Solar panels - piece of string questions

dave wrote:

My next door neighbour has just installed 50, very little spare room on the flat roof of his quite subsantial house, likely 25 squares.
And the individual panels are 1KW panels too.
That bugger doesnt do things by halves.

Varys with the panel.

Yes.
It isnt that hard to do a synchronised inverter.

Not clear if you mean a physical switch, obviously a relay etc.
There doesnt have to be a physical switch in that sense.

Depends on the environment. We can get some very spectacular dust storms so yes, you do need to clean them after that if you dont want to wait for the next rain to clean them.

Anything from a hose to a proper pressure washer.

Ours do. We mostly have evaporative coolers on the roof and the water works fine with them.
Australia.

Nope. They dont add much to the weight of a tiled roof and the strength of the timber used for a flat metal roof is determined by the wind loading, not the weight of the roof with a metal decking roof.

With a flat roof, there is a metal rail structure used to angle the panels properly. Thats just srewed to the roof structure with what we call tek screws.
With a tiled roof, there are still metal rails that the panels are mounted on and those are attached to the roof stucture in a similar way. Most of those panels are at the same slope as the tile, although strictly speaking its better to angle them up more than that.
There is also another massive great system that I walk past for exercise, out on the edge of town. Two great big square arrays that must be about 7x7 panels each tho I havent counted them. Each is on its own great steel column and each array tracks the sun right thru the day. Quite impressive to watch it start up at sunrise and shut down at sunset.

Nope.
Yep.
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Humm..
Middle England 53 deg..
Oz, 25 deg in the middle, should work quite well there;!...
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Tony Sayer



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tony sayer wrote:

And that can be a very long time between rain too.

Yep. Tho what that has to do with what you left of the quoting is less clear.
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tony sayer wrote

OK, it wasnt clear if what you left of the quoting was significant.

Yeah, but very few actually 'live' there.
The absolute vast bulk of people are in the SE corner and in a band along the coast from Townsville thru to say Adelaide, so there is in fact a very wide range of lattitudes.
Your soggy little island has a much small range of lattitudes.
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tony sayer wrote

Yeah, that smart arsed remark of mine has just produced a deluge over the bulk of that SE corner here. Didnt realise that usenet was so powerful.
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harry wrote

Yeah, thats what I meant.

Yebbut, some of those arent all that low rainfall wise.
We've just seen the end of a 10+ year drought, with plenty proclaiming that it was absolutely guaranteed to be the result of man made global warming.
Then we saw quite a bit of Brisbane under water when the fools that were responsible for managing the dam that was specifically built to stop that from happening, didnt bother to run it the way it was supposed to be run.
And Sydney has just seen its main dam overflow for the first time in 14 years, now that we spent billions on a desal plant for Sydney.
Needless to say, the fools in govt that built that desal plant were actually stupid enough to write the contract so that its still running at full capacity even now that there is much too much water in the main catchment and some have been evacuated because their houses are about to be flooded out.
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dave wrote:

Panels are actually rated by their peak output, and are typically in the range 100 to 260 Wp

The inverter is required to monitor the mains voltage and phase. Its control electronics takes care of it. There are mandatory requirements to be met by any installation connected to the incoming supply.

The panels will produce an output voltage whenever enough light falls on them. As soon as the output is sufficient, then the inverter turns on and produces ac output. This continuously varies.

Formal instructions say that they should be cleaned periodically. How necessary this is may depend upon the location and the nature of any contamination.
I guess that, as the number of installations increases, there will probably be firms appearing who will do this for a fee.

Not necessarily. However it would be prudent to get a written waiver from building control. I required my installer to take care of this.
OTOH a friend discovered his roof timbers had warped and were no longer properly supporting the roof weight. This required professional assistance and the addition of reinforcing steelwork.

Depends a little on the exact design of your roof. In my case the tiles were simply slid upwards to enable the stainless steel brackets to be secured to the roof timbers. The tiles are then returned to their original position. Mounting rails are fastened to these brackets, and the panels then bolt onto the mounting rails.
There is a great deal of information on the web, with photos, videos, output predictions and so forth.
Chris
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And of course if taking up the special offers you are restricted to a certain number of panels and that is it, unlike, it appears Australia and France, the latter where every seemingly available bit of space on farms has solar panels on them. Brian
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Panels are various sizes. Big ones are about 200Wattseach.

Google "grid tie inverter."

The panel is in parallel with the mains

No, they are self cleaning unless they are very flat/level.

Generally no.

Tiles are removed and brackets are screwed to the rafters. They are then cut & put back, sometimes with lead flashings.

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wrote:

Ta all. The GTI you mention is interesting. Senses phase to within 1 deg I see. Also a disconnect feature to protect line-repair men should there be a blackout - i.e to protect them from the inverter(s) output still being up. Being electrocuted by the Sun is a right bugger :-) http://en.wikipedia.org/wiki/Grid-tie_inverter
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<snip>
We looked at having a solar installation but with a maximum of 6 panels on the roof (mansard roof on a semi) the projected payback figures were too extended to make it a worthwhile investment. At the time (about 6 months ago) you needed about 10 to give a reasonable return, and going up to about 16 made the figures a lot, lot nicer.
Either things have changed dramatically or a lot of people are finding the same sort of cost/benefit a lot more attractive than we are. I suspect many are doing it because if you don't get it now the FIT will be cut right back, not because it makes sound economic sense.
Cheers
Dave R
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