Circular reasoning (Rolfe's solar energy system)

[Rolfe]

It goes like this.

1. I really should get a home charger.
2. If I get a home charger, I need a variable electricity tariff.
3. A variable electricity tariff will make my daytime usage more expensive.
4. The answer is to get a home battery and fill it with cheap electricity overnight.
5. Look at your roof, if you have a home battery it would be criminal not to install solar.
6. That will be £13,700 altogether.
7. But I could buy a hell of a lot of electricity for that. Um.
8. But I really should get a home charger.

How do you get out of this loop?

 

[salty]

It goes like this.

1. I really should get a home charger.
2. If I get a home charger, I need a variable electricity tariff.
3. A variable electricity tariff will make my daytime usage more expensive.
4. The answer is to get a home battery and fill it with cheap electricity overnight.
5. Look at your roof, if you have a home battery it would be criminal not to install solar.
6. That will be £13,700 altogether.
7. But I could buy a hell of a lot of electricity for that. Um.
8. But I really should get a home charger.

How do you get out of this loop?

Sticky with Granny. ??

 

[m4rmite]

1. Got the home charger.
2. got the variable tariff

Carried on with my life.



I would get solar and battery if i was flush - need new windows first.
Spend the rest on grandkids and enjoy life.

 

[bobbarley]

1. Got the home charger.
2. got the variable tariff

Carried on with my life.



I would get solar and battery if i was flush - need new windows first.
Spend the rest on grandkids and enjoy life.

That is our plan. Get the EV charger fitted, smart meter, and get onto OIG. Then use timers to run all our major appliances after 11:30pm. Running the washing machine and dishwasher at that time outweighs any other electronics used during the day by a significant margin.

Our boiler is approaching 30 years old, when that finally gives up we will get a heat pump fitted too and ditch gas entirely.

 

[Bam Bam]

I started with solar and battery.

Then it made sense to get an EV to use the surplus summer electricity. So I got the wall charger by the same company as the solar inverter and battery so it would all work seamlessly together.

Looking forward to getting a heat pump as well, but wife is hesitant.

It goes like this.

1. I really should get a home charger.
2. If I get a home charger, I need a variable electricity tariff.
3. A variable electricity tariff will make my daytime usage more expensive.
4. The answer is to get a home battery and fill it with cheap electricity overnight.
5. Look at your roof, if you have a home battery it would be criminal not to install solar.
6. That will be £13,700 altogether.
7. But I could buy a hell of a lot of electricity for that. Um.
8. But I really should get a home charger.

How do you get out of this loop?

About £13,400 was the cost for our solar (16 panels), battery and car charger (plus backup power facility). A lot of money but it will pay back in about 9 years depending where energy prices go. Solar panels last at least 25 years so you'll get the money back.

Would it increase the value of your house to have them?

Here's a coincidence - Garydoessolar has just released a video on how to calculate future solar savings:

 

[johnb80]

It goes like this.

1. I really should get a home charger.
2. If I get a home charger, I need a variable electricity tariff.
3. A variable electricity tariff will make my daytime usage more expensive.
4. The answer is to get a home battery and fill it with cheap electricity overnight.
5. Look at your roof, if you have a home battery it would be criminal not to install solar.
6. That will be £13,700 altogether.
7. But I could buy a hell of a lot of electricity for that. Um.
8. But I really should get a home charger.

How do you get out of this loop?

Quite a dilemma until you break the circle.

People often say like you do in (3) but in my experience it is often not the case or not wildly different. In my case, my Octopus Go Intelligent is 25.7p peak which seems competitive to most other standard tariffs. The real killer of your loop though is a combination of a tariff like Octopus Go Intelligent, your solar and your battery. Here's the result of mine:

I use very little peak rate energy, my house runs on the batteries and solar most of the time during peak time window. As you can see it's saved £70.81 this month which equates to £5.44 per day / £1988 per year. assuming similar savings your break even point should be around 7 years. Theres also the great smug factor during a power cut when you carry on as normal

I started with solar and battery.

