Thinking about solar.....

[Deleted User]

Hi all.. rep has just left, and the situation seems better than I thought. Nothing signed! Full quote being emailed.

The figures are for a 4kW system, "tier 1 panels". Mounted clear of roof tiles using stainless steel brackets, so no wind pressure on tiles.

House roof angle 35 degrees; orientation 20 degrees off south.

Estd power generation p.a. 3704 kW.

Generation + feed in approx £250 PA index linked.

As we are early retired, usually in house all day most days, and have son with mobility problems who rarely goes out, his estimate was that we would use 50-80% of self-generated power. Current monthly electricity £53 payment per month, so estimated reduction of electricity bill up to £555 pa if all generated power used; (obviously less saving if lower percentage of generated power used).

Panels 20 year guarantee, inverter 10 year guarantee - inverter extra guarantee to 20 years for £200.

Total installation costs £4995 + vat. Vat stated to be at 5% meantime, but HMG lost vat case in Europe so vat will have to go up to 20% at some point in future, but no date set. 5% vat = total cost £5244, 20% vat = total cost £5994.

Seems like an interesting deal to me, based on that info. Any pitfalls that we might have missed?

WR

Martyn1981

Wild_Rover wrote: »

Seems like an interesting deal to me, based on that info. Any pitfalls that we might have missed?

Hiya WR, a few thoughts.

Price doesn't look too bad, obviously the cheaper the better now, but I don't know how much competition there is in your parts.

Generation sounds slightly high, perhaps 3,300 but I'm guessing location. Have a play with PVGIS so you can stick a pin 'on your house', see PV FAQs for a walkthrough.

Leccy savings, won't be that high, I'll wish you luck, but your consumption/spending isn't massive, so with the best will in the world I can't see you saving that much, and if you have a standing charge, then that won't be saved at all.

Hopefully you can make use of 50%, but that still takes effort. If your system is generating 3kW+ and there's no washing to do, nothing to switch on, then you may only be using 500W and exporting the rest.

After checking PVGIS, what would 50% of that be multiplied by the unit price of your leccy?

Not sure what return you are looking for, but if you can save £200 + £230 (FiT and export), is that an ok return for you on £5,244?

Mart.

[Deleted User]

Martyn1981 wrote: »

Hiya WR, a few thoughts.

Price doesn't look too bad, obviously the cheaper the better now, but I don't know how much competition there is in your parts.

Generation sounds slightly high, perhaps 3,300 but I'm guessing location. Have a play with PVGIS so you can stick a pin 'on your house', see PV FAQs for a walkthrough.

Leccy savings, won't be that high, I'll wish you luck, but your consumption/spending isn't massive, so with the best will in the world I can't see you saving that much, and if you have a standing charge, then that won't be saved at all.

Hopefully you can make use of 50%, but that still takes effort. If your system is generating 3kW+ and there's no washing to do, nothing to switch on, then you may only be using 500W and exporting the rest.

After checking PVGIS, what would 50% of that be multiplied by the unit price of your leccy?

Not sure what return you are looking for, but if you can save £200 + £230 (FiT and export), is that an ok return for you on £5,244?

Mart.

Hiya Mart - thanks for that. I'll revisit any of these points when quote comes in, but a couple of things come to mind.

- the generation figure was based on roof angle, orientation, postcode and zero overshadowing and seemed a remarkably precise figure. (Could just have been salesmanship, of course, but said to have been calculated via recognised industry software (we were told!))

- usage - presently £53 per month, but likely to rise as we have recently installed a conservatory, which I am sitting in at the moment, with elec heater on! 2 grown up children seemingly permanently hooked up the internet, one son unlikely to leave home due to medical history. Therefore, long term, three adults in all day, most of the time. Our washing machine, tumble dryer, dishwasher etc are mostly used during the day; with solar installed, likely behaviour shift would mean that it would be unlikely we would use these in evenings or overnight.

