Free solar panel discussion

Gizmosmum_2

The point is that the roof has to withstand the panels + that freak 80's storm and the snow - not just the snow. Sounds to me like ASG are quite switched on....

ronlizpatsimon

barneygumble wrote: »

When we applied we were told by a shade greener's structural engineer that our roof didn't have sufficient capacity to withstand a solar panel installation. When we had all the snow in winter I would wager there was far more weight in snow than the panels themselves would weigh. I wonder what factor of safety the engineers work to?

As they refused your business, they must have been convinced that it was unsafe to install it.

Uncompacted snow is quite light.

zeupater

ronlizpatsimon wrote: »

As they refused your business, they must have been convinced that it was unsafe to install it.

Uncompacted snow is quite light.

Hi

A moderate single snowfall of around 6" over the area of a 4kWp array will add somewhere around 1.5 tonnes to your roof. The panels and mounting frame would weigh up to 0.5 tonne. This weight would effectively be point loaded through the mounting brackets.

HTH
Z

Cardew

zeupater wrote: »

Hi

A moderate single snowfall of around 6" over the area of a 4kWp array will add somewhere around 1.5 tonnes to your roof. The panels and mounting frame would weigh up to 0.5 tonne. This weight would effectively be point loaded through the mounting brackets.

HTH
Z

The same tonnage on snow on the North facing side of the roof as well?;)

zeupater

Cardew wrote: »

The same tonnage on snow on the North facing side of the roof as well?;)

......

You've got it in one ...... the difference being that the load is spread more evenly across the total roof structure by the battens being connected to all of the rafters, whilst the panels would likely be supported by a couple of dozen brackets which are not connected to all of the available rafters, effectively creating point loading.

If we were talking about a weak roof for a purchased system a structural engineer would likely recommend using more roof hooks or strengthening the roof structure using a combination of purlins, ties and props. However, for 'rent-a-roof' companies any extra cost is lost profit, which on 'fixed' income such as FiTs cannot ever be recovered ... they just pick the low hanging fruit as that's where the profit is to be maximised.

Z

digitaltoast

Does anyone REALLY believe the FiT's will last as they are, increasing at the rate they are, beyond about 5 years time?

Here's the webpage from a BBC show called "Costing the Earth":
http://www.bbc.co.uk/programmes/b0100grj

Birmingham City Council is already fitting solar to 10,000 homes and farmers with more than 35 acres had hoped to earn as much as £50,000 a year harvesting solar energy. But, the government now seems to be backtracking on its promise of large subsidies. Spain's solar industry recently crumbled due to the false economics of government fundingand they have a lot more sunshine than the UK . Germany too, which has the world's largest market for solar, has recently had to dramatically decrease promised feed in tariffs in order to prevent an unsustainable bubble.

I don't feel it asked enough tough questions, but it certainly shows this madness is unsustainable. If FiTs take off in the way people want them to, and let's say one in every 4 houses has panels, then by the virtue of basic maths the electricity bills of the old, the poor, the underclass without large south facing properties they own, will be roughly quadruple.

You really think any government of the time will be able to sustain that given the rioting there will be over this?

Second reason for me posting today: last night I spoke to an engineer who knows a helluva lot about coal fired power and turbines.
As I suspected and also as mentioned on wikipedia, the idea that you can "wind back" the amount of coal fired power needed when the sun pops its head out is pure nonsense and fantasy. The complete system of a coal fired station is designed to run at one speed and that's it.

He's going to email me something, I'll post it here when I get it.

John_Pierpoint

I heard that programme too.
That guy who set up the Glastonbury festival does not miss a trick.

What makes you think the tax and subsidy system won't last.
The common agricultural policy has been doing just that on a much greater scale than the FiT ever will, since VAT was introduced.
I've not seen riots in the streets yet.

The programme glossed over the figures, only accurately stressing the payments available for the large scale systems.

Just wait for the subsidies for decommissioning the remaining nuclear power stations following the little local difficulty in Japan.

Moist_von_Lipwig

Germany too, which has the world's largest market for solar, has recently had to dramatically decrease promised feed in tariffs in order to prevent an unsustainable bubble.

Isn't this just for new installations? This is already planned for the UK.

Systems installed after 31st March 2012

The FiTs will apply to all new eligible systems installed. However, the FiT rates will decrease for systems installed after 31st March 2010. There will be a decrease in the FiTs for systems installed from April 2012, a further decrease for those installed after April 2013 with continued cuts each following year.

John_Pierpoint

It was always planned to work something like that.
You have to offer "prime mover advantage" to get a new industry off the ground, but offering inflation proof income (currently worth an extra 5% each year ????) on to of the national annuity yield caused a tsunami of "smart money", when the banks were offering 1 or 2%

If we all did it the local grid would not know what to do with the power surges anyway.

Doc_N

Moist_von_Lipwig wrote: »

Isn't this just for new installations? This is already planned for the UK.

That's my understanding, too. These weren't cuts in tariffs already in payment, but cuts in tariffs for those who hadn't yet 'signed up'.

The UK FITs aren't exactly open-ended, and the take-up levels are being monitored. They can be pulled at any time, or adjusted, as they have been already, if things start looking problematic. There should be no need to amend FITs already in payment - any impact just isn't sufficiently material, unless there's a flood of applications, and that can be controlled by an adjustment to tariffs before the event.