# Solar PV advice sought



## misterfish (13 Mar 2009)

We're trying to do what we can to go green in a sensible way. All the light bulbs are low energy cfl where possible, cavity wall is insulated, loft has almost 300mm insulation, central heating has gas condensing boiler with heating zones with programmable thermostats as well as all radiators having thermostatic valves, we have a large well insulated mains pressure hot water tank with a solar array on the roof. Our electricity supplier is a 'green' hydroelectric company.

So we were wondering about solar PV. We've tried looking around and found that any grants available are small compared to most of the rest of the EU and North America and are really questioning the cost effectiveness of these systems. If we were to spend about £15,000 on a mains connected system (where we sell back excess generation to the 'grid') would we be taking a sensible step? Apart from the 'feel good' factor and the possibility of being less reliant on external supply would we do better to save the money (with currrent derisory rates of interest) or 'invest' it in a PV system. We've got a south-west facing roof and are on the south coast in sunny Chichester, West Sussex.

Any comments or suggestions would be appreciated.

Misterfish


----------



## MikeG. (13 Mar 2009)

Hmmmmmmmm.....

I have been studying these things for 20 years, and take a professional interest, as well as a personal one, in all things "green". I am a huge advocate of super-insualtion, of mechanical ventilation systems with heat recovery, of low-embodied energy construction techniques, of wind turbines, and solar hot water systems etcetc.........but, I have very little time for photovoltaics.

I'm afraid that in our cloudy climate the enormous amount of energy that goes into their production can take up to 12 years to be re-paid in terms of output from the cells. Given that they have a reducing output over their life, and are generally thought of as having a working life of 20 to 25 years, you can see that they are currently extremely innefficient in energy terms in this country.

If you live on the continent, or in Canada, or Africa, Australia, the Middle East, etc.......then the numbers are entirely different.

The economics don't work either, hence the large subsidies.

My advice would be to invest in super-insulation, triple glazing, solar hot-water systems, draught proofing, mechanical ventilation systems etc, before you even consider photovoltaics.

Mike


----------



## Jake (13 Mar 2009)

Mike, you would know, if anyone - have you ever seen any data on the efficacy of IGU seals at retaining inert gas fills? I see loads of sceptical comments around about how fast the gas "must" dissipate, but never any proof.


----------



## MikeG. (13 Mar 2009)

I haven't seen any data, Jake..........but my experience is that different manufacturers seem to manage to get entirely different performance levels from the same construction and components.

Swedish window manufacturers, and Germans, seem able to make double and triple glazed units that last "forever", whereas many others, inc. a number of UK companies, using exactly the same spec, seem to have a high failure rate at 7 to 10 years. I have no figures to back this up, though, sorry.

Mike


----------



## Jake (13 Mar 2009)

I assume by failure, you mean (easily observeable) condensation?

If so, no need for much data! 

It's those pesky invisible gases which can't be distinguished by eye.


----------



## MikeG. (13 Mar 2009)

Any failure of the gasket leading to the loss of the inert gases also leads, inevitably, to the intake of air. Now, whilst there is sometimes a dessicant within the units, this can only last for so long in relation to the quantities of moisture in air, and so _any_ leakage of gas will soon lead to condensation.

So, the simple answer is.....yes!

Mike


----------



## Jake (13 Mar 2009)

Hmm, not sure you would necessarily see condensation in the absence of a pretty major seal failure, rather than just a bit of gas-permeability in the seal (after all the performance of an IGU with say a krypton fill will plummet if you lose 50% of the fill, and the dessicant ought to be able to deal with the moisture in the 50% of gap-volume of air that replaces it).

However, I have found an answer of sorts, as it seems there is now a (shortly to be compulsory) European standard, e.g:

_ Intercept Warm Edge Spacer Achieves BS EN1279 Part 3

Intercept Spacer Systems have now passed BS EN1279 Part 3, the section of the standard that deals with insulating gas leakage. 

The leakage rate called for in the Standard is set at 1% per year. The GED manufactured Intercept units achieved remarkable results at better than half the requirement._


----------



## tnimble (13 Mar 2009)

I would certainly not consider going the photovoltaic route except for as just to experiment if you have really deep interests in that (and deep pockets)

The only effective means of generating electricity from solar engergy is going the CSP route. This means to collect, focus, heat capture, convert heat into electricity. There are two paths to do this. Use hollow mirrors to collect and focus the light on a glass tube filled with water / steam that is super heated. The super heated steam drives a turbine. The other way is to use Fresnel lens capped cells. The first takes up lots and lots of space and can only be done on very large scale. The second method is scalable but still expensive and hard to obtain in small quantities.

