OT: More bad news for harry...

[The Natural Philosopher]

In winter my house used to take 10KW just to keep warm.

[tabbypurr]

What I actually said was:

ouse. The trouble is all the equipment needed to make use of a small fracti on of it.

To put it another way, it's not the PV harvest that's enough, it's the amou nt of energy in the insolation.

According to the CIA, UK uses 622W per person. This is the average power us e 24/7/365, and covers all uses. What portion of that is domestic I don't k now.

A typical 2 storey 1000sqft house has 500sqft of upstairs ceiling = 50m2. If we had the ultimate in PV we could count all insolation falling on all sides of the roof, ie on 50m2 of flat area for not too steep roofs. So to r un this house we'd need 622W/50 = 12.5W per m2 on average, 24/7/365. Inso lation in the UK is an order of magnitude greater than that, so there's cer tainly enough energy there in the insolation.

What is needed is the ultimately efficient ultimately cheap harvesting mech anism.

I doubt battery will be the way to go. It's too inefficient in energy, mate rials, space & cost. Some sort of storage is needed of course. If the techn ology ever gets there, we don't know what form it will take.

NT

[Dave Plowman (News)]

Quite. And you can be sure those wanting to make a point on either side will fiddle them to prove what they want it to.

If you're going to work out the overall worst case carbon costs of solar, you'd also need to remove the worst case carbon costs of generating the electricity it replaces.

[Chris Hogg]

Info on annual domestic electricity consumption, by postcode, given in the links on this govt site

. Also, the mean annual domestic electricity consumption per meter in Great Britain was 3,954 kWh, from the pdf file linked to here top of page 11.

Of course, they're over a year, day and night. For roof-top solar panels or PV roof tiles to make a sensible contribution, some form of local storage would be necessary. Harry has a battery in his car, which doesn't contribute significantly to his domestic electricity use but does cut down his petrol consumption which, if you're into over-all CO2 reduction and have rejected nuclear, at least makes a contribution to that end.

[Chris Hogg]

As an aside on Euarn Mearns' site, I see he's hosting an ad for KiteGen. Even allowing for the fact that I don't really grasp how you're supposed to extract meaningful amounts of energy from them, it seems to me that having a forest of kites all waving around and bobbing up and down in any one area is no more sensible than a forest of windmills, and subject to similar disadvantages.

[dennis]

Its worse than that..

there are several types of solar PV panels ranging in efficiency from about 8% to about 18%.

The energy input to making them is similar so the energy payback on the

8% panels is much worse than on the better ones.

However the 8% ones are dirt cheap from China so nearly all the installations use them and they almost certainly never pay back the energy used to make them.

The better ones may just pay back depending on where they are installed.

You can guess which ones harry has and it is going to be the cheapest going as it will be on any that are installed for "free".

They probably don't even care about the efficiency of the inverter as long as they get their 4kw FIT payment.

[dennis]

If you are on the current FITs you only get 4.5p for exported power so why do you expect more?

[Chris Hogg]

Ah...put that way, nor can I. I rather assumed that by hosting their ad he was implying tacit endorsement of their technology.

[The Natural Philosopher]

I don't think so!

Not if my conversations with him are anything to go by!

[Mike Tomlinson]

En el artículo , The Natural Philosopher escribió:

That was my thought too. Take the money, run the ad, let people point and laugh if they want.

[dennis]

He may not control what ads he gets. Quite a few "companies" will pay you to put a banner on your site but the content comes from their servers and you only get a bit of say in what they are.

[dennis]

I think you are optimistic. I think a 1kw array will net you about 300 kw hrs a year, most of that in June-September. You might manage a bit more if you can steer the array. So unless your house only has a couple of LED lights you have no chance of running it.

Waits for harry to claim its saved him half his energy when he means its halved his bill and saved bugger all energy.

[dennis]

Have you tried it with the doors shut?

[harry]

In Winter my house needs nothing to keep warm for 95% of the time. The PV is only part of the solution.

[bert]

+1

[harry]

Half a million years?

No, the reason is they don't know how. So they kick the problem into the long grass. But the pigeons are just starting to come home to roost.

The frogs have discovered this too.

[bert]

And in the meantime?

[bert]

And how will they be decommissioned? By chucking into landfill along with all the cfl light bulbs.

[Tim Streater]

Not when you need it though. I need it quite a lot at night when its dark, especially in the winter.

Why is it so difficult to make klods understand that in winter, when it's dark and cold, you have bugger-all solar energy?

[The Natural Philosopher]

IT was a BIG house.