- a "return" of £430 would be over 8% on 5224.

I'll post more info on receipt of details.

Thanks for your help.

WR

tunnel

I'm pretty certain that the FiT is the same for a system size 4-10kWp as it is for the upto 4kWp.
With a roof your size maybe(funds allowing) go bigger, this should then bring down the cost per kWp and also ensure that even on cloudy days(during winter) your baseload should be covered.....just a thought

Exiled_Tyke

I'm firmly with Martyn on this one. All the figures look too optimistic. Using the website I gave you earlier, I stuck a pin in somewhere in the middle of Scotland (between Aviemore, Fortwilliam and Perth. This came back with an estimate of 3290 Kwh per year (16 per day in June, down to 2 per day in Dec). (2 Kwh won't provide much a saving in winter to anybody's bills)

Don't underestimate the challenge of trying to both use the energy produced and save on your bills. Juggling the washing machine (heats at the beginning of it's cycle), the dishwasher (beginning and end) against the changing weather is neigh impossible. You'll just finish the ironing when the sun unexpectedly comes out. And don't forget to turn everything else off when you put the kettle on otherwise your paying for that too. (And do take into account that most individual heating appliance (irons, kettles etc) us more energy than you'll be producing for a lot of the year).

The electric heater challenge has been discussed quite a bit on these forums. You need something with lots of control as the winter sun generates at below 1Kw at lot of the time which is less than the lowest settings on many heaters. And of course once the sun goes in and you really need the heat more - your'e paying for it again.

Seriously getting to 50% usage is not to be taken for granted and 80% seems totally unrealistic to me.

Also I hope you are not confusing the return with a bank account return (which is often done). The difference being with the bank account you have your initial lump some still, here you do not. 8% per year mean that even with these optimistic figures the system will take 12 1/2 years to pay for itself. Sorry but with the costs as quoted and a more realistic set of estimates this doesn't look like it will be financially viable.

One final quick question to test the honesty of your rep: did they mention that panel performance deteriorates slightly year on year?

Exiled_Tyke

A few further thoughts. If you on the cost near Aberdeen then better figures look likely - even then mostly around the 3600kwh mark.

If you are looking nearer to 3300 then:

FIT works out closer to £220 per year.
Electricity savings at 50% would be roughly: 1650 units at say 10p (for simplicity) = £165 per year.

Total savings = 385.

This now gives a payback period of 13 1/2 years. This would be a pretty poor investment.

[Deleted User]

(Hi Exiled Tyke.. I saw your posts, but before dealing with them I need to make the following correction...)

Oh carp.

I've made an error in the info I gave yesterday - apologies! I was thinking last night that my electricity usage was lower than I remember, so checked my bank statement this morning.....

£53 pcm is my monthly GAS bill ; my monthly ELECTRICITY bill is £73. I had transposed the figures in my notebook (they come out of my account as two deductions on the same day... my eyes obviously jumped a line!). My persent annual electricity charge is therefore £876, not £636.

(Again, that annual figure will only go up as we now have an electrically heated conservatory. That was not there when our yearly estimate was done.)

The paperwork I have from gas/elec company gives the Tariff Comparison Rate of 12.56p per kWh.

The solar panel quote includes the following calculation. (I've had to reformat it)

FINANCIAL BENEFITS FROM YOUR SYSTEM

ANNUAL ELECTRICITY GENERATED - 3704kWh

ANNUAL FIT GENERATION INCOME £162.61 (kWh x 0.0439) #1

ANNUAL FIT EXPORT INCOME £89.82 (50% of kWh x 4.85p) #2

ANNUAL BILL SAVINGS £277.80 (50% of kWh x 15p) #3

TOTAL ANNUAL BENEFIT £530.23 (total of #1 + #2 + #3)

Notes

#1 – this is your main payment through the government Feed In Tariff (FIT) also known as your ‘generation payment’. You will be paid for 100% of your generated electricity at the rated of 4.39p/kW (for systems up to 4.0 kWp). Payments will rise with inflation and you still get paid for all of your kW no matter how much of the solar electricity you use on site.