Then it made sense to get an EV to use the surplus summer electricity. So I got the wall charger by the same company as the solar inverter and battery so it would all work seamlessly together.

Looking forward to getting a heat pump as well, but wife is hesitant.

Your wife is right to be hesitant. I do have an Air - water heatpump and several air to air heat pumps, I also have my gas condensing boiler still in the system too. The heatpumps (either type air-water of air-air) run with a COP of around 4 that means 1 kWh of electricity gives you 4 kWh heat. If your electricity tariff is say 25p kWh each kWh of heat from heatpumps is costing you 6.25p. Compare this to gas which I pay on average 4.3p kWh taking a boiler efficiency of 90% would mean each kWh of heat via the gas boiler cost 4.7p or 1.5p less than a Heatpump taking the COP of 4, when it gets cold that COP value drops, I have seen mine drop to 2.8 at times.
I set up my house with Home Assistant and programmed it to make decisions based on temperatures, gas and electricity costs. It chooses the cheapest heat source based on current conditions. Over last winter not once was the air-water heat pump chosen, the air to air was used a few times but the bulk was running gas.
I did a DIY install of the heatpump, buying it second hand but unused. I didnt get the grant because I wanted to install it myself and I wanted to retain my gas boiler. I paid under £2000 for it but even at this level I will never break even unless gas prices rise significantly.
My advice, ignore the sales guff about heatpumps, look at the amount of gas or oil you used for heating, work out how many kWh of heat that is being used to heat your property. Take that figure, divide it by 4 (the COP) and thats the amount of electricity you will need to run the heatpump. Now do a simple comparison, have a cuppa and admit your wife was right

That is our plan. Get the EV charger fitted, smart meter, and get onto OIG. Then use timers to run all our major appliances after 11:30pm. Running the washing machine and dishwasher at that time outweighs any other electronics used during the day by a significant margin.

Our boiler is approaching 30 years old, when that finally gives up we will get a heat pump fitted too and ditch gas entirely.

See my reply to BAM BAM above before you make that jump.

 

[Gomev]

EVM has studied his in depth



Plus his verdict on what to get first.

 

[Bam Bam]

Your wife is right to be hesitant. I do have an Air - water heatpump and several air to air heat pumps, I also have my gas condensing boiler still in the system too. The heatpumps (either type air-water of air-air) run with a COP of around 4 that means 1 kWh of electricity gives you 4 kWh heat. If your electricity tariff is say 25p kWh each kWh of heat from heatpumps is costing you 6.25p. Compare this to gas which I pay on average 4.3p kWh taking a boiler efficiency of 90% would mean each kWh of heat via the gas boiler cost 4.7p or 1.5p less than a Heatpump taking the COP of 4, when it gets cold that COP value drops, I have seen mine drop to 2.8 at times.
I set up my house with Home Assistant and programmed it to make decisions based on temperatures, gas and electricity costs. It chooses the cheapest heat source based on current conditions. Over last winter not once was the air-water heat pump chosen, the air to air was used a few times but the bulk was running gas.
I did a DIY install of the heatpump, buying it second hand but unused. I didnt get the grant because I wanted to install it myself and I wanted to retain my gas boiler. I paid under £2000 for it but even at this level I will never break even unless gas prices rise significantly.
My advice, ignore the sales guff about heatpumps, look at the amount of gas or oil you used for heating, work out how many kWh of heat that is being used to heat your property. Take that figure, divide it by 4 (the COP) and thats the amount of electricity you will need to run the heatpump. Now do a simple comparison, have a cuppa and admit your wife was right

Yes heat pumps aren't going to be a big cost saving because electricity is so much more expensive than gas.

However, that is because all the environmental costs get put on electricity even though it is cleaner than gas! We need to electrify everything, and the cost of the new infrastructure required is being added to the cost of electricity, reducing the incentive to electrify! Madness - it should be added to the gas bill if anything.

