Circular reasoning (Rolfe's solar energy system)

[Rolfe]

Just had a real stroke of luck. The corner of the garage where the installer wants to put the battery and other toys was occupied partially by a couple of really old bicycles I was never going to ride again. Neighbours who have recently moved in across the road have a big skip in their driveway full off all sorts of junk. I plucked up the courage to ask, and the husband helpfully lifted the bikes into the skip for me. Saved me the chore of getting them into the MG4 without scratching anything and driving them 15 miles to the council tip. Result.

 

[Bam Bam]

Well, it's all go. My installer has upgraded the inverter to 5kw at no extra charge. I have signed on the dotted line and paid a 10% deposit. Work is scheduled to start in two weeks.

Result!

Are they going to de-tune the 5kw until they get the G99 permission?

Glad you won't have to wait months like we did.

Our solar was great today - made nearly £4 export even after filling the car to 100% (from 80% so 10kwh)!

 

[Rolfe]

I sent off the "Letter of Authority" to get this done this afternoon. (For some reason the original email requesting this didn't get to me.) He's very hopeful it will be fine.

It has only just started to warm up here today, a bit of sun, got my bed linen washed and dried, hopefully these fatuous sunbeams will be toiling to greater effect by the end of the month.

 

[GaryMG4]

I sent off the "Letter of Authority" to get this done this afternoon. (For some reason the original email requesting this didn't get to me.) He's very hopeful it will be fine.

It has only just started to warm up here today, a bit of sun, got my bed linen washed and dried, hopefully these fatuous sunbeams will be toiling to greater effect by the end of the month.

Here in sunny Norfolk I've added 31 kWh this month (2 charges) at a total estimated grid cost of £1, those sunbeams are doing there job here.

 

[Rolfe]

I look forward to doing the same!

 

[DBedford]

Just calculate the payback period, for us solar and batteries, plus the orientation of our rook is a no go. Now if we were 20 years younger it would be very different story. The EV changer alone will take a few years to payback, but we bought it for convenience.

 

[Rolfe]

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!)

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.

 

[Bam Bam]

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.

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.

 

[johnb80]

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.

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.

 

[Rolfe]

Wow.

 

[EVsince2016]

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.

 

[Rolfe]

I can't see me doing all these sums. I'd prefer to get it more or less automated and to know that I'm doing all right, rather than get bogged down in the minutiae.

 

[Rolfe]

Today's the day. The materials are coming this afternoon and work starts tomorrow.

 

[johnb80]

Today's the day. The materials are coming this afternoon and work starts tomorrow.

Yay, good luck, I'm sure all will be good.

Thread on the installation and photos etc?

 

[Rolfe]

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.

 

[johnb80]

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.

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

 

[Rolfe]

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.

 

[fnegroni]

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?

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.

 

[Rolfe]

You're a bit late to the party, the electrician is crawling around my fuse-box cupboard as I type.

 

[johnb80]

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.

I think Rolfe is a bit further along with this project , many decisions already made.