / kWh of delivered heat, to gas at €0.06/kWh of delivered heat or to oil at €0.08 / kWh of delivered heat.

unkel wrote: »

from anecdotal evidence they don't seem to be very reliable compared to good old oil / gas boilers and when they break they seem harder to fix with fewer people around to fix them. But that can of course be attributed to the fact that we are adapting newer technology and we are in a change phase. Few car mechanics will be able to fix a high voltage battery problem with a Nissan Leaf either

Heat pumps will also only work in very well insulated housed

This was certainly true a few years ago but there are huge new estates surrounding us and every house in them are fitted with heat pumps, so I think Heat Pumps are common enough now that most plumbers have already or will soon skill up on installing and maintaining them. Heat Pumps have been in widespread use since the 80's/90's in Scandinavia so I wouldn't be too worried about parts not being available. Yep - you need a well insulated house for sure. People should see Insulation + a Heat Pump as being the one job. The SEAI grants do soften the blow a lot though, with €4,500 for insulation (€6,000 for a detached house) and €3,500 for installing a Heat Pump.

unkel

Modern condensing oil and gas boilers are much higher efficiency than 80% though. And I have my doubts if a heatpump can really deliver a COP of 4.4

But yeah, tune that down a bit, tune up the efficiency of the boilers in your calculation and take night into account (try to minimise running the heat pump during the day) and your conclusion still stands

The calculation of the help from solar is flawed though. Most solar PV is not directly used (but sent to the grid, stored in an electrical battery or hot water storage) and when you need it most for your heatpump, none is available

Conor20

NIMAN wrote: »

@op, do you have an overall figure for
(1) how much you have spent in changing your house/lifestyle etc to be more energy efficient, minus grants
(2) savings you have made so far by doing so

This reply turned into a post in it's own right. Anyway, here we go! I've made some approximations here but this is the rough sequence by which we've tried to get off of the treadmill of energy costs! -->

