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I'm still toying with the idea of getting a solar solution for my new property. It has gas central heating (system boiler with hot water storage tank) and a gas hob cooker. I have an EV that I currently charge via the super cheap Octopus Go nightly rate.

There's no point charging the EV off solar during the day and missing out on the ~5p per kWh SEG export payment to offset when it would cost me 5p to charge in the off-peak Go tariff. Daytime electricity usage doesn't seem like it will be that high.

I thought I could use solar PV to heat hot water but then there's no point missing out on the 5p per kWh export to save on the 3p per kWh of gas. So, from a purely financial point of view, it makes no sense to use solar to charge my EV during the day nor use it to offset gas usage. As much as I tried, it just doesn't financially work out. Even if it was slightly at a loss then i could at least somewhat justify it by the environmental benefits.

Anyway, and then it occurred to me what about solar thermal? My parents in law have a system that they have had for a long long time (before the huge craze of solar PV). The roof space required for that is much less so I was just wondering if that would make things more financially better?

How good are more modern solar thermal systems? Are they relatively cheap? I know generate any expert revenue like solar PV but wondering whether it would allow me to completely avoid gas usage during the warm parts of the year and thus enough to have a reasonable payback period. Thoughts?
 

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I put a solar thermal system in a previous home of mine. The cost: I bought cheap new/unused vacuum tube panels and done the plumbing myself. It heated the water true. To stop it overheating the circulation pump needed to run. After the water was hot, it was doing nothing. Solar PV uses more roofspace but is cheaper, and the excess power can be used/sold. I have PV now, and use excess power for washing machine, tumble dryer, dishwasher etc. Being all solid state, it's a lot more reliable too.
 

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Discussion Starter #3
So sounds like doing a brand new solar thermal installation is worse off financially than solar PV.
 

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What about augmenting with a heat pump? the gas has to go some day, and 1kwh of PV power can be used to generate 3-4kwh of heat energy, so becomes cheaper than gas and is more cost effective than the 5p/kwh for export. Top off with a small battery, and you can use Octopus Agile instead, for even cheaper overnight/off peak (the only expensive period is 4-7pm which your battery can cover) so even if your EV needs charing for longer/outside the Go window, and your heat pump needs to run the other 21 hours a day in winter, you're better off. I think.

PS, final tip, get a thermal battery too for storing some heat to cover yourself during the 4-7pm window if you need heating/showers then.
 

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Just seen that solar thermal is included in the new Government Green Support Package (Solar PV is not) so this may help justify the cost although with PV you can power a heat pump or heat battery and use that to heat your water. I believe Solar Thermal needs an annual service.
 

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There's no point charging the EV off solar during the day and missing out on the ~5p per kWh SEG export payment to offset when it would cost me 5p to charge in the off-peak Go tariff. Daytime electricity usage doesn't seem like it will be that high.

I thought I could use solar PV to heat hot water but then there's no point missing out on the 5p per kWh export to save on the 3p per kWh of gas. So, from a purely financial point of view, it makes no sense to use solar to charge my EV during the day nor use it to offset gas usage. As much as I tried, it just doesn't financially work out. Even if it was slightly at a loss then i could at least somewhat justify it by the environmental benefits.
I'm not sure I understand your argument. You seem to be saying it's not worth having solar PV because it's not worthwhile to charge your EV or heat your water. But you don't install PV to do those things (though they may be a useful side effect) - you do it to save on your day rate electricity cost. Is that not worthwhile for you?
 

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I'm not sure I understand your argument. You seem to be saying it's not worth having solar PV because it's not worthwhile to charge your EV or heat your water. But you don't install PV to do those things (though they may be a useful side effect) - you do it to save on your day rate electricity cost. Is that not worthwhile for you?
I'm not making an argument. Just trying to seek a better understanding. Let me explain further: In terms of my own personal situation, I was keen to get solar PV but after crunching the numbers, it doesn't work out financially for me. If it was just a little off then I would take it on the chin as it would be lowering my own personal carbon footprint but it's not close. Therefore right now I can't justify it.

I was still wanting to lower my carbon footprint (with my financial means though), I then thought about solar thermal and wondered if that might be any more financially viable. I haven't heard much about it in recent years so I wasn't even sure if the technology has improved. My only exposure to it is a very old system installed by my parent's in law.

I had a look at the cost of both ground source heat pump and an air source one. Neither are within my immediate budget so they are also out of the picture.
 

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Let me explain further: In terms of my own personal situation, I was keen to get solar PV but after crunching the numbers, it doesn't work out financially for me. If it was just a little off then I would take it on the chin as it would be lowering my own personal carbon footprint but it's not close. Therefore right now I can't justify it.
For most customers a typical payback would be in the 10 -15 year range - less if you have a good roof arrangement (much less if you don't need scaffolding) and if you're at home a lot during the day. I'd be happy to take a look at your roof and give you a free estimate.
 

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For most customers a typical payback would be in the 10 -15 year range - less if you have a good roof arrangement (much less if you don't need scaffolding) and if you're at home a lot during the day. I'd be happy to take a look at your roof and give you a free estimate.
Thank you that is extremely kind of you. I might take you up on the offer but it will have to be further down the line as I'm currently having renovation work at the house which will be changing the roof structure.