The large two drawbacks with photovoltaic panels already mentioned like:
- costs more than they will provide over their life cycle
- production and recycling costs of the panels uses many resources whch contributes largely to the above

To this can be added:
- if for climate change, using solar energy contributes to warming the planet. All the effectively produced energy warms the planet at the point of consumption (the heat given off the a bulb, a telly, the fridge etcetera). The system itself is not 100% efficient (far from it) only a small amount of the losses of the 'system' are reflected light the rest is heat production. Most surfaces of the earth have high solar energy reflective properties in comparison. *

*) The human contribution to climate change is debatable to say the least and tiny in comparison to the contribution of natural processes like volcanic activity, rotting vegetation, solar activity, variations in the density or space, distribution of rain fall.


----------



## wizer (13 Mar 2009)

I asked about this before and got the same answer. Which is a shame because I really like the idea of free electric, as opposed to free warmth. i.e I use a lot of electric.

So what about other methods of cheap or free electric? Wind?


----------



## big soft moose (13 Mar 2009)

wizer":27416ygo said:


> I asked about this before and got the same answer. Which is a shame because I really like the idea of free electric, as opposed to free warmth. i.e I use a lot of electric.
> 
> So what about other methods of cheap or free electric? Wind?



at the moment - unless you have a very fortuitous location (like my mate ben who bought an old watermill in ireland and installed a turbine to run off the wheel) there is nothing that really works for "free" power (except illegally wiring in to a streetlamp  - and i would not advocate that route) or more acurately there are workable solutions but the capital cost is such that repayment will take many years.

of course that is a todays energy costs - if the unit price went up dramatically as fossil fuels run short then the renewable option would look much more affordable.


----------



## wizer (13 Mar 2009)

big soft moose":ai073qrk said:


> (except illegally wiring in to a streetlamp  - and i would not advocate that route)



Wistfully looks out the window at the street lamp that keeps him up at night...

Actually I have seen this happen on a couple of occasions. Trying to remember the first, but the last time I saw it was on my old allotments. The guy was digging one day and found the cable from the perimeter lamp. Some how he managed to spur off it into his shed. Got caught when he was using an electric strimmer one day :lol: :lol:


----------



## MikeG. (13 Mar 2009)

tnimble":3bkpuybb said:


> The human contribution to climate change is debatable to say the least and tiny in comparison to the contribution of natural processes like vulcanic activity, rotting vegetation, solar activity, variations in the density or space, distribution of rain fall.



This is a blatant attempt to stir up controversy. Out of the woodwork will come all sorts of strange comments, now. This idiotic argument should be turned on its head by asking...........how is it that we can have altered the chemistry of the atmosphere so much, and, as it now turns out, the oceans as well, without it having any effect?

Don't hijack threads.

Here is a chap wanting advice on PV's..........please start a new thread in Off Topics with a clear title if you want to start this nonsense all over again. I wont be contributing.

Sorry for being so hot under the collar about this, but this is half a lifetime's work for me, and I can't even begin to understand the mentality of flat-earthers who disregard all of the science.

Mike


----------



## TrimTheKing (13 Mar 2009)

Jake":3edicsg7 said:


> and the dessicant ought to be able to deal with the moisture in the 50% of gap-volume of air that replaces it).


Just a thought but, what about when the dessicant is 'full'?

My wife is the CFO of the worlds biggest manufacturer of silicates, and I was talking with their OPS director down the pub one day asking if he could get me a few bags for use around the workshop. His comment was that it isn't the right thing to use because it is just like a sponge, when it's full it stops soaking up any more water until it has dried out.

Slight deflection from the topic (and not relevant to windows) but his advice was a dehumidifier, which I now have, and a hygrometer which tells me the RH in the workshop and outside.

To caveat this, I am speaking from what I was told, not with any level of authority based on my own understanding.

Cheers

Mark


----------



## TrimTheKing (13 Mar 2009)

tnimble":d88lomwr said:


> vulcanic activity


What has Mr Spock got to do with any of this? 

Sorry, had to.

Cheers

Mark


----------



## Jake (13 Mar 2009)

TrimTheKing":24gw9sks said:


> Jake":24gw9sks said:
> 
> 
> > and the dessicant ought to be able to deal with the moisture in the 50% of gap-volume of air that replaces it).
> ...



Well, at that point the window starts to fail ... but by that point the original fill gas really must be long gone unless the dessicant is extremely ineffective, surely?

edit: anyway this is all well OT, so apologies to the OP for the diversion.


----------



## tnimble (13 Mar 2009)

wizer":3kwd65bz said:


> So what about other methods of cheap or free electric? Wind?



Wind is one (although the effectiveness increases when the wind is captured at greater height (about 160 meters and higher) and at lower blade rotational speed, for this the blades needs to have the blades aligned not only with the wind direction but also the pitch of the blade with the wind speed.) For home usage a small horizontal wind turbine can be used, but vertical wind turbines can be used in more residential areas.

