Average sunlight hours / solar bird bath?

[britbird]

Hello all
please be a little gentle, if I am not up to the mark in terms of etiquette on this forum - first time for me!
I have two questions.
Firstly, we are in Shropshire (UK) and I want to know how much PV output to expect from an installation of a 4KWh panel system we are looking to purchase - is there a table of 'average sunlight hours' I can get?
Second - I am fed up with the water freezing in our garden bird bath - can I get a tiny PV panel and an immersion heater element and fit them simply to a bird bath?
Probably stupid questions, but I am a bit - so thank you, if you can help.

[martin]

Hello and welcome to the forum for a start!
You'll be inundated with answers on the first part, I'll have a go at the second - an immersion heater element as usually known would require a simply enormous pv array to ensure it's operation in the depths of winter (sod's law is that when you most need heat, pv production is at it's minimum)  - you could go for a low wattage fish tank heater, which I'm sure you'd be far better running off  the mains - for even a tiny heater like that you'd need a thumping great battery (or three), charge controller and quite a lot of pv panels - you'd be in the over a thousand quid area to "do it properly" using pv. As a general rule of thumb, it is usually unwise to use electricity for heating where there is another alternative - it's best to use electricity for those things that no other power source can provide... Only other thought is that you might adopt some "sideways thinking" and use a fish tank "bubbler" or circulation pump to stop it freezing (but it would eventually if it got cold enough)

[britbird]

Thank you Martin
Yes that makes sense, I didn't think about the time of year etc - not much sun in Feb! the cost is prohibitive too, so any solution considered, I agree about the bubble (good idea though) so is there an immersion heater (probably only need a tiny amount of heat) that runs on batteries, so I can re-charge them in the house - hopefully get some PV sun in the winter! - I can make the bird bath into a drinker in the winter and keep the water covered and insulated as best I can, with just a small hole in the top for the birds to drink from?
David

[martin]

It's probably going to be cheaper to run a mains cable - just to illustrate what we're up against - if you used a 25 watt fish tank heater that was "on" for arguments sake half the day, in a 24 hour period that'd use 12x25 watt hours = 300 watt hours - so in a day you'd be taking 25 amp hours out of your 12v battery, so ideally you'd need at least a 100 amp hour deep cycle battery, preferably double that..... (probably £150-worth or more) - howsabout the base off a mini hurricane lamp or similar and heat it with paraffin?

[britbird]

Yes, that's got me thinking, maybe a tea light candle (not sure how long they last) they are cheap and plentiful and if I insulate it really well it should work a bit like a thermos flask and keep the heat in after the flame has expired, in fact a tea light candle is probably too much heat - need something slower burning and longer lasting?? - the bird drinker could be small enough to bring in at night time, so only needed to be heated for 6? hours in the day time.

[martin]

We use a very pragmatic and simple method - the bird bath is a few step from the back door - when we feed the birds we take out a kettle of hot water that's been sitting on the Rayburn and melt the ice with that, and then repeat throughout the day when necessary....

[britbird]

Thank you for your help Martin, as I have not heard from anyone else about the average sunlight - could you help me on that too?
I want to get a feel for how much production I can expect over a year and compare that to our existing electric usage - I dare say production is different for the different type of panels etc, which is why I want to be able to quote an amount of sunlight to the company quoting me and see what they say we can expect back in terms of production.
Many thanks

[A.L.]

hello and welcome britbird,

if you have not got to the point of getting quotes, which should include output estimates, then if you have a reasonable site between south-east and south-west and little shading, a full 4kWp system should give around 3400kWh/year and perhaps a little more.

[dhaslam]

If you could bury a small pipe underground and  circulate water  through it  and the bird bath when the  temperature approaches zero it should be able to  keep the water from  freezing and  in any case  moving water won't freeze.  It would onlly take a small battery to power the pumpbut it would need to be recharged fairly frequently  in cold weather.    

I have the same problem on a bigger scale.   I want to have a floating island for birds on a pond but foxes could cross the ice.   There will be  a 75 metre underground pipe to the pond so I am  hoping that   if the pipe end is just under the island it will clear a patch of water around it.  

[Justme]

What about using one vacuum tube & a bit of plumbing to make a thermosyphon set up?

Or if designing the bird bath from scratch have the tub fitted so the bulb enters the bottom of the bath, but within an area that is protected from draining down & the birds.

[JohnS]

Firstly, we are in Shropshire (UK) and I want to know how much PV output to expect from an installation of a 4KWh panel system we are looking to purchase - is there a table of 'average sunlight hours' I can get?
 

The Met office publish historic sunshine hours data:

http://www.metoffice.gov.uk/climate/uk/stationdata/

PVGIS gives a good estimate of PV production for Europe.

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php#

Everyone tends to use the standard 14% losses and in the monthly production reports, more often than not, production is higher than the PVGIS estimate unless it is a particularly dull month.

John

[acresswell]

If you go for the bubbler idea, but stick the air pump somewhere warm-ish then that will help.  We used to put the air pump in the greenhouse to stop our pond freezing.  Those little pumps will pump down a surprisingly long length of hose...

[Baz]

Someone published on here a years PV output data in a spreadsheet. I didn't record who when I saved it but the last entry is 15/5/11 so must have been after then, and probably in the pv section.
Then also there is Dhaslam's spreadsheet of solar water output for a year+ published sometime about 7 november last year.
I keep mentioning these and not noting exactly where they are. They are real reference works so should be put in some data file section.

[MarkB]

PVGIS gives a good estimate of PV production for Europe.

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php#

Everyone tends to use the standard 14% losses and in the monthly production reports, more often than not, production is higher than the PVGIS estimate unless it is a particularly dull month.

This should really give a pretty good estimate of the average energy output of a panel over a year. Go for the Climate-SAF model in the web form to get the best estimate. Note that the actual results will vary month by month and year by year, but as an average it's probably fairly close.

[MR GUS]

OP, whilst this may not be solar, or even in our own country, it does show that there are various options & distributors of the product you are trying to sort.

I was merely browsing for cat / dog / bird heat pads & this place came up! ..so it is do-able.
other members may wish to comment.


http://www.drsfostersmith.com/1/3/bird-bath-heated


http://www.drsfostersmith.com/1/1/1841-bird-bath-de-icer.html