PV- Is there a business case ?

[ColJack]

BAS,
I'd be interested to hear of a solar thermal system that works at night( I'm making an assumption you meant when dark).

ok, lets see..

you have a big radiator outside painted black, it's ( for arguments sake ) 15°C overnight and you're pumping water through it that is ( again for arguments sake ) at 10°C.. you don't think that the water is going to absorb the ambient heat?

Brainwave!!!!
I'm envisioning a system similar to an air source heat pump, but where the evaporator coil is laid out flat and put under glass.. surely you'd get a lot more heat out of it that way than just pumping cold water through the panels?

 

[ajstoneservices]

Col,
You've just re-invented the wheel. At it's simplest, what keeps the heat in, keeps the cold out.That's the difference between night and day.



Bas may have the answer.

 

[ajstoneservices]

Years ago, before the intenet, I read an article that some research place in the uk had tried all sorts of solar power/heat sytems.

They reported that the most efficient system in terms of capital cost and return was a garden hose looped on plywood and sprayed with matt black paint.

Some years back that would have been true, then came building regs and put paid to that.

 

[ajstoneservices]

The powers that be decided that only solar collectors that have been tested to EN12975parts 1 & 2 as a minimum can be installed(what they don't know cant)

To qualify for any grant or future RHI they will need to be Solar Keymarked.

 

[ban-all-sheds]

BAS,
I'd be interested to hear of a solar thermal system that works at night( I'm making an assumption you meant when dark).

I said "to some extent".

I was assuming that if you're circulating fluids through pipes or panels which are at a higher temperature than the fluid, the fluid will increase in temperature, because unlike photo-voltaic it's not worked by light, it's a thermal thing.

But it could be that it doesn't work like that....

 

[Stoday]

Chri5 is not far wrong when he estimates 5 hours of sun per day, 365 days a year.

You can download weather data from the weather centre at Royston http://www.iceni.org.uk/.

The average number of sunshine hours per year for the nine years 1999 to 2007 incl., at Royston, is 1685.

 

[londonboy]

Remember its not sunshine the solar pv needs, its 'Irradiance', which is different to lux and measured in watts per square meter.

Also the panels should be mounted at 30 degrees for optimum output, you can get 'buckets' (essentially a plastic frame) for the panels to sit in.

 

[Chri5]

Curve ball being the Royston data

So where would I look for performance data regarding PV panels and what a sunshine hour produces in watts via a panel ?

It would seem a tad unsafe to assume that 5 sunshine hours = 5 hours of 175w output on a 175w panel.

 

[londonboy]

This website gives you the Irradiance levels:
http://mappery.com/United-Kingdom-Solar-Radiation-Map

Remember the watts quoted for the panels are kWp (kilowatt peak).

So a 1kWp solar pv system will, on average, produce around 750kWh of electrical energy per year.

Generally a 2kWp system can provide up to 40% of your total useage.

 

[bongos]

I still can't see that PV is a viable way to spend your money. Spend £15k on a wind turbine in the Atlantic.

 

[Stoday]

As gsaschedule has bumped this year-old post up I thought I'd add something.

Someone mentioned that the payback was "9 or 10 years".

That's a dreadfully poor investment. You could put your money into Chelsea Building Society now paying 3.1% and get a better return over any number of years. After 25 years, with a £1000 PV investment you will have paid off the £1,000 put £1,500 in your pocket and have a now worn-out PV system. However if you invested £1,000 in the building soc your account after 25 years would total £2,145.

 

[ban-all-sheds]

When comparing rates of return people often seem to forget the fact that with a PV system your capital has been lost, whereas with a savings account it's still there.

 

[riveralt]

When comparing rates of return people often seem to forget the fact that with a PV system your capital has been lost, whereas with a savings account it's still there.

This article should, but won't, set PV on the road to oblivion.....

http://www.telegraph.co.uk/earth/en...ting-rip-off-exposed-by-undercover-probe.html

 

[ban-all-sheds]

Which? said two firms, Everest and Ideal Solar Energy, used "dodgy sales tactics" and "hugely overstated" the potential benefits of installing a solar thermal system.
.
.
Everest said: "We are disappointed that our representative failed to use the sales support documentation provided and made claims he knew to be false.

It would never have happened in Ted Moult's day.....

 

[crappy]

if I can add my 10p worth...

PV, in its "normal" form is a waste. I fully agree with that. However, there is a much better way to use it.

Having it generate all your electricity while you are not home to use it is pointless. If you store said electricity...

My current system, 1.2KW, recharges batteries by day and my house uses them by night. With the current weather I can recharge my 270AH battery in the morning / early afternoon (charger consuming about 400W, all supplied by the PV array)
Currently only the lights run off the battery and a 500W sine-wave inverter. When I get the 2KW one back I'll be extending it.

All of this is also using a grid-tie invertor so I am getting the FIT, supplying power for the fridge etc and still have excess.
Only a clear, sunny day I get a peak of 1.2KW from the array, on a dull rainy day I get about 400-600W. I am expecting to run slightly short in winter but still managing to supply most of my energy from the PV / battery setup.


I did not pay the [exorbitant] rates the MCS installers charge (sorry fellas - daylight f'ing robbery) but rather the slightly overprices MCS approved panels and gear and paid for it to be commissioned. Happy days. Savings on getting it done - about 5k.
With my current monthly bill at £220, if this reduces that (and it already is) then it should take me about 2.5 years to recoup based on savings alone. With the FIT, even less (in 8 weeks I am due a cheque for £86 for FIT).

(I know there are other running costs involved but for the sake of simplicity...)


PVs biggest downfall is you're not at home to use it when it is being generated. Basically a waste...