Allotment Gardening Advice Help Chat
Chatting => Design and Construction => Topic started by: Zak the Rabbit on February 01, 2007, 11:09
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Thought i would start a fresh thread to keep the solar and wind apart :?
Ok, so, i have just wired up my solar electric system to my weather satellite system.
The solar panel is a pair of 12v 4W amorphous silicon panels (thats like they use in calculators) rather than the more efficient poly or mono crystalline silicon. This is simply because its cheeper. They are mounted facing south at a 50degree angle towards the sun, in a homemade wood/plastic frame sealed with epoxy resin (fastglass). Both panels have 1N4001 silicon rectifier diodes as protection against reverse current flow (as what can happen when its dark)
The reservoir battery is a Yuasa 12v 7Ahr sealed lead acid. This is simply wired in parallel with the panels and the receiver (ie across the wires)
So, first tests - the weather sat receiver, in its 'standby' mode (not receiving a signal but sound on, scan enabled and squelch open (ie so i can hear the noise)) is drawing 80mA from the system. The solar panel, in bright winter sun is giving 20mA, thats a quarter of the current being taken by the receiver.
in this state, the panel will take 4 times as long to recharge the battery, as the receiver will operate for. Thats pretty good going for a charging system. The system voltage is steady at 13.4v
I was somewhat surprised when wiring it up to find the receiver managed to come on when connected only to the panel, with only a quarter of its required current :shock: it behaved a little erratically, but shows that so long as the equipment being run isnt too ambitious, even a small renewable system is fine.
The next test of the system will be at 11:52, when the receiver activates for a pass by the NOAA-17 weather satellite.
sources - solar panels, bloke on ebay :)
battery, half inched from works skip :wink:
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I understand what you are saying but only because I did physics and maths to a fairly high level many years ago. Not sure the majority of people would understand, but apologies if I am wrong.
Would love it if you posted the occasional project that only required more everyday objects to assemble. As long as you could use it in the garden or shed , of course :lol:
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no problem, anything anyones unsure about just ask,
i will be posting info on how my chicken run is built, just as soon as i have the photos
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ok, so the first full test has been done, and appart from the decoding software being all out of blooming step, so the images have a great big slant to them, it worked fine. The meter reading the voltage has dipped a bit but then steadied off at 12.9v, which is well inside the range at which everything will work ok.
well, ive just finished me garlicy fried spuds with cheese, beans and bacon, so im orf out again now to get on with painting the chicken house frames.
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im the one ,, wot ya ona bout voter .. :roll:
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cor, theres always one! :D
i will try and do it with pictures, its usually better that way.
But not now, its like a spring evening out there, i only popped in to get the camera, so im off out to enjoy it :D
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:? :? :? :? :? :?
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im the one ,, wot ya ona bout voter .. :roll:
not any more you`re not :lol:
i do kinda understand, but i always prefer the " janet and john " editions best :lol: :wink:
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it is a bit tricky to do the simple explanation when theres important technical ideas involved. I will try and make it all really simple :D
when i get round to it... :?
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Ive just put the call out on a dozen or so freecycle sites, for broken or no longer wanted solar powered items, you know like those garden lights. The plan is to get a load of them, strip out the little solar panels, and wire em all together into a BIG solar panel :D
i'll let ya'll know how i gets on
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I didn`t understand all of that but you usually are clear when I ask some dumb question.
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Its actually good practice for me, i want to teach science, so it helps me learn how to pitch the subject matter.
its quite simple really, big solar panels are made up of lots of little solar panels. The ones in the tops of solar garden lights have a voltage of about 2v and a current rating of about 10mA (in good sun)
the voltage is a measure of a power supplies ability to 'push' the current around the circuit. The current is a measure of how many electrons are moving and able to do work. Voltage is measured in volts (v), current in Amps (A), mA is milliamps, or thousanths of an amp, so 10mA is 0.01A
power is measured in Watts (W) and in a DC circuit like this, is worked out by ohms law V x I = P, so these little panels are 2 x 0.01 = 0.02W, or 20mW
now, to be usefull the solar panel needs to give a voltage of 12v to charge a battery, so by wiring 6 of the 2v little panels in series (ie the + lead of one connects to the - lead of the next) we can make it a 12v panel (6x2=12). Trouble is, the current is still 10mA, even though we now have 6 panels. To increase the current, we wire in parallel (ie all + connect together, all - connect together). Lets say we want 100mA, we need 10 panels in parallel (10 x 10 =100), so what we end up with, is a grid comprising 10x6. ten lots of the 6 panel series wired units, wired in parallel.
so a reasonable panel that can charge a battery (albeit only trickle charge at this current) needs at least 60 of the small panels. It starts becoming easy to see why big solar panels are expensive!
