Solar Electricity generation

[9fingers]

Is anyone here considering or already have, a UK domestic solar electricity micro generation scheme installed and interesting in comparing notes please?

Cheers

Bob

 

[dickm]

Now who'd have thought Bob would be considering that?????

I had my panels installed at the beginning of October, and they're generating away happily, even with our short days and low sun.

 

[miles_hot]

Bob

See this thread for plenty of information on PV etc.

Im still not 100% clear on the investment though - it still feels like a long term investment with a significant number of years until you've broken even.

Miles

 

[misterfish]

Yes. If you look at the other thread (mentioned above) that I started last year there are some basics of our system. As somewhat of a geek I have been keeping daily stats of our system including the installation of a datalogger that records data every 5 minutes.

Our first 3 months of generation finishes next weekend and we have to submit our first reading for the Fedd In Tariff payments and I'll extrapolate from that the realistic potential.

Let me know what info you're interested in. Of course, you're welcome to come and look at our system

Misterfish

 

[9fingers]

Yes. If you look at the other thread (mentioned above) that I started last year there are some basics of our system. As somewhat of a geek I have been keeping daily stats of our system including the installation of a datalogger that records data every 5 minutes.

Our first 3 months of generation finishes next weekend and we have to submit our first reading for the Fedd In Tariff payments and I'll extrapolate from that the realistic potential.

Let me know what info you're interested in. Of course, you're welcome to come and look at our system

Misterfish

Jeff, I don't know how I missed your earlier thread. I must have been spending too much time on other forums :lol:

I too will want to be monitoring my system which will be on my workshop roof. One of the companies who are quoting have been asked to look at inverters with ethernet interfaces to run the data back to the house.

I particularly what an inverter from a company that will support data collection and provide suitable software etc as well as give good tech support to a technical customer.

I'm still in the infancy of my collection of info about these systems and am sure to be back in contact when I can formulate focussed questions.

In the meantime - who did you get to do your installation and would you recommend them to others?

Cheers

Bob

 

[misterfish]

Hi Bob

We went with Southern Solar and have been impressed with their thoroughness and professionalism throughout.

We have a Fronius IG30 inverter - which allows the connection of multiple strings of PV panels. In our case we have three strings of 5 panels at different angles of inclination - one string on the main roof of the house and two on the flat roof of the sun room/granny annex.

We have a personal display (wireless) attached to our system that gives a remote display of the inverter data and also a usb attached datalogger that connects to the desktop PC. I did look at a more sophistcated version of the datalogger that would attach directly to our network switch and allow monitoring from any of our PCs, but it was silly money (over £1000).

Jeff

 

[dickm]

(already PMed this to Bob, but just for the record)
Our system uses an Aurora inverter. Basically, I took what the installers (E-motion Energy, with a base in Stirling) suggested, but reading the instructions, it has at least a USB connection and I have a disk with the software for working with it. But can't be a**sed to do the necessary connection. Probably should do something, so as to get warning of any problems, but at the moment just reading the generation meter and multiplying by 41p keeps me happy!
Hard to tell what the payback period will be, as we are now in the long dark nights of the Scottish soul, but making some optimistic guesses, it's not unreasonable.

 

[Carlow52]

As a matter of interest what life span are the different suppliers quoting for the PV panels?

Thanks

 

[9fingers]

As a matter of interest what life span are the different suppliers quoting for the PV panels?

Thanks

Most of the manufacturers seem to be standardising on quoting better than 80% of rated performance after 25 years.

Bob

 

[9fingers]

After numerous quotes and differing degrees of BS from reptiles, I have now put down a deposit for a Solar PV system for my workshop roof.
It should be installed in January as I have chosen a panel size made from unobtainium in UK but will get a better yield from my particular roof area/aspect ratio.
Predicted return is abut 11% per annum on capital invested so will better than the building society!
It certainly pays to shop around as some systems would generate more power but the extra cost reduced the yield to 9%!

Thanks for everyone's input.

Bob

 

[Dibs-h]

After numerous quotes and differing degrees of BS from reptiles, I have now put down a deposit for a Solar PV system for my workshop roof.
It should be installed in January as I have chosen a panel size made from unobtainium in UK but will get a better yield from my particular roof area/aspect ratio.
Predicted return is abut 11% per annum on capital invested so will better than the building society!
It certainly pays to shop around as some systems would generate more power but the extra cost reduced the yield to 9%!

Thanks for everyone's input.

Bob

My shed roof (well the front anyway) is the only true south facing roof we have. The main house one is E-W.

Although 2 dormers (about 8m2 each) have flat roofs, so could stick something on there. I too, am wondering about fitting solar panels to it, but up till now it was really with Thermal Solar (tubes) in mind. The cost is far less and we use a damn sight more gas for heating and DHW than 'lecy.