Bought an energy monitor so we can see what's consuming and costing us what in 2013
- Cost: €50
- Savings: €1,000. The €1,000 is a complete guess but it made us way more energy aware as we were before and we pretty much immediately started being more efficient. It became fun to be efficient as we could see what we were saving whereas before, it felt like depriving ourselves for no reason
Switch to a Day / Night rate electricity meter and tariff in 2014
- This is free to do and I recommend doing it. I think you just need to ring your electricity supplier and ask to switch to a day/night rate. You can then run appliances, charge your electric car, etc. at night at a much cheaper rate. We were able to save about €200 a year with the night rate meter before we switched to the electric car, and as soon as we switched to the electric car, it was saving us about €400 a year.
- Cost: free
- Savings: About €1,500 since 2014
Changed all light bulbs to LEDs in 2014:
- Cost: €100
- Savings: 495.165 kWh per year | €87.29 per year | 274.8697 Kg CO2 per year. So in 6 years, it's saved us 87.29 * 6 = €523.74 so far for the €100 invested, so €523.74 - €100 = €423.74 in profit
Bought an electric bike in 2015 and used it as a way to avoid having a second car until 2020:
- Cost: €750
- Savings: A car costs about €5,000 per year between depreciation, tax, insurance, maintenance and fuel, so it's saved about €25,000 - €750 = €24,250.00 in the last five years. Cycling is insanely good for saving money and once you get used to it, it's a lot of fun too. This is probably the best thing you can do if you want to reduce your costs, just get rid of a car in favour of cycling. Yes, it will be hard at the start and yes, you will get rained on. However, it's not so bad when you know you saved €5,000 / 250 (workdays a year) = €20.00 tax free for cycling that day.
Insulated our attic in 2015:
- Cost: €598
- Savings: €204.40 per year | 2,555kWh | 587.65kg CO2 per year. So this has saved us about €204.40 * 5 = €1,022.00 so far, so we're €1,022 - €598 = €424.00 in profit. Attic insulation will sit there forever and so will comfortably live there for 25 years, giving €4,512 of savings on the initial €598.
Switched to an electric car in 2014:
- Cost: €16,000 (this was back in 2014 - second hand Nissan Leafs are way cheaper now, you can replace a second petrol/diesel car if you have one, with an older Leaf now for €8,000)
- Savings: €2,954.8 per year | 11,224 kWh per year| 1630 kgCO2 per year. €2,954.8 * 6 = €17,728.8 of savings so far. So €1,728.8 of "profit" against our old petrol car. Wahoo - this is the first time I've realised our Leaf has "Broken even" versus our old Nissan Almera. This is a bit of a hallow celebration as cars, even electric, are very expensive to own.. Better to cycle. But if you must drive, definitely switch over to an electric car.
We installed a wood burning stove with a back boiler in 2016 - though at this point, I recommend just going straight to a heat pump and leap frogging a wood burning stove. It was fun and we learned a lot but people on this thread rightly pointed out that it's not good for local air quality - it also turns out even efficient sealed stoves leave particulate matter inside the house - so it was fun while it lasted but I'm glad we've switched over to a Heat Pump now for all of our heating. Unless you have free wood, an electric heat pump will be cheaper to run.
- Cost: €4000
- Savings: About €3000
- Verdict: Don't install a wood stove now, just go straight to a Heat Pump to hear your house
Installed Double Glazed Windows and sealed front door in 2016:
- Cost: €7,000
- Savings: €303.21 per year | 3,790.08 kWh per year | 706 kgCO2 per year. So they've saved €303.21 * 4 = €1,212.84 so far, so we're "down" €7,000 - €1,212.84 = €5,787.16 on the windows. Though insulating your house and particularly installing new windows brings a lot of comfort and security benefits. They'll pay for themselves in 23 years.
- Fun Fact, here's the old and new doors beside each other at the time we installed them:
Installed 2.2kW SolarPV Array in 2017
- Cost: €4313 (This would cost €2513.00 today as the SEAI grant now gives €1,800 of a grant for a system of this size now)
- Savings: €351.25 per year | 2088 kWh per year | 1,123kg of CO2 per year. So this has saved us €351.25 * 3 = €1,053.75 so far and will save €351.25 * 20 = €7,025.00 over it's warrantied lifetime
Insulated the House (External Insulation on the back and side wall, internal insulation on the front), Installed a Heat Pump in 2020:
- Cost:
  - Heat Pump cost €8,500 (€12,000 - €3,500 SEAI grant)
  - Insulation (External + Internal): €9,300 (€13,800 - €4,500 SEAI grant)
- Savings: See post above! Because this is such a big change, and is tied in with everything we've done above in terms of installing double glazed windows, switching to an EV, etc. the best way I can see to calculate savings is to look at what we used to spend on energy all up, which was €4,703.56 per year, and now we're down to €778.13 a year. This includes the changes above, but adds up to a total energy cost reduction of €3,925.43 a year.
Increased the SolarPV installation from 2.2kW to 5.9kW in 2020
- Cost: €5,198.00 (€7,148.00 - €1,950 SEAI grant)
- Savings: 4,260 kWh per year | €561.60 per year | 1,491 kgCO2 per year, so this will pay for itself in 9.2557 years and is warrantied for 20 years, so make us 561.6 * 20 = €11,232 in total on our €5,198 investment (preventing 1,491kgCO2 * 20 = 29,820 kgCO2 in the process)
- Comment: As we had switched to an electric car, switched to heating our house an electric heat pump - everything in our house was now powered by electricity so it made sense to try to generate as much of this electricity ourselves by installing additional Solar panels on all of the remaining roof space we have. So these panels now will just sit there eating into our electricity bills for the next 20 years