Water energy from flowing water like rivers has great potential for small scale usage. Utilisation on larger scale often has too much impact on the surrounding environment and water transportation.

Is you would happen to life in a very active area (Geysers, hot gas vents and those kinds of phenomena) one could use this to drive a steam powered generator. Since these areas are not quite residential most of these projects are large scale. Experiments are done to gather energy more directly from the earth its core.

Also a generator could be run on swamp or bog gasses. This has much potential in some areas to be utilised on small scale on a per house basis.

Other methods like full cells have large disadvantages like the PV panels.



Mike Garnham":3kwd65bz said:


> This is a blatant attempt to stir up controversy. Don't hijack threads.


Sorry it wasn't meant like that, it was only a footnote (hence the asterisk).



> This idiotic argument should be turned on its head by asking...........how is it that we can have altered the chemistry of the atmosphere so much, and, as it now turns out, the oceans as well, without it having any effect?


Please don't put words in my mouth/fingers. We do mayor harm to and exploit our environment and Earth its inhabitants in a gazillion ways. The comment is only and only applicable to climate change as in global temperatures.

And I would request indeed not to go into any discussion about CC.


----------



## dickm (13 Mar 2009)

Aberdeen Univ is running a series of seminars on "Energy Controversies" at the moment. Last night's was on Alternative energy sources, and one suggestion, among a lot of others, was that solar PV, particularly using large array of solar tiles, was "becoming economic". I used to work with the guy who made this prediction, and he is a bit of an optimist, but does have his finger on the pulse in this area. So possibly worth looking out again soon.

According to the panel on this occasion, tidal, wave and wind are the most likely big sources in the near-ish future, but only if Govt can be prepared to back the start-up costs rather than pouring money into *ankers' pockets.
Not that most of us can use tidal or wave! 

Solar thermal (whatever recent reports have said) does seem to be economic now, especially if combined with heat storage (i.e. basically, a d*** great hot water tank). We are probably going down this route shortly, so will report back next year.


----------



## dickm (9 Oct 2010)

Just thought I'd update this thread, as there doesn't seem to be anything more recent on PV around the forum. 
Having looked at the sums regarding the Feed In Tariff, they seem too good to be true, so I've broken the rules of a lifetime, and become an early adopter of new technology. We've just had 3.9kW nominal output PV panels installed on the roof, and in two nice sunny days, had pretty reasonable generation. The shine (literally!) rather taken off on the last couple of days when Aberdeenshire went dreich, with a cloud base just above the trees, so generation has been pretty negligible.
But talking today at a meeting to one of the other (2? 3?) folk who have PV installed round here, it looks as if even with our weather the investment will be better than most other opportunities. Our kids should recoup the investment anyway when they pop us into boxes and sell the house.


----------



## misterfish (10 Oct 2010)

As the OP (from over 18 months ago) I'll also add our update.

When we saw the Feed in Tariff rates for PV we also thought it might be worth pursuing, so we started investigating the feasibility/options back in March. This is not a DIY option but has to be installed by approved contractors using approved equipment so it isn't a cheap 'on a whim' purchase.

Anyway, we finally ended up with a 3.25KW notional power system that was installed in August. The actual maximum output of mains power we get is 90% at just over 2.8KW - so far we have generated just over 500kW. 

The system has rendered the old Electrisave (OWL) energy monitor useless during the day as there is no way to tell if the total displayed is usage or export.

If anybody is interested in more details then let me know - (I have also been recording daily power production (my scientific/geeky nature).

Misterfish


----------



## RogerS (10 Oct 2010)

What's the revenue return so far, misterfish?


----------



## Eric The Viking (10 Oct 2010)

misterfish":2n6dnw2r said:


> As the OP (from over 18 months ago) I'll also add our update.
> 
> When we saw the Feed in Tariff rates for PV we also thought it might be worth pursuing, so we started investigating the feasibility/options back in March. This is not a DIY option but has to be installed by approved contractors using approved equipment so it isn't a cheap 'on a whim' purchase.
> 
> Anyway, we finally ended up with a 3.25KW notional power system that was installed in August. The actual maximum output of mains power we get is 90% at just over 2.8KW - so far we have generated just over 500kW.



Do you mean 500kWh (kilowatt-hours)? (kilowatts are a rate of energy production or use, not a quantity). 

Assuming kWh, and that 45 days have elapsed since installation (mid- August to mid- September plus two weeks and a bit), that gives an average power output of less than 0.5kW. Assuming you can only generate effectively for 8hours/day, it rises to roughly 1.5kW when it's working. I think the figure you're measuring is the peak output. 

I've got a few questions: 

1. Do you have a large battery array and an inverter, so that you can store what you produce?

2. Do you 'sell' to the grid, if so at what rate? Are you required to remit the 5%VAT to the government?

3. How much did the installation cost, and was there any sort of guarantee on output and longevity? 

I have 8sqm of water heating panels on our roof. It's usable even in the depths of winter (when the sun is shining), but I can't store sufficient hot water to take full advantage of it. 

