Reply to: The Dark side of the roof

[DallasDad]

What does that actually mean in practise? Does it mean, that in the best possible conditions, direct sunlight on the panels, they will be generating 4kw?
What sort of figures would they be producing on a grey, hazy day like today?
I'm interesting in getting some but I don't believe a word that the snake-oil salesmen say.

I have 4KW on my Bungalow.
I do not have a South facing roof so I have an East West Split, 8 panels on one side 8 on the other these are referred to as strings.
The two strings feed into a dual input inverter and they are aggregated together.

I personally never see a peak output of 4KW typically mines 3.5KW tops around midday in June.
I do get more duration though because each string is facing the Sun for longer than a South facing system would so the difference is maybe not as significant as you might think.
I get a good bell curve daily, right now it is 18:00 overcast and the system is producing 750W from the west string and about 150W from the east.
The Back ground use in the house is currently 300W so still earning money.

A good south facing system might produce 30KW per day on a good day I regularly get 20-25KW this time of year

I could have put the panels on A frames in my field but that needed planning permission and my sheep have a habit of butting things come tupping time so they would have needed protection. (the panels not the sheep)

I bought my system 4 years ago for £7k I am on the 21p per KW feed in tariff which pays out for 25 years, Mine will have paid for themselves probably by the end of next year so all the rest is pure profit. I have a couple of redundant 3KW Compaq UPS which I charge up during the day, as a result this time of year we hardly use any paid for electricity at all.
The trick is to use it all and export as little as poss washing machine on when the sun is shining etc.

Mine has proven a good RTI.
And if your meter goes backwards like mine did before it went smart the return is even better!

[vetran]

The solar panels are the equivalent of the petrol not the car. Efficiency is important when you have to cover your entire house with the things to provide enough energy for your household is my point.

'could be' - great but so far all our panels ARE using these rare earth metals. Until we find a replacement, efficiency in their usage is important.

And for most of that period, engine efficiency has not improved at any great rate. Again a direct comparison 'petrol is 20% solar is 20%' is rather pointless. On the one hand solar energy is effectively limitless whereas petrol is limited, on the other hand solar requires a lot of space and materials and cost. They're fundamentally different - we don't use petrol engines to heat our homes or power factories, we don't use solar panels to power our cars. THe thing about petrol is it is such a high-density, incredibly portable form of energy.

In the UK, doubtful

The hybrid stuff is hugely increasing efficiency even in the same chassis - energy recovery from heat and under braking, etc.[/QUOTE]

where is the filler cap on Solar panels? The cost of the car is entirely relevant as there are no running costs on solar panels there is no Solar Gasoline. If you want to go down the running cost only route lets try that.

http://www.theaa.com/resources/Docum...petrol2014.pdf

£5126 per year at 10,000 miles a year.

Solar is £5k over 20 years.£250 / year.

Non rare earth ,Its possible, as it becomes profitable it will be come the standard.

Nope as above cost is a minor factor. space is 21 square metres, My cabin has more roof than that.

[VectraMan]

45-50% for an F1 car, and not just because of the hybrid malarky:

Why an F1 car is more energy efficient than an electric car

Petrol not quite dead.

[vetran]

If a tank of it expodes, your house will be level - with the ground!

nope otherwise ford would be calling their new Hydrogen cars the HydroPinto

Here's why hydrogen-fueled cars aren't little Hindenburgs | Computerworld

The hydrogen fuel cell tanks in the Toyota Mirai are pressurized up to 10,000 psi, and hydrogen is 16 times lighter than air. So, if a tank were punctured or otherwise compromised, the hydrogen gas would instantaneously dissipate into the atmosphere, Hartline said.

John Kopasz, a scientist at the Argonne National Laboratory who performs research on hydrogen gas production, said that while there are inherent dangers with any combustible fuel, hydrogen fuel is safer than gasoline.

If a regular car's fuel tank is punctured, gasoline leaks out and pools beneath the vehicle, creating a ready source of fuel for a prolonged burn, Kopasz said.

In fact, in the case of the hydrogen-filled Hindenburg, most of the fire was fueled by diesel fuel for the airship's engines and a flammable lacquer coating on the outside of the dirigible.

Today's hydrogen fuel tanks are also made from highly durable carbon fiber whose strength is assessed not only in crash tests but also in trials in which bullets are fired at it.

[Hobosapien]

So they use prisms to bounce the light around until it is absorbed by the panel.

So for storage, stick a lid on the prism with a hole and a magnifying glass pointing at the hole to get the light into the prism storage unit. The angles of the prism mean the light never bounces back out through the hole. The longer the prism the more light it can trap awaiting absorbtion, which will be at a constant rate so you have storage in the meantime.