Anyway, I think we would need another battery in order to run a heat pump on cheap overnight electric because our E-W array doesn't provide much in the winter.

 

[bobbarley]

Do you think it’s still more expensive even if you factor in no standing charge for gas?

 

[salty]

This is all to complicated for me, it's mind blowing. ? Far to complicated than it needs to be. I'm just gonna use the Granny charger job done. ?

 

[Anon70]

There are many options you could look at but in simple terms if you can store enough electricity from solar or at your low cost time of day to use during the high cost time of day on a cheap tariff then you win.

So you could just forget the solar and invest in batteries, charge the batteries overnight (during the cheap rate) and then discharge them during the day when the cost is high.

There is also the contentious using appliances overnight option, where you run things like washing machines and dishwasher during the cheap rate time of day. Anyone who does shift work must love these EV tariffs as they are saving a fortune.

 

[johnb80]

Do you think it’s still more expensive even if you factor in no standing charge for gas?

Interesting point, I'm not sure if i programmed that in to my Home Assistant. I've just had a look, 27.5p per day is my standing charge for gas, Ive just run the info on my spreadsheet (sad I know) and my average cost per kWh for gas was 5.7p making it still cheaper than Heatpump but getting close, 0.55p per kWh of heat (that was taking the higher gas prices into account in November last year too).

If you can run on batteries then it's a complete winner without a doubt, if you want a heatpump for environmental reasons again, thats greet, if you want a heatpump to reduce heating costs that isn't going to happen.

Yes heat pumps aren't going to be a big cost saving because electricity is so much more expensive than gas.

Absolutely but, that situation can change in the blink of an eye.

However, that is because all the environmental costs get put on electricity even though it is cleaner than gas! We need to electrify everything, and the cost of the new infrastructure required is being added to the cost of electricity, reducing the incentive to electrify! Madness - it should be added to the gas bill if anything.

Totally agree with you.

Anyway, I think we would need another battery in order to run a heat pump on cheap overnight electric because our E-W array doesn't provide much in the winter.

You will need a substantial amount of storage and a hefty inverter to feed a heatpump. my 14kW air-water hp drinks the electrons at a rate of around 4kW, obviously when it reaches temps it reduces it's consumption. We often use the air tto air units top keep individual rooms toasty during winter, they work really efficiently taking less than 350w when the rooms are up to temp. My batteries keep up with these very well.

There are many options you could look at but in simple terms if you can store enough electricity from solar or at your low cost time of day to use during the high cost time of day on a cheap tariff then you win.

Yep, thats where I'm at now win, win, win!

So you could just forget the solar and invest in batteries, charge the batteries overnight (during the cheap rate) and then discharge them during the day when the cost is high.

It is very cost effective to this, if budget is an issue, battery first and then solar. Inverter sizes need to be right too, many installers fir 3.5kWh, it's not big enough but it makes their paperwork easier.

There is also the contentious using appliances overnight option, where you run things like washing machines and dishwasher during the cheap rate time of day.

Perfect, if you use Intelligent Octopus Go you can often run it to your advantage eg tomorrow morning at 06:00 my wifes car will get plugged in, this gives us off-peak until 11:00, so washing machine on, tumble drier going, Sunday roast underway all of off peak 7.5p kWh.

 

[bobbarley]

Perfect, if you use Intelligent Octopus Go you can often run it to your advantage eg tomorrow morning at 06:00 my wifes car will get plugged in, this gives us off-peak until 11:00, so washing machine on, tumble drier going, Sunday roast underway all of off peak 7.5p kWh.

So with OIG do you get the cheap rate between 11:30pm - 5:30am no matter what?

 

[johnb80]

So with OIG do you get the cheap rate between 11:30pm - 5:30am no matter what?

Yes, every night. If you then ask for a car charge you may get granted additional hours as per my Sunday morning routine. I've had a couple of days where I've had almost 16 hours on off peak rate during peak time window.