Was it cost effective for us? That's hard to answer because the energy produced is very hard to measure. It cost around £4,000 to install, but some elements of the system were already in place (boiler and tank in proximity to the roof). We also scheduled the work to coincide with scaffolding being up, so that cost was spread. Our gas bills are very small in the summer (about a fivefold difference from winter quarter's usage), but it's not quite enough at present to cover the morning household dash to the showers. It is, however, long-lived, very simple in technology terms, and very low maintenance. I intend to 'upgrade' it with an additional water tank when I can, part of the delay is cost, part because I can't work out a suitable plumbing arrangement at the moment.


----------



## RogerS (10 Oct 2010)

There's the rub. All these 'high-tech' (as compared to a load of oft insulation) options have a really poor cost-benefit-analysis with payback times in eons.

I'm with Mike Garnham on this...anyone for a PassivHaus?


----------



## misterfish (10 Oct 2010)

Right - yes I do mean kWh, so we have generated over half a megawatt.

We did look into the possibility of having a large battery array, but the cost and maintainance of the batteries was somewhat prohibitative and suitable control/switching equipment was not readily available. The recommendation was that if we suffer lots of power cuts that the most cost effective solution was to obtain a diesel generator - but our mains supply is OK.

The way it works is that when generating power we use what what we produce and any excess is exported to the grid. If not generating enough we top up from the grid.

As it is solar PV it only generates when light falls on the panels - basically the brighter the sun the more power produced.

As for payments. The Feed in Tariff for PV is 41.3p per kWh generated, irrespective of whether we use or export the power. On top of this is a payment of (about) 3p per kWh per unit exported to the grid. Currently the electricity board meter cannot register exported power (which will change when smartmeters are installed 'in the next few years'. Until this time it is 'assumed' that half of what we generate is exported.

So we actually receive 42.8p per unit generated. This rate is index linked to inflation and guaranteed for 25 years (if you believe government promises). Also any payments made are not liable for income tax. So in the last two months we have earned £220 tax free. We remit nothing to the government.

The other thing is that our consumption of power from the grid will reduce and consequently so will our electricity bill.

I'll put together a graph showing our daily production a bit later.

Misterfish


----------



## misterfish (10 Oct 2010)

I've kept a spreadsheet of daily production since the system was installed and these are the monthly graphs.







Also, (due to my analytical/geeky nature) I've now 

I've had a datalogger attached to the system for nearly three weeks - this allows recording of production values every 5 minutes!

Misterfish


----------



## dickm (10 Oct 2010)

Interesting, Misterfish. Don't think we will get quite as much up here in the short days, but in summer, when it hardly get's dark, we might catch up! So far, we've only managed 29kWhr over 5 days, but it's been real dreich most of that time. Unfortunately, our roof is only 30 degrees, not the 60 that is recommended for our latitude, so we can never hope to generate the rated 3.9kW, but I'm happy so far.

At the moment, I can't see another investment that is likely to make the same return (it's PROBABLY also the most "green", but s*d that if the economics make sense :twisted: )


----------



## Eric The Viking (10 Oct 2010)

misterfish":79j2wu6o said:


> Right - yes I do mean kWh, so we have generated over half a megawatt*-hour*...
> 
> ... We did look into the possibility of having a large battery array, but the cost and maintainance of the batteries was somewhat prohibitative and suitable control/switching equipment was not readily available. The recommendation was that if we suffer lots of power cuts that the most cost effective solution was to obtain a diesel generator - but our mains supply is OK.



It's not for power-cuts specifically, but for night time. You must already have the locked inverter (solar cells are DC output), so a battery farm ought to be straightforward. Although that might cause you to fall foul of all the HSE regulations for battery rooms - tiled walls, special drainage, ventilation, etc. Lead acid is very low maintenance, as long as it's the right sort (will stand deep discharge etc.). The wet alkaline ones are even better, but nastier chemistry.



> As for payments. The Feed in Tariff for PV is 41.3p per kWh generated, irrespective of whether we use or export the power. On top of this is a payment of (about) 3p per kWh per unit exported to the grid.



Flippin' 'eck! At that rate I ought to be billing SWEB for the solar panel I've got to trickle-charge the bike battery! Seriously, that means there is no incentive to store (or use) any of the energy you produce at all, since it's much more valuable to you sold-on to the grid.

Disconnect the house from the solar system and sell all of it!



> Currently the electricity board meter cannot register exported power (which will change when smartmeters are installed 'in the next few years'. Until this time it is 'assumed' that half of what we generate is exported.



I thought you could wire them up to run backwards!  At least, that's the way it's done on some of the estates round 'ere. Why don't they simply put one meter on your array's output and compare that with the standard one on the incoming supply? The difference is what you use over what you generate, or vice-versa, depending on whichever is the bigger number.