Ok, so then we need to charge the battery. Now, lets assume we have a good commercial solar panel, rated 12v 1A (12W!), a typical lead acid battery has a rating of 20Ahr. That means you can take 20A in an hour, or 1A for 20h, before its flat. We also ideally charge the battery at 1/10th its capacity, so if its capacity is 20Ahr, we charge it at 2A for 10hours. So our panel of 1A will take 20hour in good sunlight to completely charge the battery. But! lets say the battery is only used for a light, but lets say for simplicity the light takes 1A at 12v(ie a 12w bulb!), we have the light on for 1hour a day, so the battery goes down 1A in that day, so we only need to charge it for as long as it takes to replace that energy. If it takes 20hour to replace 20A, it will only take an hour to replace the 1A we have used. So one hour of sunlight a day keeps the battery charged.
Of course this is very simplistic, ive assumed simple easy values and assumed good sunlight so the panel always gives its full rated output. In real life, the panel may often be giving lower output (poor sunlight/overcast days) or none at all for aprox half the day (ie at night). At other times the sunlight may be very strong and the panel exceed its ratings. This is where, if you have a big panel, a charge regulator becomes needed, to prevent overcharging the battery. As the sunlight increases in brightness, the voltage and current also increase. Its this increase in voltage above what the battery can handle that leads to overcharging. Current is more of an availability thing, the panel can supply 1A, but if nothing takes that 1A, it doesnt flow. Take as an example you mains electricity, your 100W bulb takes about 500mA, but your supply can give 100A! if all that was forced down your wires it would melt them very quickly!
Of course, if your light or whatever is a lower wattage on your solar setup, say a 5W 12v bulb, the current it takes in use is lower, the battery is less drained, and so it takes less time to restore it to full capacity.
This is why, except very rarely, a solar panel never directly powers anything, its output will tend to fluctuate, is not available at night, and is often too low. Its like drinking water, we get a constant supply from the tap despite the fact that rainfall and riverflow are not constant, due to the storage of water in reservoirs. The battery is your reservoir. And just as water systems have sluiches and valves to keep the reservoir form getting too full, thats what a charge regulator does!
OK, so, what panels are there? well, theres three basic technologies -
Amorphous silicon - brown, like in calculators, not very efficient, not good on overcast days, needs good light. But the cheapest!
polycrystalline and monocrystalline silicon - both blue colour, more efficient and able to keep a good output in poor light, disadvantage is they are more expensive.
My panel is made of a pair of 6"x6" (roughly) amorphous silicon panels.
The other essential is the Diode. This is a little semiconductor eletronic device (like a black cylinder with two wires sticking out) and acts as a one way valve to the flow of current. Each panel has one of these in its + lead, and it stops current flowing back through the panel from the battery or from any other panels its wired to, when the light is poor (which can damage the panel). They are cheep ( a 1N4001 diode is rated at 1A and cost about 3p if that) and small (3mm long ish), but have a slight disadvantage, the lose 0.6v across them. So a 2v panel will be a 1.4v panel on the other side of its protection diode. Because of this, a panel built of lots of smaller ones needs a few extra small panels to account for the loss. But thats preferable to breaking the panel!
for best results from a panel, it would follow the sun around, but such tracking is very expensive. For a simple setup, just get it facing south, at an angle where it will pick up most of the sunlight, say between 30-50degrees (45deg is good :wink: ) mines at about 50.
there we go, a quick introduction to the basic concepts of solar electricity, and a physics lesson thrown in free, gratis, AND fer nowt!, what more could ya want? :D :D
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Much clearer to my small female brain,yourfingers must beshorter tho`.