This is all to complicated for me, it's mind blowing. ? Far to complicated than it needs to be. I'm just gonna use the Granny charger job done. ?

Caveman

It's really not difficult and once setup is literally plug & play saving a fortune on energy bills.

 

[salty]

Caveman

It's really not difficult and once setup is literally plug & play saving a fortune on energy bills.

Caveman Mmmm possibly, still think people over complicate things unnecessarily, heat pump this, solar panel
that, god knows what else t'other. Not for me I'm afraid. A Granny charger will do me nicely for the mileage I'll be doing, and I'm pretty sure the leccy will be a LOT cheaper then my current £270 ish a month fuel bill that I'm currently paying. But each to there own as they say. ??

 

[Ferretusmaximus]

It goes like this.

1. I really should get a home charger.
2. If I get a home charger, I need a variable electricity tariff.
3. A variable electricity tariff will make my daytime usage more expensive.
4. The answer is to get a home battery and fill it with cheap electricity overnight.
5. Look at your roof, if you have a home battery it would be criminal not to install solar.
6. That will be £13,700 altogether.
7. But I could buy a hell of a lot of electricity for that. Um.
8. But I really should get a home charger.

How do you get out of this loop?

You might want to break it down a little.
Home charger .v. Granny charger - the home charger is for convenience (to avoid the long time for Granny charging) - the electricity costs the same.
The Solar Panels are an investment which will make you money in the long term and give you some independence from the grid. Coupled with batteries and a variable tariff they become very effective.
One approach is to get the solar panels and use the savings to fund the charger and batteries - this takes time so one question is - how long do you intend to stay in the same house?
To be thorough you could include the savings you are making from the fuel that used to go into any previous ICE car you may have had (£12 to fill the tank versus £70) to offset the capital costs of your investments (all of which will add to the value of the house).
Hope that helps.

 

[Bricktop X PWR]

All depends on your age, your circumstances, your mileage, your personal situation, etc etc etc.

It might be a sound investment for folk if

A, You can afford it.
B, You will be staying put for the next 20 years
C, You will have time to see the savings versus outlay in the first instance.

There are just sooo many variables.

I mean look at my situation for example.

Completely off grid with 5K of Solar and a 500AH Battery Bank to support.

I can plug the car in here, but only on the Sunniest of days when I have free electrons go begging.

Rest of the time its 37ppkWh.

But O.M.G! Even at that price, the savings I am making since I've given up Petrol are amazing.

With our home lives, work lives, and personal situations, EV's and how to power them???

One size does most definitely, Not Fit All.

 

[johnb80]

Caveman Mmmm possibly, still think people over complicate things unnecessarily, heat pump this, solar panel

Hehe, friendly banter

A Granny charger will do me nicely for the mileage I'll be doing, and I'm pretty sure the leccy will be a LOT cheaper then my current £270 ish a month fuel bill that I'm currently paying. But each to there own as they say. ??

Oh hell yes, you will save a fortune, it's that it would play on my mind if I was paying 4 x the amount for the electricity than I need to, worthy of consideration for that and the shear convenience if you have a driveway of simply plugging.

 

[Rolfe]

About £13,400 was the cost for our solar (16 panels), battery and car charger (plus backup power facility). A lot of money but it will pay back in about 9 years depending where energy prices go. Solar panels last at least 25 years so you'll get the money back.

Would it increase the value of your house to have them?

My quote doesn't include backup power facility, but it is for 18 panels.

If I make another 25 years I'll be pretty geriatric. I have no intention of moving, but realistically who knows. The point is really, do I spend the money on this, or hold on to it in case I want to spend it on something else. I have my annual chat with my financial advisor on Monday so we'll see what she says.

Thanks for the video links folks, I'll watch them later today.`

I should perhaps point out that this is my house. The roof faces just slightly east of south.

 

[johnb80]

My quote doesn't include backup power facility, but it is for 18 panels.

Go to option B just have battery storage, that will reduce the installation costs and increase the rate of payback.