But as I said, it doesn't make economic sense to actually use any of it yourself!



> I'll put together a graph showing our daily production a bit later.



Seriously (again), that will be very interesting. 

I have to say though that it sounds complete nonsense in absolute economic terms - what were they thinking when they set the scheme up??? That rate is getting on for 5x the normal rate per consumer unit (must check my bill), which is hardly efficient (from everybody else's perspective!).

You also didn't say how much it cost to put in - a ballpark figure would be interesting. One idea that strikes me is that, since nobody's getting any decent return from deposits and shares at the moment, this might actually be a worthwhile investment in real terms, provided you really can sell the output to the grid for the foreseeable future


----------



## Eric The Viking (10 Oct 2010)

misterfish":1scug46n said:


> I've kept a spreadsheet of daily production since the system was installed and these are the monthly graphs.
> 
> 
> 
> ...



I think my earlier post 'crossed' with yours. It certainly shows how gloomy September was! Out of idle curiosity, at what angle are they to the horizontal, roughly? I only ask because October seems surprisingly good so far (on the sunniest days). I'm assuming that's because the array is more perpendicular to the sunlight at the moment.


----------



## misterfish (11 Oct 2010)

The idea of the batteries to provide 'dark hours' power was included in our original wish list, but at this early adopter stage (at least as far as the UK is concerned) suitable and approved equipment is not available (unfortunately).

Now as far as the payment is concerned, the 41.3p per kWh is not a payment for the actual electricity but is a payment for green generation for the whole of the UK - it's to do with the legally binding EU/international undertakings given by the government to reduce carbon emmisions by at least 20% by 2020. Apparently if the UK doesn't attain its targets there are huge financial penalties that the country will have to pay. Hence this feed in tariff (FIT) payment is to encourage people to do their bit towards the target.

The actual electricity we produce is ours to do with as we wish. It is an option (renewable annually) to sell the excess back to the grid via the FIT scheme. Our electricity board supply meter is a digital device and unable to run backwards, but some of the older meters (those with the rotating disk) I believe can run backwards. Attached to our system is an approved 'total generation meter' that is used to calculate our payment.

We spent about 19K on our system of 15 panels and extra monitoring equipment. The panels are guaranteed for a long period (something like 20 years) and the inverter for 5 years.

The rear of our property faces SSW and part of the whole process was a critical analysis of shading to ensure the panels receive at least 6 hours per day of sun (cloud permitting). Part of the installation and certification of the system is an expected average annual output which in our case is 2580kWh

Our 15 panels (each rated at 215 watts) are split into 3 strings of 5 panels with 5 on the main roof (at about 43 degrees) and 2 lots of 5 on the flat roof of the granny annex/sun room. Those on the flat roof are at a much shallower angle. The software/hardware equipment used during the site evaluation allows tweaking of angles to give the best output. As the angles of our panels vary it will give a more equal output throughout the year. This shows what it looks like.






One of our early concerns was the requirement or not for planning permission as the rules had been changed to include solar panels in permitted development. Our property is considered to be in a 'strategic gap', is within the Chichecter Harbour area of outstanding beauty but outside of the Chichester Harbour conservation area. We took photos of what we were looking to do and spent an hour at the council offices with the duty planning officer. If we had been in the conservation area we would have needed planning permission. If the panels protruded more than 200mm above the ridge of the house or overhung the back of the property by more than 200mm the planning permission would be required. It was reassuring to see that the council offices in Chichester had their own PV system with a large internal production display and to then be told that they encouraged such systems.

I'll read back over the thread and see what other questions I've missed and answer them a bit later.

Misterfish


----------



## samharber (11 Oct 2010)

tnimble":3esajk75 said:


> *) The human contribution to climate change is debatable to say the least and tiny in comparison to the contribution of natural processes like volcanic activity, rotting vegetation, solar activity, variations in the density or space, distribution of rain fall.



Without wanting to go off at a major tangent, this is palpably false. 
There is no debate* as to whether or not humans are contributing to climate change. We are. The main debates are what the feedback mechanisms are and how the CO2 parts per million can be reduced to a (comparatively) safe level.
Both the US Geological Survey and the Royal Geological Society have recently shown that annual human CO2 output is massively greater than the average annual volcanic emmissions (that also have global cooling effects). Also, rotting vegetation, solar activity etc are all part of the background state and would take place at pretty much the same rate regardless.

I now return you to your scheduled programming.

*There's no debate amongst climate scientists, but a lot of poor quality argument from non scientists.


----------



## wobblycogs (11 Oct 2010)

Very interesting Misterfish, thanks for telling us about your system. I've kept an eye on the technology for years now but not the economics of it. It sounds like if you have a south'ish facing roof it's viable to have PV generally.