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Ive just put the call out on a dozen or so freecycle sites, for broken or no longer wanted solar powered items, you know like those garden lights. The plan is to get a load of them, strip out the little solar panels, and wire em all together into a BIG solar panel :D
i'll let ya'll know how i gets on
Did you get any free PV gear offered yet? Just wondered how generous people are.
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Sadly no, one chap had two of them but the distance was prohibitive to collecting them,
still, it was worth asking just to find out :)
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Its actually good practice for me, i want to teach science, so it helps me learn how to pitch the subject matter.
If you are serious, I hope you don't mind me tearing this to shreds, as per *my opinion* :). This kind of language may well do for people who are never going to hold a screwdriver, and therefore don't really need to know anything about it anyway, but let's not screw things up for those who might want more later!
(mini rant!!! ? - it's been a while since I've done one of them :). Must be a side-effect of my old physics teacher who was a stickler for accuracy - and getting things right!)
its quite simple really, big solar panels are made up of lots of little solar panels. The ones in the tops of solar garden lights have a voltage of about 2v and a current rating of about 10mA (in good sun)
will let you off there, if your not teaching basic English! It's.
the voltage is a measure of a power supplies ability to 'push' the current around the circuit. The current is a measure of how many electrons are moving and able to do work. Voltage is measured in volts (v), current in Amps (A), mA is milliamps, or thousanths of an amp, so 10mA is 0.01A
Well, voltage is defined as a measure of the amount of energy carried per unit of charge... [Eng]a power supply's[Eng] - measured in Volts (V) when using the SI system of units. Current is the rate of flow of charge - which may or may not be electrons.
power is measured in Watts (W) and in a DC circuit like this, is worked out by ohms law V x I = P, so these little panels are 2 x 0.01 = 0.02W, or 20mW
Power is the 'rate' of energy - and is watts in the SI system when using joules per second. Ohm's law {Eng!} is 'In a metallic conductor at a constant temperature, the potential difference across it is proportional to the current through it'. In the SI system this can be represented by the equation V=IR (still only in a metallic conductor at constant temperature) since the definitions of quantities are chosen to keep it simple. (This is nothing to do with power...). In an AC circuit the same law applies.
now, to be usefull the solar panel needs to give a voltage of 12v to charge a battery, so by wiring 6 of the 2v little panels in series (ie the + lead of one connects to the - lead of the next) we can make it a 12v panel (6x2=12). Trouble is, the current is still 10mA, even though we now have 6 panels. To increase the current, we wire in parallel (ie all + connect together, all - connect together). Lets say we want 100mA, we need 10 panels in parallel (10 x 10 =100), so what we end up with, is a grid comprising 10x6. ten lots of the 6 panel series wired units, wired in parallel.
OK, but practically speaking a 12V battery needs more like 13.9V to charge it - so add another little panel. Useful!
so a reasonable panel that can charge a battery (albeit only trickle charge at this current) needs at least 60 of the small panels. It starts becoming easy to see why big solar panels are expensive!
Ok, so then we need to charge the battery. Now, lets assume we have a good commercial solar panel, rated 12v 1A (12W!), a typical lead acid battery has a rating of 20Ahr. That means you can take 20A in an hour, or 1A for 20h, before its flat. We also ideally charge the battery at 1/10th its capacity, so if its capacity is 20Ahr, we charge it at 2A for 10hours. So our panel of 1A will take 20hour in good sunlight to completely charge the battery. But! lets say the battery is only used for a light, but lets say for simplicity the light takes 1A at 12v(ie a 12w bulb!), we have the light on for 1hour a day, so the battery goes down 1A in that day, so we only need to charge it for as long as it takes to replace that energy. If it takes 20hour to replace 20A, it will only take an hour to replace the 1A we have used. So one hour of sunlight a day keeps the battery charged.
Yuk. At first I thought it was a typo (generous :) eh?) but then you do it twice more! How does a battery 'go down 1A' - is this a new measurment of distance? Has it sprung a leak? Certainly 1Ah of energy is used from the battery. and that 1Ah wants replacing, and at 1A it would take 20 hours to supply 20Ah of energy...
