Free solar panel discussion

Perry525

digitaltoast wrote: »

1: I wasn't talking about a slight overcast midsummer's day, I was talking about 5pm in December.
2: The production of solar PV under cloud is very minimal - about 20% of kwp at best.

As for the area varying only slightly, with a 1Kwp system in July in Newport, Isle of Wight, you'd get 123 kWh over the month.
In Glasgow you'd get 107 kWh over the month.

I'd say that was more than "slightly", over 25 years....

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Forgive me if I disagree..............
Newport Isle of Wight with a 4 kwh perfect setup will give 3785kwh per year on average December 102kwh December day average 3.3kwh.
Glasgow 3147kwh year Dec 61kwh day 2kwh
Not such a large difference, but will make a difference?

mrnomoneybags

Isis told me my roof area is too small

Jon_Tiffany

digitaltoast wrote: »

The top figure is what the company "giving" the panels get, the middle one is what the householder MIGHT save if they were in all day waiting for the sun to shine before turning on the washing machine, but what's the bottom figure?

The saving on electic bill assumes 50% useage of the generated electricity - from feedback from others that seems realistic.

If your meter spins backwards your electric bill saving will double to £360 and you will still get an assumed 50% export tariff payment of £45

The bottom figure is the export tariff payments at 3p per kW, assumed 50% export.

Dont forget that the company giving the panels had to raise the cash to buy the panels and will also be paying interest in the loan. The householder will have not paid any money, not have any risk.

In my opinion, if you have debt then buying your own panels is not a good idea, you should pay down debts first.

If you have spare cash in a low rate savings account, and you dont mind locking it into an investment then buy your panels.

You should be aware that if you buy your own panels your money is locked in. Someone else described it as like buying an annuity.

digitaltoast

Jon_Tiffany wrote: »

The saving on electic bill assumes 50% useage of the generated electricity - from feedback from others that seems realistic.

Well, no-one has taken up my challenge of "post your ACTUAL figures here" yes, so we'll have to take your optimistic word on that.

Jon_Tiffany wrote: »

You should be aware that if you buy your own panels your money is locked in.

You should also be aware that your roof is locked in. If some new technology 10x as efficient comes in in 5 years, you're still stuck with 16% efficient panels for the next 20 years.

Cardew

Perry525 wrote: »

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I am not at all sure, if the 4kw is peak rating, or the watts delivered at the meter. In a perfect setting you can expect to loose about 23 to 25%.

There seems to be some confusion between kWp, kW and kWh

The output of panels in kWp (in practice Wp)is rated under standard laboratory conditions with a known level of sunshine(illumination) temperature etc. The up to 4kWp allowance for the max rate of FIT is made up of x panels at, say, 185Wp.

Under those laboratory conditions a 4kWp array would produce 4kW of power, and in 1 hour 4kWh.

In much of UK a 4kWp array will not reach 4kW even under ideal conditions - late June at midday. However in, say, Cornwall it can exceed 4kW.

On MSE people with PV panels have remarked how little power(kW) is produced in the morning and late afternoon - the majority of power being generated either side of midday and of course far more in summer.

There are obviously power losses in transmission and the inverter, however the most important measurement is the kWh produced. This as stated above varies considerably according to location in UK. The further South the higher the annual output(generally)

Jon_Tiffany

digitaltoast wrote: »

Well, no-one has taken up my challenge of "post your ACTUAL figures here" yes, so we'll have to take your optimistic word on that.

You should also be aware that your roof is locked in. If some new technology 10x as efficient comes in in 5 years, you're still stuck with 16% efficient panels for the next 20 years.

Actually, my figures are rather pessamistic, and certainly realistic.

Just because no one has taken up your challenge doesn't mean it aint so.

If new tech comes in 5 years time you will only be getting 31.6p instead of 41.3 - the scheme takes account of improving technology. The reducing tariff is to stop people delaying getting the panels due to waiting for the ever improving technology.

And of course there is nothing to say that you cant replace the panels with newer ones, although I'm not sure how this would effect yout FIT rate and the extra cost would also somewhat ruin your ROI.

Anyone looking at investing in panels should also allow for one inverter to fail over the 25year period. I believe this was factored in when the scheme was designed.

digitaltoast

Cardew wrote: »

There seems to be some confusion between kWp, kW and kWh

The output of panels in kWp (in practice Wp)is rated under standard laboratory conditions with a known level of sunshine(illumination) temperature etc. The up to 4kWp allowance for the max rate of FIT is made up of x panels at, say, 185Wp.

Under those laboratory conditions a 4kWp array would produce 4kW of power, and in 1 hour 4kWh.

In much of UK a 4kWp array will not reach 4kW even under ideal conditions - late June at midday. However in, say, Cornwall it can exceed 4kW.

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. All you have to do is use the solar panel in an area where the insolation is higher than 1,000 W / m2. In other words most parts of the world that are less than 35 degrees latitude above or below the equator.

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...

Jon_Tiffany

DigitalToast, you are starting to get rather annoying, maybe that is your real aim? You are flooding this thread with some very poor maths and very misleading information, seem intent on disagreeing with everyone regardless and ignore the facts when it suits you.

What Cardew posted is completely correct:

Originally Posted by Cardew
There seems to be some confusion between kWp, kW and kWh

The output of panels in kWp (in practice Wp)is rated under standard laboratory conditions with a known level of sunshine(illumination) temperature etc. The up to 4kWp allowance for the max rate of FIT is made up of x panels at, say, 185Wp.

Under those laboratory conditions a 4kWp array would produce 4kW of power, and in 1 hour 4kWh.

In much of UK a 4kWp array will not reach 4kW even under ideal conditions - late June at midday. However in, say, Cornwall it can exceed 4kW.

digitaltoast

Jon_Tiffany wrote: »

DigitalToast, you are starting to get rather annoying, maybe that is your real aim? You are flooding this thread with some very poor maths and very misleading information

...says the snake oil salesman.

OK, perhaps you'd like to take 3 or so points I have made and show me where I am wrong, using actual facts and figures, and the url you got them from, as I have.

All I am seeing from you is someone who doesn't like a few inconvenient truths. I mean, facts? Figures? Why bother with all that stuff! Just blindly whöre your roof out for 25 years and science and economics be damned!

Would that be a correct summary of your position? As I say, no-one's proved me wrong yet, perhaps you can rise to the challenge? Let's start with your outright lie that you can generate more than 100% of kWp rated capacity in Cornwall...

Jon_Tiffany

digitaltoast wrote: »

...says the snake oil salesman.

OK, perhaps you'd like to take 3 or so points I have made and show me where I am wrong, using actual facts and figures, and the url you got them from, as I have.

All I am seeing from you is someone who doesn't like a few inconvenient truths. I mean, facts? Figures? Why bother with all that stuff! Just blindly whöre your roof out for 25 years and science and economics be damned!

Would that be a correct summary of your position? As I say, no-one's proved me wrong yet, perhaps you can rise to the challenge? Let's start with your outright lie that you can generate more than 100% of kWp rated capacity in Cornwall...

Ok, lets make one thing clear - I'm not selling anything, nor am I promoting the free panels offer.

My position is that I am about to have some panels installed (at my own cost) and I have spent a lot of time researching the subject.

I only respond to your posts because this thread is getting a lot of visits and its not right that misleading information is being posted.

I have supplied you with plenty of facts and figures, and have many times exposed the errors or distortions in yours.

It was Cardew who said that you can exceed the rated output, not me. Although, I do agree with him.