I fully appreciate that getting it all done at the same time will be cheaper but I've already stretched budgets for the house and the renovation work. I don't think I'll be able to afford a solar solution for at least a year from now. I'll definitely reach out nearer the time though if the offer of a free estimate is still available. Thanks again :-D
 

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Ok, understood. Perhaps just bear in mind that scaffolding can represent about 20% of the cost of a solar install (£800-£1000).
 
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Ok, understood. Perhaps just bear in mind that scaffolding can represent about 20% of the cost of a solar install (£800-£1000).
Yes I understand, it's been a difficult pill to swallow but it's unfortunately a cost I have to take on the chin. I've tried to make peace with it in the hope that the situation will be better in a years time than now. Whether that be in terms of cost of the solar install, more efficient panels, better SEG tariffs or some combination of all of this.
 

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With the advent of TOU leccy tariffs and historically low gas prices it has become extremely difficult to put forward a financial case for Solar. In effect you have to have the resources to be green and b the cost.

As the cost of batteries reduces there will come a point where they make sense when combined with TOU tariffs.

What most people should be doing is to spend their money on reducing demand, the biggest ones being blocking off chimneys and rigourously reducing draughts, but for some reason these subjects do not get discussed. The average household could 1/2 their energy demand without any noticeable change. About 1/2 of most peoples leccy bill is made up of their things left on 24/7 amounting to 200-300w continuous. 200w X 24 hr x 365 days = 1752 kwh per yr !! = c £280/yr

People just waste energy and then work on how to create more.
 

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Discussion Starter #13
With the advent of TOU leccy tariffs and historically low gas prices it has become extremely difficult to put forward a financial case for Solar. In effect you have to have the resources to be green and b the cost.

As the cost of batteries reduces there will come a point where they make sense when combined with TOU tariffs.

What most people should be doing is to spend their money on reducing demand, the biggest ones being blocking off chimneys and rigourously reducing draughts, but for some reason these subjects do not get discussed. The average household could 1/2 their energy demand without any noticeable change. About 1/2 of most peoples leccy bill is made up of their things left on 24/7 amounting to 200-300w continuous. 200w X 24 hr x 365 days = 1752 kwh per yr !! = c £280/yr

People just waste energy and then work on how to create more.
My house has around that 300w continuous usage. I had a look at what was causing it and the main offenders were fridge/freezer and my internet router with WiFi. Nothing I can do about the fridge/freezer but I tried turning off the Internet router when I wasn't usually at home or during night but I often found it a huge pain during those times when I needed the Internet outside of main hours. Also, turning of the Internet router doesn't work so well when you've got home automation devices. But at least I've gone through that evaluation and assessment and I know that I've reduced the power draw down to the minimum I am happy to get away with. But I understand your point that some people do not go through that process.
 

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I should hope your fridge and freezer are not on that much otherwise its duff. My freezer of old was on 24/7 before i realised it had degassed ! and my new one A+++ hardly comes on.

Most of the 200-300w is things on standby eg tele,telephone, battery chargers including the car one. printer,routers,lights in cookers,clocks, etc all adds up.
 

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I should hope your fridge and freezer are not on that much otherwise its duff. My freezer of old was on 24/7 before i realised it had degassed ! and my new one A+++ hardly comes on.

Most of the 200-300w is things on standby eg tele,telephone, battery chargers including the car one. printer,routers,lights in cookers,clocks, etc all adds up.
Fridge and freezer contributed but the main draw was the internet router and the home automation devices. There is a power penalty for all these internet of thing devices, which are not really designed to be turned off. A modern day house is not the same place as it was before the internet.
 

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Fridge and freezer contributed but the main draw was the internet router and the home automation devices. There is a power penalty for all these internet of thing devices, which are not really designed to be turned off. A modern day house is not the same place as it was before the internet.
Maybe there’s a case for a small solar PV system and battery just to take care of these base loads that you can’t eliminate?
 

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and that's one of the reasons why octopus is great. they give you that granular data.

My previous provider, E.ON, who installed the smart meter, said I have to wait a year before they would give me any data.
Our background useage is about 80watts. I need to sort out our Outdoor 30W PIR light that keeps coming on throughout the night (and now daytime too!)
 

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Discussion Starter #18
Maybe there’s a case for a small solar PV system and battery just to take care of these base loads that you can’t eliminate?
Interesting. As mentioned by KenB, I have calculated and the cost of my base load power in the house is costing in the region of £300 a year. That is a fair chunk of cost that would help towards the cost justification of a solar PV solution.

The overall conclusion of this thread though seems like a solar thermal solution isn't going to be more financially viable than a solar PV solution. So I think I'll stick to the idea of a solar PV solution.
 

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Interesting. As mentioned by KenB, I have calculated and the cost of my base load power in the house is costing in the region of £300 a year. That is a fair chunk of cost that would help towards the cost justification of a solar PV solution.

The overall conclusion of this thread though seems like a solar thermal solution isn't going to be more financially viable than a solar PV solution. So I think I'll stick to the idea of a solar PV solution.
How have you worked that out?
If your base load is 0.25 kWh, that's 6kWh/day.
I'm assuming an Agile tariff of around 7p average that works out at ~£150/year
 

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Yes but very few people are on Agile and smart meters are in the minority.
I
I hope you are not implying that if it costs 1/2 the amount its OK to waste energy. Waste is waste and western man needs to buck up.
 
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