No need to overcomplicate things.

Anyone patents it and this message is proof I came up with the idea first. Cheque please.

[OwlHoot]

Hydrogen looks interesting at a house level ..

If a tank of it expodes, your house will be level - with the ground!

[Chuck]

£5k for a 4kw installation

What does that actually mean in practise? Does it mean, that in the best possible conditions, direct sunlight on the panels, they will be generating 4kw?

What sort of figures would they be producing on a grey, hazy day like today?

I'm interesting in getting some but I don't believe a word that the snake-oil salesmen say.

[d000hg]

£5k for a 4kw installation, I suppose you could buy half of a fiat 500 for that.

The solar panels are the equivalent of the petrol not the car. Efficiency is important when you have to cover your entire house with the things to provide enough energy for your household is my point.

Non rare earth
New solar panels made with more common metals could be cheaper and more sustainable - American Chemical Society

'could be' - great but so far all our panels ARE using these rare earth metals. Until we find a replacement, efficiency in their usage is important.[/QUOTE]

The point was to convey a sense of achieved efficiency by comparing technologies. Comparing a technology in its infancy against that which is 120 years old says a lot imo.

And for most of that period, engine efficiency has not improved at any great rate. Again a direct comparison 'petrol is 20% solar is 20%' is rather pointless. On the one hand solar energy is effectively limitless whereas petrol is limited, on the other hand solar requires a lot of space and materials and cost. They're fundamentally different - we don't use petrol engines to heat our homes or power factories, we don't use solar panels to power our cars. THe thing about petrol is it is such a high-density, incredibly portable form of energy.

I think society is more likely to be absorbing the benefits of solar technology than F1 technology. But that's just my opinion.

In the UK, doubtful

Actually I think we are seeing benefits from F1 technology and a greater concentration on fuel efficiency. Automatic cars are now more fuel efficient than manual something that was driven by racing. Fuel economy ad lightness (carbon fibre) also are slowly appearing. Cars that do more than 15 miles to the gallon.

The hybrid stuff is hugely increasing efficiency even in the same chassis - energy recovery from heat and under braking, etc.

[OwlHoot]

I thought 34% sounded a bit too good to be true, given the theoretical limit on solar cell efficiency of about 33% which I vaguely recalled.

But it turns out this so-called Shockley–Queisser limit applies only to a single "layer", and can be far exceeded by stacking layers.

[scooterscot]

Actually I think we are seeing benefits from F1 technology and a greater concentration on fuel efficiency. Automatic cars are now more fuel efficient than manual something that was driven by racing. Fuel economy ad lightness (carbon fibre) also are slowly appearing. Cars that do more than 15 miles to the gallon.

Which is great. Especially if there is a future for internal combustion engines. I'm part of the belief that be the end of my generation or certainly the next will see them confined to museums.

[scooterscot]

But solar energy is far more diffuse, and the equipment needed to gather it far more expensive - and relies on rare resources. So it's not quite the same thing - you don't need high efficiency when petrol is so energy-rich and you can just top up the tank in a few moments (until we run out of course)

Jeepers creepers. All new technology is expensive.

I'm all for growth. If the country if to compete with east we need to build smarter, be innovative and invest. Fine tuning yesterday's tech is not going to do that. If government had more than one scientist they'd might understand where our priorities exist. Heck we might even attract home grown engineering graduates.

[vetran]

Without needing huge tanks of pressurised liquid oxygen or hydrogen or something, which any half competent terrorist could easily turn into a giant bomb!

Hydrogen looks interesting at a house level , imagine cutting your gas bill as well.

[vetran]

The point was to convey a sense of achieved efficiency by comparing technologies. Comparing a technology in its infancy against that which is 120 years old says a lot imo.

I think society is more likely to be absorbing the benefits of solar technology than F1 technology. But that's just my opinion.

Actually I think we are seeing benefits from F1 technology and a greater concentration on fuel efficiency. Automatic cars are now more fuel efficient than manual something that was driven by racing. Fuel economy ad lightness (carbon fibre) also are slowly appearing. Cars that do more than 15 miles to the gallon.

[OwlHoot]

Anyone who can crack storage is going to be SOOOOOOO rich

Without needing huge tanks of pressurised liquid oxygen or hydrogen or something, which any half competent terrorist could easily turn into a giant bomb!

[scooterscot]

So what? Genuinely what point are you making?

Also, the downstream impact of modern F1 technology is going to make a big difference here. I think they're at 53% now.

The point was to convey a sense of achieved efficiency by comparing technologies. Comparing a technology in its infancy against that which is 120 years old says a lot imo.

I think society is more likely to be absorbing the benefits of solar technology than F1 technology. But that's just my opinion.