Circular reasoning (Rolfe's solar energy system)

The payback period on the solar is estimated at five years. Of course there are a lot of assumptions in there, so who knows. My installer says he reckons maybe seven years if we include the battery cost as well. Maybe another year for the charger too? (I just missed out on a grant of £400 for that, damn!)

1715008351946.png


Looking at these numbers, I suppose back of an envelope if £7,700 will be recouped in five years then £13,700 (the total cost of the entire install) is more like nine years. I can live with that! Although I don't really expect it to work out quite so neatly.

I'm thinking, if the X-Power had been out when I got my card, I might well have been unable to resist that. But it wasn't, and I'm very happy with the SE SR. I haven't spent a huge amount more than an X-Power would have cost, overall, and I've got both the car and the solar system.
 
Rolfe said:
The payback period on the solar is estimated at five years. Of course there are a lot of assumptions in there, so who knows. My installer says he reckons maybe seven years if we include the battery cost as well. Maybe another year for the charger too? (I just missed out on a grant of £400 for that, damn!)

View attachment 26317

Looking at these numbers, I suppose back of an envelope if £7,700 will be recouped in five years then £13,700 (the total cost of the entire install) is more like nine years. I can live with that! Although I don't really expect it to work out quite so neatly.

I'm thinking, if the X-Power had been out when I got my card, I might well have been unable to resist that. But it wasn't, and I'm very happy with the SE SR. I haven't spent a huge amount more than an X-Power would have cost, overall, and I've got both the car and the solar system.
Click to expand...
If Intelligent Octopus go continues to be as generous as it is then I expect you will outperform this in the first few years at least.

Who knows what will happen to electricity import and export prices after that, but your own generation and a battery will give you flexibility whatever the situation ends up being.
 
Rolfe said:
The payback period on the solar is estimated at five years. Of course there are a lot of assumptions in there, so who knows. My installer says he reckons maybe seven years if we include the battery cost as well. Maybe another year for the charger too? (I just missed out on a grant of £400 for that, damn!)

View attachment 26317

Looking at these numbers, I suppose back of an envelope if £7,700 will be recouped in five years then £13,700 (the total cost of the entire install) is more like nine years. I can live with that! Although I don't really expect it to work out quite so neatly.

I'm thinking, if the X-Power had been out when I got my card, I might well have been unable to resist that. But it wasn't, and I'm very happy with the SE SR. I haven't spent a huge amount more than an X-Power would have cost, overall, and I've got both the car and the solar system.
Click to expand...
My installer did a very similar presentation and it wasnt too far off. I monitor my system closely (sad but true) and the stats are as follows:-

Location: East Midlands
Array Size: 6.7 kW (16 panels)
Inverters: 1 x Growatt SPH6000 1 x Victron Multiplus II 5000
Batteries: 1 x 7kWh, 1 x 14 kWh
Installation cost: £12000

Days in operation: 737
Generation from solar: 10.3 MWh

Payback
Solar generated power 13.98 kWh per day @ 27p = £3.77 per day
Battery storage 21kWh @ 19.5p Saving = £4.10 per day
Solar Export to grid 2.71 kWh @ 15p = 41p per day

Total £8.28 per day which gives a payback or break even point of 1450 days or 3.97 years. The figures will actually be better than this because I'm now exporting every night the excess stored in my batteries.
 
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My calculations are less generous but essentially I have a similar set up.

Pellet Stove = 206% return or 12 years of free heating due to RHI grant.
Solar Thermal = 71% return so far due to grant + generation.
Zappi 1 gained 90% return until replaced
Zappi 2 is only on 2% as it was installed late autumn.
6.75kW solar PV is at 48% return in 5 years with FiT but less generous numbers used
Eddi is at 140% return
Ripple is at 0% return with payments due to start in July.

No battery yet or heat pump.

EV has cost the same as ICE to own overall, just new rather than second hand.

Overall I have broken even on investments with many years of return ahead.
 
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I can take a few snaps. Right now, all I have is a stack of PV panels in my garage, and the car is roughing it outside in the rain.