But this thread has got me thinking tho. Spill the beans Bob. :lol: What sort of panel, size, output, cost, etc.?

Cheers

Dibs

 

[9fingers]

Dibs,

You don't really make any significant saving on the cost of the leccy generated. The real gain is from the (crazy) feed in tariff as they call it.

The system is fitted with a meter that measures how much you generate
For very kWhr your system generates, you are paid 41.3 pence
As your current house power cant identify what you send back to the gird,
they assume that 50% is sent back and you use the rest.
BUT they cannot check this and you can use it all yourself!

For every kWhr assumed sent back you get 3p - this is the same as getting 1.5p for every kWhr you generate.

For every kWhr that you can use from what is generated, you don't have to pay for. saving maybe 13p per unit.

If you modify your domestic consumption pattern to use all the power you generate (without wasting it) you power bill should be reduced by 13p per unit.

So you definitely get 42.8p per kWhr and with care, upto 55.8p per kWhr


My system uses 10 x 235watt panels. These don't genarate the maximum all the time naturally but factoring in the location, annual variations in light levels etc, the output is estimated to be 1860kWhrs per annum.
With care, I should benefit by £1000 per annum. The crazy thing is buying that amount of power from the grid would be about £240!!

The tariff is index linked and guaranteed to be operative for 25 years

Maintenance should be no more than power washing the glass once a year.
The inverter that generates the mains power from the panels cost about £1200 and is warranted for 5years but the technology is mature.

The cost of my system will be about £8500 inc 5% vat for the hardware, installation and scaffolding to single storey roof.
The panels are 1652 x 994 x 46mm covering about 16.5 sq metres.

If you have more questions then feel free to ask.

Bob

 

[dickm]

Sounds like you got a pretty good deal there, Bob. My 3.9kW system (17 panels) cost something under £14k, including labour for fitting.

As you say, the feed in tariff is crazy, but if it's there for the taking, tax free, and if you can raise the cash, then seems mad not to go for it. It will be paying you something over 8% at worst, which you can't match that easily anywhere else.

Now, what is interesting is the Energy return on investment, that is, the amount of energy generated per unit of energy used in making the panels. An eminent friend insisted that it would take 80 years to regain the energy used, but most other people I've spoken to insist that's nonsense. The latest Dutch data I can find suggest an energy pay back ranging from under a year in Southern Spain (guess why!) up to 4 or maybe 5 years up here in gloomy Aberdeen.
Of course, the fact that the eminent friend has a vested interest in the nuclear industry may colour the figures

 

[9fingers]

You are quite correct, the total energy equation does not make sense and a panel will not generate anything like the energy that it takes to make it.

Fitting panels is not a green thing to do. fullstop. no question!

The feed in tariff is there to encourage joe public to fit generation systems that will help meet the commitment make by governments at international tree hugging conferences. If they don't achieve the agreed renewable energy levels then huge fines will be levied on them. It is calculated that paying the tariff will cost less than the fines.

For anyone considering these systems, the current tariff started in April 2010 and will be revised (possibly downwards) in 2013 or earlier if the take up exceeds the expected levels.
The bandwagon is rolling - jump on sooner rather than later.

Bob

 

[miles_hot]

Bob

Who do you go to for your pannels?

I'm always confused by the "return on investment" idea; maybe you can throw so light into the darkness of my ignorance?

If you've spent £8500 on the system and you are clearing £1000 / year that seems to mean that you will break even in 8 years, 6 months. Until that point the "investment" isn't making you any money. Am I missing something here as every one talks about this being better than money in the bank etc but until you've broken even that's not the case (assuming that the capital value of the system is zero which could be unfair).

Now, assuming that the above is right (which is a big assumption I'll grant) I modelled the effect of putting £8.5K in the bank vs on the roof and found it would take 27 years for the PV to out perform the bank:

PV:
Year Return Balance
0 0 -8500
1 1000 -7500
2 1000 -6500
...
10 1000 1500
11 1000 2500
....
26 1000 17500
27 1000 18500

Bank (2.9% interest rate - best rate from Google today)
Year Return Balance
0 0 8500
1 246.50 8476.60
2 253.65 9000.15
....
10 318.33 11312.87
11 328.07 11640.94
...
26 503.73 17873.87
27 518.34 18392.22

now all this of course assums not only a daft level of interest rates but also that energy costs will not rise inflating the rate of return etc (or would that depress the rate of return as the energy costs start to climb towards the artificial feed in rates?)...

Can someone point out to me which end of the stick I'm holding as I still can't see that PV makes sense and I really would like to be able to do it!

many thanks

Miles

 

[Dibs-h]

Bob

Who do you go to for your pannels?

I'm always confused by the "return on investment" idea; maybe you can throw so light into the darkness of my ignorance?

