solar tiles

[Greg.hart]

anyone seen these before have any opinions?

Whilst i know the payback will be even worse than other methods but thinking that they may be more LBC friendly.

http://www.marleyeternit.co.uk/Products/ProductDetails.aspx?pcat=1&pcatname=Tiles+%26+Slates&rangeid=12&rangename=Solar+Tile&pid=54&prodname=Solar+Tile

 

[Nemesis]

I rather think that they will require more than a few to get much benefit - hardly historic roof friendly really.

 

[NT]

Are you off grid? If not I'd forget PV.


NT

 

[MdB]

Why do you want to fit them? Is it because you think it will help the environment and "doing the right thing"?

If so, take a careful look at the cost of the installation and the value of the electricity it generates. In rough terms, the energy required to produce the tiles in the first place is equal to the cost of the tiles (if you factor in all of the energy involved in their manufacturer and installation including labour). If the tiles won't generate the energy used to produce them in the first place then fitting them is decidedly ungreen. Not that the manufacturer will admit to this.

Having said all of that, PV cells are getting better all of the time and the costs keep coming down so they may now be at the stage where they are worth fitting. It would be interesting to see the figures.

 

[Nemesis]

I doubt very much that any CO with much about them will allow removal of a swathe of historic listed roof and replacement with these!

 

[Gervase]

They're in the same league as David Cameron's Notting Hill windmill - fitted for show not for blow.

 

[Greg.hart]

Just curious really. I have a extension with man made slate tiles (done in the 70's) which are pretty nasty and as we don't have gas, (and due to the possible locations of a boiler I think getting a gas CH system might be out of the question), so am looking at something to sit in a electrical hot water / heating system to provide some extra heat / electricity during the day. Not so much about being green really more about trying to minimise the running costs.

Was thinking PV's but don't think there is a suitable location in the garden (We have very tall garden walls and some tall buildings surrounding us and so the only place that would be suitable would be on the roof and thought these might be more possible Council wise.

Hey ho back to the drawing board

Specs which seem optimistic.

Size 773 x 420mm
Effective cover (75mm lap) 735 x 345mm
Roof area coverage 0.25m²
Laid weight 40 kg/m²
Output 23 Wp (watts peak)
Output/m² 0.92 kWp/m²
Short circuit current 5 Amps
Open circuit voltage 6.1 Amps
Maximum power point voltage 5 Volts

 

[MdB]

Well those figures don't make sense....

735mm x 345mm = 0.25m^2
Per panel output of 23Wp gives a figure of 0.092kWp/m^2 which is a factor of 10 out compared to the figure they give. Also open circuit voltage is measured in volts rather than amps. Doesn't fill you with confidence does it...
From the current and voltage figures is looks like the 0.092kWp/m^2 is correct.

Lets assume the panel gets 8hrs of peak sunlight per day, 365 days per year (very very optimistic). This means that the 1 square m of panel will generate 0.092kW x 8 x 365 = 268 kWhrs of energy per year. At the generous price of 15p per kWhr, this means each square m of panel generates £40 of electricity per year if sun conditions are ideal.

Unfortunately, the UK is not well known for bright sunlight every day of the year so I would divide this figure by at least 4 (2 hours of maximum sunlight per day, every day) or maybe even more.

Cost is not mentioned on the site but if it is less than £1000 per sq m then I would be surprised. Pay back would be 100 years minimum.

These tiles are decidedly ungreen.

 

[NT]

If you amortise the cost of PV over its lifetime, the cost is well above buying grid power, so there are no savings to be had. The only time it makes sense is when connecting to the grid would be monstrously expensive.

The one type of alt power that makes good financial sense in some cases is solar air heating, which works through the winter.

A little info here:
http://wiki.diyfaq.org.uk/index.php?title=Solar_Thermal


NT

 

[Greg.hart]

The more I look into it the more I'm coming to that conclusion. I just hate storage heaters and am looking for a alternative...

 

[NT]

ac units used as heat pumps will give considerable cost savings compared to storage heaters, but their performance declines badly at low outdoor temps, so they are only partial heating solutions.


NT

 

[AMc]

You can buy real green electricity from http://www.good-energy.co.uk which will be cheaper unit for unit than anything you can microgenerate yourself using solar PV.

If you still want to go ahead also look at these products which have an intergrated system for solar water and/or hot water. Solar hot water is generally more cost effective.
http://www.solarcentury.co.uk/products/

But really bear in mind

A PV roof will cost between £6,000 and £7,000 per 'peak kilowatt' (the maximum output). However, through the Low Carbon Buildings grant scheme you should be able to claim about half of this. A 1 kilowatt (1kW) system will cover about 10 square metres, and produce about 750kWh (units of electricity) over a year - mostly in the summer. As 1kWh of gird electricity costs about 10p, this annual output would offset about £75 - so you can see that the payback time is currently quite long. See our 'Introduction to PV' factsheet for detailed advice about solar photovoltaic systems.

http://www.cat.org.uk/information/catinfo.tmpl?command=search&db=catinfo.db&eqSKUdatarq=InfoSheet_GridConnected

If you want to be green then insulate the room to minimise space heating needs first.
If you have 70's single glazing then look at a new double glazed unit - they don't have to be uPVC
Seal drafts to minimise ventilation heat loses (but be careful of ventilation for any gas heaters, fires etc.)
If you have a central heating radiators fit thermostatic valves to heat spaces to the right temperatures.
Keep the temperature sensible as the greater the difference between inside and outside the more energy you will lose.
And put on a jumper if you're cold - that's the most effective place for Sheeps wool insulation

I use an electric fan heater in my office in the day in winter as heating one room when it's occupied is more sensible than heating a 4 bed house even though it's less efficient than my oil fired boiler.

 

[Greg.hart]

I have a steadily growing supply of jumpers and actually much prefer colder houses to live in and generally just have background heat for the majority of the flat with a convection in the living room when required. The Other half has different thoughts on this but she's not winning the argument at the moment.

We're a bit tied with the fact it's 18c GII listed and so it really cuts down your options re double glazing, AC units etc. (although I was told about double glazing units which sit in between the glazing bars - very expensive and do wonder what they would look like!)

We also have a solid floors and would need to position the boiler for central heating at the rear of the property. would entail a lot of digging or ugly boxing in.

The more I think about it the more a system along these lines seems to be the most suitable option for hot water and heat and then possibly leave it in a position to add solar water heating etc at a later date.

http://www.gledhill.net/water-storage/ws-index.htm