So adding all of these up: we've spent a total of €50 + €100 + €750 + €598 + €16,000 + €4000 + €7,000 + €4313 + €8,500 + €9,300 + €5,198.00 = €55,809 over the last 7 years, and it's saved us a rough estimate of €1,000 + €1,500 + €523.74 + €24,250 + €1,022 + €17,728.8 + €3000 + €1,212.84 + €351.25 + €561.60 = €51,150.23 of savings so far. Most of these investments will continue generating savings into the future - the SolarPV system is warrantied for another 19 years and will save about €10,000 over that time, the electric car is still running so will continuing "saving" versus our old petrol costs, my electric bike is still going strong with a few hours maintenance a year, the insulation is warrantied for another 24 years.. I'm guessing the €55,809 will save about €100,000 over the next 20 years. The point is that once we’ve made these investments, we reap the benefits in terms of money, increased comfort and financial security for a long time to come. It's also worth noting that we didn't magically have €55,000 on day one - we started with small things and just saved relentlessly for the next thing, which allowed us to save more money each month and so on. It made it a lot of fun.

kippy

New windows, external doors and insulation are probably the biggest bang for buck in older houses from what I am seeing, with oil at its current cost. Upgrading the oil burner, depending on age makes a big difference too.
We moved into a 2002 detached house a few years ago and haven't felt the need to invest in any of these improvements yet.
Pretty much every other change is pretty expensive and comes with some big enough potential downsides.
All of this of course in a world where oil remains reasonably inexpensive.
The charging infrastructure for electric cars is still woefully inadequate but is improving. Once this happens, will probably go down this route.

ercork

Conor20 wrote: »

Thanks! I spent a day thinking about this to try find the right measurement to directly compare gas and a heat pump from a cost perspective. Because the efficiencies are so different, the input costs don't really make sense to compare. When heating your house, the thing that actually matters is the cost of delivered heat, so I think the right measure for us to compare is € / kWh of delivered heat. If you can get gas for €0.05/kWh with a gas boiler with an efficiency of 80%, then your cost of delivered heat is €0.05 * (1/0.8) = €0.06 / kWh of delivered heat. If Oil costs about €0.07/kWh, then it will similarly cost about €0.08 / kWh of delivered heat.

We next need to work out our average cost of electricity for the Heat Pump. So a quick delve into the cost of electricity from the SolarPV array. It generates 4,260 kWh per year, warrantied for 20 years, 4,260 kWh * 20 = 85,200kWh over it's warrantied lifetime, €5,198 / 85,200kWh = €0.06 / kWh. I would say we're powering the Heat Pump with a mix of SolarPV, Night Rate electricity and day time electricity roughly equally, so the average electricity cost for the Heat Pump is - ( (€0.06 * .33) + (€0.08 * .33) +(€0.19 * .33) ) = €0.11 / kWh on average.

For a heat pump with an efficiency of 440% (e.g. a CoP of 4.4 meaning for every 1kWh of electricity it consumed, it pumps 4.4kWh of heat into your house), at an electricity cost of €0.11 / kWh means €0.11 * (1/4.4) = €0.03 / kWh of delivered heat.

So a heat pump is roughly half the cost to run, at €0.03 / kWh of delivered heat, to gas at €0.06/kWh of delivered heat or to oil at €0.08 / kWh of delivered heat.

Good post Conor. The SEAI have also worked out these delivered energy costs for the different efficiencies/COPs. See p2 of this doc:

https://www.seai.ie/publications/Domestic-Fuel-Cost-Comparison.pdf

antoinolachtnai

ercork wrote: »

Good post Conor. The SEAI have also worked out these delivered energy costs for the different efficiencies/COPs. See p2 of this doc:

https://www.seai.ie/publications/Domestic-Fuel-Cost-Comparison.pdf

The heat pumps section there is incorrect as far as I can tell and is best disregarded. There is no differential pricing like this for incremental consumption of electricity.

ercork

antoinolachtnai wrote: »

The heat pumps section there is incorrect as far as I can tell and is best disregarded. There is no differential pricing like this for incremental consumption of electricity.

I think most resedential customers would be in band DD - the others can be ignored.