One thing I was wondering though, how come you didn't have all the panels installed on your roof. The majority seem to be on the flat roof which surely don't generate as much. Are they panels very heavy?


----------



## dickm (11 Oct 2010)

Eric The Viking":2lb29wox said:


> > As for payments. The Feed in Tariff for PV is 41.3p per kWh generated, irrespective of whether we use or export the power. On top of this is a payment of (about) 3p per kWh per unit exported to the grid.
> 
> 
> 
> ...



Like I said in my earlier post, financially it's too good to be true! But it seems it is true.
And the FIT is guaranteed not to reduce for 25 years. Hence (although I do have a greenish conscience) our decision that it made complete sense to invest. Our system is rated at 3.9kW, and cost about £14k. It's made up of 17 panels, each about 1.5 by 1m, on a roof that faces due south. Unfortunately, not quite steep enough pitch, but setting the panels more vertical would have cost a lot, and might not be a good idea given the windspeeds round here (now, could I fit a turbine mast in the corner of the garden??). Planning is not a problem, because recent legislation makes renewable generation systems a permitted development in almost all areas. You do still have to work within Building Regs, and it probably makes sense to get a structural survey to be absolutely sure your roof is strong enough (don't get the charlatan who did our survey - but that's another story).

With regard to the "green" aspects, an old academic friend tried to convince me that the carbon cost of manufacturing the panels outweighed the likely lifetime savings, but the latest figures I've seen indicate that the "carbon payback" is about the same as the economic one, around 7 years under good conditions.


----------



## misterfish (11 Oct 2010)

The panels we have are Sanyo HIP-215NKHE1 - they are 798 x 1580mm and each weigh 15kg. http://www.coolpower.ie/products/datash ... Series.pdf The mains connected inverter is a Fronius IG30 which allows the input from the three strings of panels. http://www.fronius.com/cps/rde/xchg/SID ... G_HTML.htm . The panels on the flat roof are fixed with an aluminium framework system that is lightweight and strong with most of the parts made by Schuco. 

Ideally we would have liked more on the two parts of the main roof but the hipped part of the building that protrudes southwards produces shadows early in the day as does the step between the two parts of the roof and after discussion with the installation company we went with what seemed like the best compromise.

Our installation company were extremely thorough with the survey. The initial phone call to them taking well over 20 minutes looking at Google Earth to check the siting and aspect. The the initial site visit to evaluate shading and potential generation. Then the structure checked by a professional roofer before and after installtion with then doing the necessary work to ensure the watertightness of the flat roof. In fact the whole process was extremely thorough and professional and we would highly recommend Southern Solar.

As Dickm states the payments are guaranteed for 25 years and will rise in line with inflation.

The actual angle of the panels is always a compromise - in summer when the sun is at its highest (and strongest) the panels do best at a low angle, but in winter it's the other way round.

Misterfish


----------



## jeffinfrance (11 Oct 2010)

generating electricity is not difficult.

storing electricity is.

the national/global energy providers do not store electricity. electricity is only generated when it is required. if you are generating more electricity than you are using and sell it back to the "grid", where does it go?

oh by the way, anthropogenic global warming does not exist. enjoy your cold winter!

jeff


----------



## Eric The Viking (11 Oct 2010)

misterfish":3jas20kb said:


> In fact the whole process was extremely thorough and professional and we would highly recommend Southern Solar.



As would I! 

They did our hot water installation very proficiently (see this video for my daughters' overview). I was especially impressed by the tuning of flow rates and setting up the hysteresis control on the system.

I remain unconvinced by the overall value of PV though.

Cheers,

E.


----------



## wobblycogs (11 Oct 2010)

There will probably never come a time when we generate more electricity that we need. Any surplus energy generated gets pumped into the grid as you say and used by others. 

There are some industries, like aluminium smelting, which use such vast quantities of electricity they have agreements with the grid to draw power only at off peak times, this helps balance the load on the grid throughout the day which helps the power generation companies as it means they need fewer fast on/off (read expensive) generation sources like gas fired power stations to meet peak loads. This means they can have more cheap coal fired (base line) generation.

If the whole country suddenly went PV generation loads of extra power would get put into the grid when the sun shone and it would be used by industry or perhaps even exported to parts of Europe where the sun wasn't shining.

Worst case we could store some of the power. A common large scale energy storage method is called pumped storage where they pump vast quantities of water up to a high level reservoir. Pumped storage like this is a great way to meet sudden spikes in load as it takes only a few minutes to come on-line.


----------



## cambournepete (11 Oct 2010)

my brother has just had PV installed on his house in sunny Suffolk.
As he worked for Eastern Electricity all his life and is careful with his cash* it must be worth doing if you plan to stay in your house for a long time.
He's getting a new meter installed as his started running backwards...