Of course this is very simplistic, ive assumed simple easy values and assumed good sunlight so the panel always gives its full rated output. In real life, the panel may often be giving lower output (poor sunlight/overcast days) or none at all for aprox half the day (ie at night). At other times the sunlight may be very strong and the panel exceed its ratings. This is where, if you have a big panel, a charge regulator becomes needed, to prevent overcharging the battery. As the sunlight increases in brightness, the voltage and current also increase. Its this increase in voltage above what the battery can handle that leads to overcharging. Current is more of an availability thing, the panel can supply 1A, but if nothing takes that 1A, it doesnt flow. Take as an example you mains electricity, your 100W bulb takes about 500mA, but your supply can give 100A! if all that was forced down your wires it would melt them very quickly!
Unnecessarily simplistic and often wrong! You have the good idea of illustrating a 12W bulb on a 12V system taking 1A, and therefore using 1Ah in an hour. Keep hold of this basic idea (energy) and that covers all the variability of night, shade, etc. since your solar panel just needs to produce 1Ah of energy to recharge the battery! This can be the peak output of the panel for 1 hour, or half-power for 2 hours etc.
Increasing light does not necessarily increase the output power, voltage or current of PV panels. They have an 'open circuit' voltage rating which is the maximum voltage they can produce (some light under no load). This will be reached quite quickly even in dim light since it is a function of the physics of photons and matter. It may be affected by shading of parts of the panel (and cloudiness). Panels also have a rated 'short circuit' current - what they will deliver if you connect the + and - together in full light. The current will increase with increasing light upto near this level, but not go above it. The rated power is derived from the optimum particular balance of voltage and current the panel is designed to deliver. Thus a panel may be Voc=44V, Isc=5.12A, yet be rated at 180W since its peak output is at Vmppt=37V Imppt=4.86 (mppt=maximum power point)
It is not the excess voltage/current of the panel caused by excess light that causes the need for a charge regulator - it is simply the balance between energy put in against energy taken out. If your panel cannot produce enough energy, your battery will eventually go flat. So you need a panel that can produce more than you use! The charge regulator simply disposes of any surplus energy from the panel when the battery is charged. It should also increase the efficiency of the panel by letting the panel run at its Vmppt and Imppt - and transforming these to a lower ideal battery charging voltage at slightly higher current. (12V nominal PV's are often 17Vmppt, and connecting them directly to a 12-13.8V battery wastes that surplus energy potential.)
Of course, if your light or whatever is a lower wattage on your solar setup, say a 5W 12v bulb, the current it takes in use is lower, the battery is less drained, and so it takes less time to restore it to full capacity.
If it is a 5W bulb, it doesn't matter what voltage it is - it will take 5W. Turn it on for an hour and it has used 5Wh! If the PV panel puts out 5W for 1 hour (or 2.5W for 2h etc.) this will be 5Wh and cover the energy used.
This is why, except very rarely, a solar panel never directly powers anything, its output will tend to fluctuate, is not available at night, and is often too low. Its like drinking water, we get a constant supply from the tap despite the fact that rainfall and riverflow are not constant, due to the storage of water in reservoirs. The battery is your reservoir. And just as water systems have sluiches and valves to keep the reservoir form getting too full, thats what a charge regulator does!
Nothing before the 'this is why' is the reason! Why not just a plain statement of 'A solar panel rarely... because...' ?
OK, so, what panels are there? well, theres three basic technologies -
Amorphous silicon - brown, like in calculators, not very efficient, not good on overcast days, needs good light. But the cheapest!
Work better on overcast days
polycrystalline and monocrystalline silicon - both blue colour, more efficient and able to keep a good output in poor light, disadvantage is they are more expensive.
Not very good on overcast days Polycrystaline are blue, monocrystaline are charcoal.
4th type is 'hybrid' - expensive but good in both overcast conditions and strong light - and expensive, of course! :)
My panel is made of a pair of 6"x6" (roughly) amorphous silicon panels.
