Free solar panel discussion

Jon_Tiffany

You wanted some real figures? They are available right here on this forum:

https://forums.moneysavingexpert.com/discussion/1838505

I've had 8 x 180w Sharp Solar PV panels on my roof for one year now.
I see a lot of questions from people asking if they are worth it, so I think it is time I created a post from someone who actually has them.

Initial Cost: £7950
Grant: £2500
Remainder to be paid by me: £5450

Units generated in one year: 1186
Units predicted by installers: 1130
Units used by house: 3870
% covered by solar panels: 30%
Amount saved off bill (assuming each unit is 15p): £177.90
Payback assuming everything stays the same: 30.6 years
Warranty on panels: 25 years
Life expectancy (albeit not all covered by warranty): 60 years

With my current setup, my meter spins backwards during daylight (assuming I'm not in the shower, or ironing/hoovering)
However, I have applied for Scottish Powers solar tariff where I get 28p for every unit I export.
This changes the numbers as follows:

Units generated in one year: 1186
% exported: 50% (estimated)
Scottish Power payment: £166.04
Amount saved off bill (for my own use of panels): £88.95
Annual saving: £254.99
Payback assuming everything stays the same: 21.37 years

From April next year, I will qualify for the UK Feed-in-tariff.
This pays 36.5 for every unit I generate (whether I use it or not)
WARNING - not all technologies qualify for the 36.5p - don't assume that if you generate electricity by another method, you get such a high payment

Units generated in one year: 1186
Feed-in-tariff: £432.89
Amount saved off bill (assuming each unit is 15p): £177.90
(You'll still be saving any electricity off your bill as in the first estimates)
Annual saving: £610.79
Payback assuming everything stays the same: 8.92 years

People often ask about maintenance on PV solar..
It is nil, absolutely nil.
Bird poo goes on, bird poo washed off by rain.
They get dusty, they get clean in the rain again.
I've not attempted to clean them, but if I really wanted to, a hosepipe would easily be able to get them from the ground.
I hope this answers any financial related questions regarding my solar PV panels, but if you have any more, please send them through.

furndire

If you don't mind me asking, which area, roughly, are you in Jo?

digitaltoast

Jon_Tiffany wrote: »

You wanted some real figures? They are available right here on this forum:

https://forums.moneysavingexpert.com/discussion/1838505

And as it says later in that thread...

Cardew wrote: »

I am sorry but this is where your calculations are absolutely wrong.

As I said above you simply cannot ignore the cost of borrowing the £7,550 or the loss of interest on that £7,550.

It is like saying I have a £100,000 mortgage at 6% interest and if I pay £5,000 per year it will be paid off in 20 years.

As said earlier £7,550 invested at 5% will realise £377.50(which will be compounded) and every likelyhood of rates increasing. It will cost you a lot more than that to borrow £7,550. You have to deduct those costs from your savings

So even assuming that your feed in tariff remains that high(doubtful) you are talking of a payback period of some 50 years. which makes the reports you have seen in the press about correct.

The other issue is the system guarantee. Only 2 years is a lot different to 25 years. It is inevitable that with cables, connectors and electronics that there will be failures and considerable costs to remedy. If it were not expected to have failures why ony a 2 year guarantee.

If it is like much of the 'small print' on solar I have seen they require an annual inspection.

We might have to agree to disagree!:beer:

Looks like someone forgot to calculate in the cost of failed inverters too. And taking them off and putting them back on again when roof work needs doing.

Sorry, I'm doing all that inconvenient "real world" stuff that irks you so.

Mcfi5dhc

digitaltoast wrote: »

And as it says later in that thread...



Looks like someone forgot to calculate in the cost of failed inverters too. And taking them off and putting them back on again when roof work needs doing.

Sorry, I'm doing all that inconvenient "real world" stuff that irks you so.

And if you keep on reading that thread, you'll see I have factored the cost of a new invertor in. I haven't factored in the cost of a new roof, because my roof is already newish

Jon_Tiffany

digitaltoast wrote: »

And as it says later in that thread...



Looks like someone forgot to calculate in the cost of failed inverters too. And taking them off and putting them back on again when roof work needs doing.

Sorry, I'm doing all that inconvenient "real world" stuff that irks you so.

In post 427 I said:

Anyone looking at investing in panels should also allow for one inverter to fail over the 25year period.

Jon_Tiffany

Cardews old post about allowing for interest on loans is correct. That is why in my opinion you should not buy panels if you have to borrow the money.

I disagree with Cardew on the payback period, it should be 6-10 years for most people, depending on how good a deal they get.