#2 – this is the additional FIT payment known as the ‘export payment’. Basically the government are buying your electricity back from you as your system is linked to the national grid. It is assumed that solar panel systems will export half of the generated power back to the grid for other UK households to use. This is why it is calculated at 50% of your total generation at a rate of 4.85p/kW. You will still
receive this payment even if you use more than 50% of your generated electricity as usage from your solar panels is not metered.

#3 – this is how much you will stand to save on your annual electricity bill if you use 50% of your solar electricity; this tends to be what he average solar panelled household uses. The more you use though the more you will save too. The 15p comes from today’s average price of electricity set by energy companies – the more their prices increase in the future the more you stand to save and safeguard your bills as a solar system owner.

#4 – this is your total financial benefit per year taking into account the 3 previous calculations.

I'm a bit puzzled by the differences in the generation estimates - why is there a discrepancy, if the software is accurate and to an approved standard?

(We live on the outskirts of Edinburgh, btw. At the time of switching supplier last year, in the pre-conservatory days, the annual usage estimate was 8,369.95 kWh.)

Any more thoughts?

Thanks in advance for any comments.

WR

Edit - I used the website with pin on our house and a -20 as we are 20 degrees off true south. The figure was a total of 3650.

Exiled_Tyke

Very interesting. Have you plugged the numbers into the site for your own estimates?

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe

This should confirm or refute the 3704 Kwh estimate. The site does seem to produce fair estimates from most reports.

12.56ppKwh seems high. If this is the rate that includes the standing charge then you need to use the straightforward unit cost for the calculation. If it is the rate that you are paying then it seems high. A quick comparison check shows rates for Edinburgh of between 9.5 and 10.5p. If lower rates are available then you should switch and use the new rate for comparison.

Why is the annual bill saving calculated at a rate of 15ppKwh - again I would have thought somewhere nearer 10p would be more appropriate.

I'm still very concerned that your useage won't match generation as closely as you would like particularly with regards to the conservatory. All in all I'm left with a slightly uneasy feeling.

Have you looked for another reputable company to provide a second set of figures? I know it's time consuming but worthwhile? It gave me a lot of confidence to have two companies come up with pretty similar figures.

[Deleted User]

Exiled_Tyke wrote: »

Very interesting. Have you plugged the numbers into the site for your own estimates?

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe

This should confirm or refute the 3704 Kwh estimate. The site does seem to produce fair estimates from most reports.

12.56ppKwh seems high. If this is the rate that includes the standing charge then you need to use the straightforward unit cost for the calculation. If it is the rate that you are paying then it seems high. A quick comparison check shows rates for Edinburgh of between 9.5 and 10.5p. If lower rates are available then you should switch and use the new rate for comparison.

Why is the annual bill saving calculated at a rate of 15ppKwh - again I would have thought somewhere nearer 10p would be more appropriate.

I'm still very concerned that your useage won't match generation as closely as you would like particularly with regards to the conservatory. All in all I'm left with a slightly uneasy feeling.

Have you looked for another reputable company to provide a second set of figures? I know it's time consuming but worthwhile? It gave me a lot of confidence to have two companies come up with pretty similar figures.

I think we will get another quote! The site whose link you gave me was the one I used that gave 3650 ... don't know if you saw the edit I put at the end of that post.

WR

Exiled_Tyke

Wild_Rover wrote: »

I think we will get another quote! The site whose link you gave me was the one I used that gave 3650 ... don't know if you saw the edit I put at the end of that post.

WR

Sorry I must have been working on my reply when you added the edit. That's good news then. Post up the details of the new quote when you get one. If it starts to look promising it might also be a good idea to let us know the precise kit they are proposing. There are some on here (not me) who may have opinions on the products.