*That makes him sound mean - he definitely isn't


----------



## misterfish (11 Oct 2010)

I remember seing one of those 'How do they do it' type programs recently on Discovery where they were showing how they keep the electricity supply balanced. They have a steady background supply with other power staions on standby for rapid action when needed (like everybody making a cuppa after Corrie. They included the pumped option to refill reservoirs when excess power was available. It seemed to be a constant tuning to keep the voltage and 50Hz balanced with demand as well as coping with network problems.

Misterfish


----------



## Eric The Viking (11 Oct 2010)

misterfish":2uipxwc2 said:


> I remember seing one of those 'How do they do it' type programs recently on Discovery where they were showing how they keep the electricity supply balanced. They have a steady background supply with other power staions on standby for rapid action when needed (like everybody making a cuppa after Corrie. They included the pumped option to refill reservoirs when excess power was available. It seemed to be a constant tuning to keep the voltage and 50Hz balanced with demand as well as coping with network problems.
> 
> Misterfish



That's why Dinorwig, and, I think, Ffestiniog and Cruachan*, are owned by the National Grid Company rather than one of the generators - they are giant 'batteries' rather than generating stations.

Even if we did have more nuclear, there would still be difficulties because the rapid changes in demand are too fast for nuclear stations to easily cope with. I'm not sure how Switzerland does it (IIRC they're almost entirely nuclear), but the risks of not managing the supply-demand relationship properly are either over/under voltage (which blows things up) or a shift in frequency (which also blows things up, and sets the clocks wrong).

Incidentally, does anyone know where the smallest, but arguably most dangerous British reactor was sited? It's not there any more, but I once walked past the window, none the wiser...

Cheers,

E.

*possibly Scottish Hydro.


----------



## RogerS (11 Oct 2010)

Eric The Viking":1991zpye said:


> .....
> Incidentally, does anyone know where the smallest, but arguably most dangerous British reactor was sited? It's not there any more, but I once walked past the window, none the wiser...
> 
> Cheers,
> ...



Sellafield?


----------



## wobblycogs (11 Oct 2010)

AIUI nuclear is somewhere between coal and hydro-electric / gas in terms of how long it takes to go from cold to full power (closer to gas though). I would imagine the Switzerland (and to some extent France) cope because they are wired into a single grid that spans most of mainland Europe. It's unlikely that everywhere in Europe will all have a peak demand at exactly the same time so some power trading would sort out any problems. 

I would have said probably the most dangerous nuclear plant in the UK is Dounreay as it is getting old and was designed for nuclear experimentation at a time when we didn't fully understand the risks. Decommissioning it is certainly going to be a real challenge. It's a close call between that and Windscale though. You've got to admit that setting fire to a reactor is the mother and father of all bad days at work


----------



## Eric The Viking (12 Oct 2010)

RogerS":21tkcy8p said:


> Eric The Viking":21tkcy8p said:
> 
> 
> > .....
> ...



Nope. 

Much closer to the seat of gummermint.


----------



## Yetty (12 Oct 2010)

Queen Mary College London, Department of Nuclear Engineering ?


----------



## Eric The Viking (12 Oct 2010)

wobblycogs":2i8tb3rv said:


> It's unlikely that everywhere in Europe will all have a peak demand at exactly the same time so some power trading would sort out any problems.



Peak demand often occurs at _exactly_ the same moment over large parts of the planet, because of the televising of international sporting events. The classic examples are the Superbowl and the World Cup final. The moment the whistle goes for half time, several tens of millions of kettles go on.

The joke in the BBC about Dinorwig was that it was built to counteract the commercial breaks in Corrie. Back in the late 1970s I remember seeing the demand graphs that showed this. This type of synchronised demand is what pumped storage excels at covering. IIRC, Dinorwig can come on stream within seven seconds if the turbines are already spinning, and 16 seconds to full output (1800MW), although I think it's only got less than an hour at full output**.



> I would have said probably the most dangerous nuclear plant in the UK is Dounreay as it is getting old and was designed for nuclear experimentation at a time when we didn't fully understand the risks. Decommissioning it is certainly going to be a real challenge. It's a close call between that and Windscale though.



I think it's already in hand. One thing is that the plant's capacity is considerably smaller than later 'production' reactors. As I hinted earlier, we've already decommissioned and fully cleaned-up after what was probably the riskiest one of all. It can be done.



> You've got to admit that setting fire to a reactor is the mother and father of all bad days at work



When the CEGB HQ was in Bristol in the 1980s, one of my friends worked as a metallurgist on the 'local' nuclear stations (apparently radioactive particles do funny things to the physical properties of metals over time). He was a great fan of our AGR (Advanced Gas-cooled Reactor) design, on the basis that the half-life of the radioactive products from the CO2 primary coolant is very short (tens of days). Thus, in the event of a catastrophic primary containment leak, one stratagem is simply to leave the secondary containment sealed and come back in a few months. This is in contrast to the US PWR designs, now prevalent, that are not 'inherently safe*' in the same way. Or so I was told...