Trying to give a balanced view, a plus side of the free panel offers is that you do not need to worry about return on investment, payback time, failed invertors etc. But in return for the reduced risk, the benefit will be lower.

But once again, I am not promoting the free panel offers, just saying that for some people the offer will make sense, while for others it makes more sense to invest yourself.

digitaltoast

Jon_Tiffany wrote: »

In post 427 I said:

Anyone looking at investing in panels should also allow for one inverter to fail over the 25year period.

http://solarcost.org/solar-inverter.html

Depending on its type, the lifespan of a solar inverter may vary from 5 years to 15 years.

At £1,600 per unit (at today's prices), how does that affect your calculations?

Mcfi5dhc

dapri wrote: »

You will have received a lower bill due to the meter running backwards so you will have received a refund by default !

I wrote the above bit because some people questioned whether they should ask for a refund or not - clearly my bills were lower

dapri wrote: »

Even if the meter does run backwards during periods of peak PV generation - it will resume forwards running at night - or at least when the home's demand is greater than the available PV so net result is you will be charged for the balance of energy which you will have been seen to consume.

Correct

dapri wrote: »

The backwards running meter is a small additional (often un-expected and short term) benefit

This is incorrect - the benefit of a backwards running meter is considerable, especially for the audience of people thinking about a free solar PV system.

If you have a backwards meter, you will get the full benefit from everything generated. Sometimes it will be going forwards, sometimes backwards, sometime staying still even when you are using power. In affect, you are being paid approx 10p per unit when you are exporting (meter going backwards)

However, with an export meter, you only get paid 3p a unit for exporting which eon, npower et al sell on for about 10p.

For those on a freebie, with a backwards meter, their bill would be roughly 3000 units less after a year which would clearly be used for any use the homeowner wanted and at any time of the day, or season of the year. With an export meter, they would probably be able to use 15-50% of the 3000 units, therefore having to pay for more (though still less than if they didn't take out the freebie panels). They would also have to use timers, or good timing to make the most of it

So the moment freebie people get a smart meter, or an export meter, their bills will only reduce by maybe £50-£150 a year, compared to £300ish if their backwards meter stayed the same.

Clearly though, if they had a new meter already, it won't make any difference, and they would just get the benefit of £50-£150 a year

Jon_Tiffany

A simple way to look at it is that it could extend your payback time by 1-2 years. This is not as simple as it seems as it depends on where in the 25years the inverter fails. If it fails at 6years is very different to it failing at 24years.

The government factored in the cost of failed inverters and they predicted that you should get around a 8% return.

Cardew

digitaltoast wrote: »

I beg to differ there, and I wonder if you can point to the URL you get these figures from?

http://www.solar-facts-and-advice.com/kWp.html

The specific testing conditions are specified in standards such as IEC 61215, IEC 61646 and UL 1703; specifically the insolation level is 1,000W/m2, with a spectrum similar to sunlight hitting the earth's surface at latitude 35°N in the summer (i.e., perpendicular to the solar panel being tested). A standard airmass of 1.5 and temperature of the cells at 25°C is also assumed.

Note: Just like its possible to boost the horsepower of a car above the nominal rating, it's also possible to produce more electricity than the so-called Peak Power rating

A quick look at google maps will show you that Cornwall is way off that at 49 degrees, but if you'd like to run an extension lead from Tunisia or Syria to get those figures, be my guest...

Doesn't your quote itself offer up the possibility that you can exceed the so-called peak power rating?

This is a quote from yakky58(who lives in Hampshire) - if you read his posts you will see he makes a lot of sense in all his posts, and is not given to making wild claims - like so many with systems.

Hi back after the retirement from meaningful work.

June 2010 just finished and was the best month ever 306 kwH generated and 155 of those exported.
I did clean the panels in May I am not sure if that accounts for much but my reasoning is bird droppings could affect the generation as could accumulated dust and grime. Anyway best month ever!

I checked on my inverter, a Fronius which captures all sorts of data one being highest generation... that is for a 5 minute period. Mine is 2156 watts which is over the rating for the panels.... 10X 205w = 2050 watts. Unfortunately it doesn't capture when that happened.

I have calculated my FIT for April/May/June quarter 844 kwH generated and 497 exported. So around £90 to come back when SSE get their act together.

You will note that his highest output from a 2.050kWp system was 2.156kW albeit for 5 minutes. So it is perfectly reasonable to state that Cornwall could also exceed the rated kWp output.

Indeed someone in Yorkshire with one of the ASG 3.3kWp systems stated in the thread that he got a peak reading of around 3kW.