I'm really not sure yet what to do about a tariff. The consensus seems to be to go with Octopus, but which one? I expect to be exporting quite a lot over the summer and I don't want to spend my every waking moment tracking prices.
 
Rolfe said:
I can take a few snaps. Right now, all I have is a stack of PV panels in my garage, and the car is roughing it outside in the rain.

I'm really not sure yet what to do about a tariff. The consensus seems to be to go with Octopus, but which one? I expect to be exporting quite a lot over the summer and I don't want to spend my every waking moment tracking prices.
Click to expand...
Octopus GO Intelligent would be my choice. 7.5p 23:30 to 05:30, 26.9p peak and 15p export. It does give you additional hours under their control too.

If youre not with Octopus, please use my code to get you and I £50 paid into our accounts.

I run my system so that all that I generate is fed into the grid at 15p, the house runs on battery all day / evening and the batteries recharge overnight at 7.5p. No messing about just run it. That said I have tweaked my system to export surplus battery to Octopus during the evening which earns a little bit, but you don't have to do that.

J
 
I've got a queue of people, including my supplier, offering me an Octopus code. I'm thinking of holding a raffle!

I think you're describing the tariff my supplier is talking about.
 
Rolfe said:
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?
Click to expand...

Do you need a fast charger or cheap electricity?
I.e. do you need the charging speed and convenience of a fast charger?
If the answer is yes, get the charger first.
Once you have that installed, and used it for a month, then look into the next priority: cheap electricity? Switch to an EV tariff for a month.
During that period, try and see if you can shift your usage to the times when electricity is cheaper. If you can do it with an EV tariff, you will certainly be able to do it with solar.
By the end of this you will have data to show you if battery storage plus solar is going to give you the necessary return on investment.
Plus you will have had an opportunity to think about it a bit more.

If on the other hand the only reason to do all the above is because you are driven by ‘green intentions’ then save up money or get a loan and do all the above in one go.
 
fnegroni said:
Do you need a fast charger or cheap electricity?
I.e. do you need the charging speed and convenience of a fast charger?
If the answer is yes, get the charger first.
Once you have that installed, and used it for a month, then look into the next priority: cheap electricity? Switch to an EV tariff for a month.
During that period, try and see if you can shift your usage to the times when electricity is cheaper. If you can do it with an EV tariff, you will certainly be able to do it with solar.
By the end of this you will have data to show you if battery storage plus solar is going to give you the necessary return on investment.
Plus you will have had an opportunity to think about it a bit more.

If on the other hand the only reason to do all the above is because you are driven by ‘green intentions’ then save up money or get a loan and do all the above in one go.
Click to expand...
I think Rolfe is a bit further along with this project ?, many decisions already made.
 
Bam Bam said:
I expect other EV drivers will go through the same thought process though once they see their roof as a potential source of power/money!
Click to expand...
Probably so, I researched the whole situation for about 18 months before ordering the installation and then another 6 months designing and building an add on powerwall. There's a lot of misinformation out there by well meaning people that really doesn't help (I'm not referring to anything said on here BTW :) )
 
Rolfe said:
I've got a queue of people, including my supplier, offering me an Octopus code. I'm thinking of holding a raffle!

I think you're describing the tariff my supplier is talking about.
Click to expand...
No problem, I donate my £50's to charities :)

Many other forums have a forum code and they pick up the referrals to donate to worthy causes etc. Saves some bickering which can and does occur with a free for all.
I'm glad youve got started, it sounds like your sparky has his finger on the pulse with regards to tariffs. Octopus is a great company, there are of course others, just avoid at all costs British Gas is my advice.
 
Rolfe said:
I've got a queue of people, including my supplier, offering me an Octopus code. I'm thinking of holding a raffle!

I think you're describing the tariff my supplier is talking about.
Click to expand...
I have a code too lol
 
I'll just use the one from my installer - seems only polite!

Not a lot to show for it so far, the roofing guys have gone off to another job, see you tomorrow.

1715696929452.png


And the electrician has just left too.

1715696999087.png


Nevertheless he says he reckons the solar system will be up and running tomorrow, though it might be Thursday before the car charger is done.
 

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