I was also told that Magnox had similar safety advantages, but I believe both it and AGR development were dropped because of their higher costs compared to PWR and derivatives. There is presently talk of a new class of Thorium fuel-cycle reactor, which might be both cheaper on fuel and safer.

If you're interested, http://www.angelfire.com/extreme4/kiddofspeed/chapter1.html has a lot of pictures of present-day Chernobyl.

Cheers,

E.

*for rather odd values of 'safe', admittedly!

**I checked Wikipedia before writing this. I think it's article is a little disingenuous in that the 6 hours it claims probably isn't at full output. I'm fairly certain I was quoted a 30 mins full load run time and 7sec warm start by an engineer on a visit in the early 1990s, but I may be wrong. My memory plays tricks on me at the moment.


----------



## Eric The Viking (12 Oct 2010)

Yetty":3ioe9k7g said:


> Queen Mary College London, Department of Nuclear Engineering ?



Theirs isn't/wasn't in the capital, IIRC. But I stand to be corrected (often am).


----------



## RogerS (12 Oct 2010)

Slight OT. but relevant to green energy.....I have two books for sale as a pair:

Choosing Windpower £7.99

Ground Source Heat Pumps £19.99

Yours for £17 including postage


----------



## Eric The Viking (13 Oct 2010)

The reactor I was thinking of was "Jason". It was constructed in one of the original buildings of the Royal Naval College, Greenwich. It was very small, used for training submarine engineering personnel. The spec. listed the output at around 3kW, "about enough to boil a kettle." [edit] Wikipedia gives the output at 10kW, but I've heard 3kW quoted as typical - that may have been generative capacity rather than heat though).

It was decommissioned in 1999: http://en.wikipedia.org/wiki/JASON_reactor

Apparently, it caused us to be sued by the European Union!


----------



## miles_hot (13 Oct 2010)

Misterfish

Many thanks for sharing all the data etc - very interesting. One thing that confuses me a little is that you said that it cost 19K to put in and you "made" 220 in the last two months. This suggests a payback period of around 14 - 15 years which whilst better than the 20-25 years it was when we looked at it 5 years ago still isn't a great return on investment.

Have I got something wrong here?

Miles


----------



## misterfish (13 Oct 2010)

We're not actually doing it purely for financial reasons - we have a fairly green ethos, though the return on expenditure is still an important factor.

We did a fair bit of investigation before going ahead and found the 'Solar Electricity Handbook' by Michael Boxwell a useful and informative guide. It contains some useful tables of 'insolation' levels on a month by month basis taken from data collated over a 22 year period upto 2005 - data was collected every three hours for 24 hours a day and then 'crunched' to give an average of solar radiation in kWh per square meter for each month of the year. 

These are the figures for Portsmouth and Aberdeen so you can see the potential differences between the two locations of me and dickm, bearing in mind that Portsmouth is at latitude 51 north and Aberdeen is 57 north







Although not a definitive amount of 'energy' this does give a (hopefully realistic) comparitive value of what we may expect from month to month allowing for the vagaries of the British weather. I'll have a play with Excel to get some 'what if' type totals based on our experience so far and then add the results.

As one of the early adopters of PV we have to accept that we are guinea pigs and taking a risk. We wouldn't have taken the plunge if we weren't comfortable with the finances. SWMBO and I were brought up to be financially aware/responsible and we both have company pensions as well as AVC pensions we also purchased as well as the State pensions we have both contributed to throughout our working lives (in my case I don't actually get my State Pension until I turn 65 in a few years time.

Misterfish


----------



## SEOaaron (3 Jan 2011)

Swindon receives more insolation that Aberdeenshire, as shown in the graph above. Also, 5 years ago, there was no government backing, such as the Feed-In Tariff.

A modest system that might cost in the region of £11,000 (retro fitted) should in theory allow you to gain a ROI of up to 9% depending on your roof tilt and orientation, resulting in a paybakc period of just over 10 years. 

The optimum tilt is around the 30 degrees mark, and the orientation is obviously Due South!


----------



## misterfish (3 Jan 2011)

Yes, quite true for Swindon which shows a record of

Jan Feb Mar Apr May Jun	Jul Aug Sep Oct Nov Dec
0.75	1.37	2.31	3.57	4.59	4.86	4.82	4.2	2.81	1.69	0.92	0.6

Reports from others indicate that there are a number of 'less knowlegeable' installers around who lack either the skill, analytical equipment or experience necessary to accurately analyse any potential PV siting location and who are just interested in a quick buck.

Any installation should be a considered decision and not a spur of the moment whim.

So far, our system is producing a bit more than expected and predicted by the NASA historic records - despite the miserable weather. 

Misterfish


----------

