PHOTOVOLTAIC CELLS

We are just about ready to start thinking about setting up a PV system. The main difficulty so far has to do with us understanding just what it is that the various Chinese suppliers have on offer. Our thinking is that we need to start by costing the various kits, all before we start thinking about our specific needs.

And just in case you dont know..... Photovoltaic or PV cells are systems that convert sunlight directly into DC electricity. Solar PV, s can be used at a domestic level for lighting, and for powering low voltage appliances like radio, TV, computer, small water pumps. A small PV system will only produce a few hundred watts of electricity at most, but when linked up with a battery, and when used efficiently, they will provide enough electricity for a small cottage. Photovoltaic systems – sometimes known as PC’s – work by converting sunlight into to DC or direct current electricity. A typical PV cell structure – made up in sandwiched layers – has a back contact, two silicon layers, an anti-reflecting coating, a contact grid, and an encapsulating surface. When the rays of the sun – in the form of photons – shower the structure, the resultant steady flow of electrons produce a minute amount of electricity in the form of a direct or DC current. The amount that each cell produces is minuscule, but if you connect a whole batch of cells – in the form of say door-size panels, or tiles on a roof – and use an inverter to turn DC to AC, then you have a relatively simple and inexpensive energy source. The most common stand alone PV systems are designed to clip on to existing roofs. In action you mount the panels on the roof, plug into existing on-grid connection, and the system is ready to go. As to just how well a typical 1000 watt system will perform in the UK, the figures suggest that it will significantly reduce energy costs over the long term. Though photovoltaic cells are rarely seen in the UK – apart from on boats and caravans, and along motorways where they are used alongside mini wind turbines to provide small amounts of power for road signs and the like – they are sometimes used in a small way to power solar collector systems. In this context PV panels are used to provide the electricity that sets the various pumps and controls in motion.

QUESTIONS AND ANSWERS THAT NEED TO BE SORTED

• WHY IS THERE SO LITTLE INTEREST IN PHOTOVOLTAICS ? Apart from the fact that there is a widespread suspicion of any black-box technology where you can’t actually see the wheels turning, PV’s are still relatively high cost.
• HOW ABOUT SIZE AND WEIGHT? So far we haven't been able to pin the various manufacturers down when it comes to weight and size...certainly they are happy to give us the power potential figures of such and such a panel, but as yet they are not so keen on giving the weight and size of the actual panels

And that's about it so far......... exciting isn't it!

THINKING ABOUT A WILDLIFE GARDEN

WHAT IS A WILDLIFE GARDEN?

WHY IS WILDLIFE GARDEN SO IMPORTANT?

Whoever it was that said… that our humanity can in some way be measured by the way that we treat the natural world, must surely have been thinking about wild life gardens. A wildlife garden is place where we – meaning all living organisms, – can meet and come together for the common good. Nature is about balance – like a wheel… and if we get the balance right then everything else will follow. At its most basic level, a wildlife garden is a poison-free environment, an eco-sanctuary for you, for me, for your kids, for plants, for birds…. for all of us.

THINKING ABOUT SOLAR COLLECTORS

When we first became interested in self-sufficiency, people were beginning to experiment with all manner of solar heat collectors - made from old central heating radiators, black plastic tubes, rubber inner tubes, and so on. One system I remember was amazingly simple: water trickled down over a glass-covered galvanized steel roof into a trough and then on into a tank in the cellar, where it was used for hot water and space heating. This system did not look very pretty, and it was a huge free-standing structure almost as big as the side of a house, but for all that it was amazingly efficient, with cold water going in at the top end and too-hot-to-touch water coming out at the other. There was another system where black plastic was wound round and round a massive cylindrical house-high water tank. Just as before, cold water went in at one end and came out hot at the other.

Now we have got to the happy state where commercially built solar collectors are not only available at a very reasonable cost - and the costs are coming down all the time - but moreover they are efficient, sophisticated and generally good, well-designed items. If you want to cut energy costs, and are looking for a simple tried and tested method, then solar collectors are a good option.

All that said we have fitted a thermosyphon vacuum-tube system, or more precisely we have fitted a MICROSOLAR system. Currently this system is so far ahead of other apparently similar systems that it is vital that you are able to tell it apart from its various look-alike clones. The difference is not so much the appearance - because there are superficial similarities - but rather in the technical details. For example, while lots of vacuum solar water heaters of this type look outwardly much the same - they have an array of glass tubes topped by a large cylindrical water tank - the genuine Microsolar system has a patented coaxial multi-valve arrangement that ensures that there is no premature mixing of hot and cold water within the tubes, no overheating, no loss of efficiency on cloudy days, and no extremes when it comes to the range of set-up angles. A genuine Microsolar system will work efficiently at a whole range of inclinations - from 90 degrees right down to 5 degrees to the horizontal. What this means is that this system can be mounted on just about anything from a vertical wall through to a flat roof.

Enough to say that our Microsolar set up has been chugging away very nicely for the last year... its beautiful!

THOUGHTS ABOUT MR FOX

I have just trudged through the snow to check on the geese... its amazing! The snow is covered with hundreds of animal tracks... rabbets, a badger, pheasants, and of course good old Mr Fox. I see that a fox has circled the pen, tried to get under the goose house, taken note of the electric fence, and then backed off. A really good option if you are troubled by a fox and yet dont want to go to the trouble and cost of an electric fence, is to hang tin cans on wires... the fox is really put off if he hears a clatter or sees a movement that he doesnt understand. We have a neighbour who has rigged his chicken run up with an infra red sensor and a camera with a flash... seems like a lot of fun. All that said we reckon that the best defence against the fox is vigilance... lots of visits and constant check-ups on the fence, gate catches, and such. But then again we have two dogs, plus... I do have a very nice shot gun! Bang bang! Not very pretty I know, but.... when needs must!

FEEDING THE GEESE

Its freezing! The whole place is one big snow covered white-out - beautiful but icy and slippery underfoot. I went to feed the geese - so cold. The water supply is frozen solid. I had to bucket water to their trough - not easy. Gill is going through our apple store sorting them for eating and for giving to the geese. I see that there are fox tracks in the snow - easily recognised by the way that the tail drags to give a characteristic swish-swish mark. The geese should be laying in a few weeks time. We reckon to sell the eggs for about £1.10 each - say £6.00 half a doz. So... if each goose lays 50 eggs in a season, and we have 10 layers... 50 x 10 = 500... so 500 x £1.10 = say £500, less the price of their food... Not much money I know, but last year we swapped eggs for logs and for favours. Okay... thats it for now, got to go back to my desk. We are still thinking about the Photo Voltaic PV panels for lighting... perhaps we will have them linked to the lighting circuit. We have got to do our sums.

microsolar

What an amazing item... lots of hot water - even when its covered in snow!