If you've spent £8500 on the system and you are clearing £1000 / year that seems to mean that you will break even in 8 years, 6 months. Until that point the "investment" isn't making you any money. Am I missing something here as every one talks about this being better than money in the bank etc but until you've broken even that's not the case (assuming that the capital value of the system is zero which could be unfair).

Now, assuming that the above is right (which is a big assumption I'll grant) I modelled the effect of putting £8.5K in the bank vs on the roof and found it would take 27 years for the PV to out perform the bank:

PV:
Year Return Balance
0 0 -8500
1 1000 -7500
2 1000 -6500
...
10 1000 1500
11 1000 2500
....
26 1000 17500
27 1000 18500

Bank (2.9% interest rate - best rate from Google today)
Year Return Balance
0 0 8500
1 246.50 8476.60
2 253.65 9000.15
....
10 318.33 11312.87
11 328.07 11640.94
...
26 503.73 17873.87
27 518.34 18392.22

now all this of course assums not only a daft level of interest rates but also that energy costs will not rise inflating the rate of return etc (or would that depress the rate of return as the energy costs start to climb towards the artificial feed in rates?)...

Can someone point out to me which end of the stick I'm holding as I still can't see that PV makes sense and I really would like to be able to do it!

many thanks

Miles

I'm kind of with you on this. References to a return of x%, better in the bank makes the assumption that you can "liquidate" your investment and retrieve your X thousands. Which as it has to be fitted by an "approved" installer - I would suspect a large portion of X thousands is labour. The second hand value would be significantly less than what was paid for it. Selling the house isn't really an option for most folk - as the ones who bought them yrs and yrs ago would have sold to realise the capital gains - but didn't (probably due to being happy where they were, or good schools, family nearby, etc.)

In which case it isn't a return - you've effectively lent someone your money and they'll give it back to you at a very slow rate.

I think I'm more inclined to stick with Plan A - fit Thermal Solar and knock off a sizeable amount off our gas costs. We are upgrading the plumbing ( due to it probably be older than me), etc. anyway so the additional costs are marginal, but the savings aren't.

Dibs

 

[9fingers]

Miles,

The panels are made by Sharp but there are many suppliers using semiconductors from about 6 worldwide suppliers.

Your figures have not included the promise that the feed it tariff is index linked (to one of the standard inflation measures - Possibly CPI)

Roughly 75% of the annual 'earnings' of the system comes from FIT rising with inflation, and the balance from electricity costs saved which will arguably rise at greater than inflation.

This makes modelling quite complex.

Picking a couple of figures from the air
Inflation =2.5% and electricity increase over and above inflation 3%
make the return exceed your bank investment figure in year 19.
juggling these figures can take this forward to year 15 with ease.

I don't know if your bank interest figure is gross or net of tax but any further investment income would put me in the 40% tax bracket. That is my problem but a true comparison needs to bear in mind your marginal rate of tax. Anything gained from PV is tax free.

I have not considered any increase in capital value of my house as a result of this installation but the sales pitch figures claim 5-10%.
I have decided that I will leave this house in a box (or in a state of mental decline that means I don't care) and that other medical disasters excepted, that should be in at least 20 years maybe more.

I did look at solar water heating and rejected it on the grounds of
1) much lower payback rates on capital employed (A friend has spent £4000 and is saving £200 pa and will be fortunate to live another 10 years))
2) The system would have to be on my house roof and that is shaded by next door whereas the PV system can go on my workshop roof which is not shaded.


Dibs - The labour element of the installation is £900 +5% vat
However it would be prudent to assume only scrap value for the who installation at the end of the FIT period of 25 years.

cheers

Bob

 

[RogerS]

Bob

What are the practical aspects of installation from the cabling point of view? Distance from panels to meter, capacity etc.

Roger

 

[Dibs-h]

I did look at solar water heating and rejected it on the grounds of
1) much lower payback rates on capital employed (A friend has spent £4000 and is saving £200 pa and will be fortunate to live another 10 years))
2) The system would have to be on my house roof and that is shaded by next door whereas the PV system can go on my workshop roof which is not shaded.

Bob

In our case the Solar Option can't really go on the house as it's E-W facing whereas the shed roof is S facing and slightly closer to where the "tank" will live as opposed to roof (3 stories up).

I'll have to dig out the spready again and see what the savings are likely to be. The marginal cost for us to go solar would be <£2k and the potential savings far more than £200 (probably double) so for us.

Cheers

Dibs

 

[9fingers]

Bob

What are the practical aspects of installation from the cabling point of view? Distance from panels to meter, capacity etc.

Roger

Cable runs are not an issue as the system can connect in anywhere that you have enough cable capacity. I have 2 x 4mm cables into the workshop.
System output will be about 2kw peak so even 1.5mm cable would be enough although they recommend 2.5.
The inverter connects to its own (export) meter which you own - not involved with your leccy board (import) meter at all.

My panels will be 30m or more from my import meter and main CU

HTH

Bob