The other essential is the Diode. This is a little semiconductor eletronic device (like a black cylinder with two wires sticking out) and acts as a one way valve to the flow of current. Each panel has one of these in its + lead, and it stops current flowing back through the panel from the battery or from any other panels its wired to, when the light is poor (which can damage the panel). They are cheep ( a 1N4001 diode is rated at 1A and cost about 3p if that) and small (3mm long ish), but have a slight disadvantage, the lose 0.6v across them. So a 2v panel will be a 1.4v panel on the other side of its protection diode. Because of this, a panel built of lots of smaller ones needs a few extra small panels to account for the loss. But thats preferable to breaking the panel!
'cheep? ' Am I back on the poultry pages??? :) Congratulations on saying 'voltage accross'. A parrot probably would 'voom' if you put 4 million volts across it!
for best results from a panel, it would follow the sun around, but such tracking is very expensive. For a simple setup, just get it facing south, at an angle where it will pick up most of the sunlight, say between 30-50degrees (45deg is good :wink: ) mines at about 50.
[Eng]mine's[Eng]
There is only a few percentage points of loss at SSE or SSW orientation. 40deg is probably better, especially with mono/poly which will really gobble up the late spring to early autumn sunshine on 23rd August each year.
there we go, a quick introduction to the basic concepts of solar electricity, and a physics lesson thrown in free, gratis, AND fer nowt!, what more could ya want? :D :D
And don't take offense, please, but the physics lesson was a bit dodgy. Glad I didn't pay for it! :D. If you want to teach the stuff, teach it right from day one.
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cheers for that, and only at midnight :D im on shift for another 8hours.
ive no problem with constructive critisism, but a couple of points -
1. accuracy isn't important in this topic
2. i dont have time to proof read everything
3. this was aimed to put across a technical subject matter to non-techinical people without losing essential data
i could have written it in ladybird book language, or equally well as a BSc or MEng essay but much of the info wasn't required.
Incidentally, ohms law does not apply fully to an AC circuit except where that circuit is purely resistive, but as all AC circuits contain some inductance and capacitance and are therefore reactive, account must be taken of the reactance at the specific frequency of operation, which ultimately would lead us to require definining values of impedance and hence the use of j notation and phasor information, and for power calculations the circuits power factor would need to be calculated.
hey,ho, back to keeping the nations TV transmitters operating tonight...
:D
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Bleeding heck ... heavy stuff. One of my Physics lecturers at Uni was Prof R V Jones, http://en.wikipedia.org/wiki/Reginald_Victor_Jones
His lectures were much more fun ... :wink: :D
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old RVJ certainly knew his stuff, :)
great man, much of what i work with now is descended from work he did
so, WG, you wouldnt like a dissitation on chemoelectric atmospheric absorption interactions, surface insolation and planetary albedo to keep you awake?
how about chloroplastic pigmentation and mitochondrial electron transport in dinucleotide catabolis?
:lol: :lol: :lol:
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cheers for that, and only at midnight :D im on shift for another 8hours.
ive no problem with constructive critisism, but a couple of points -
1. accuracy isn't important in this topic
2. i dont have time to proof read everything
3. this was aimed to put across a technical subject matter to non-techinical people without losing essential data
More of my opinion(!) :
1. Accuracy is important if you are informing others. While you may know you are being loose, the uninitiated do not know and will end up learning your inaccuracy, and then having to unlearn it or think they are wrong/useless when they get things wrong as a consequence.
2. Practise being right first time!!!
3. If the people are non-technical and not likely to progress in the subject, then the jargon/technicality is ultimately irrelevant to them, but you can still choose to give it right/accurate. This will benefit others as per point 1.
i could have written it in ladybird book language, or equally well as a BSc or MEng essay but much of the info wasn't required.
In ladybird language:
I want a 12W bulb on for 1 hour a day. Therefore I need 12Wh of energy per day.
This can come from supplying 12W for 1 hour, or 6W for 2 hours etc.
I have a 12V car battery to use as an energy store.
Since Watts=VoltsxAmps, in a 12V system I am getting 12W at 1Amp, or 6W at .5Amps etc. Thus to get 12Wh I need a current of 1A for an hour, .5A for 2 hours etc.
My solar cells are 2V, so I need to string 6 of them together to reach 12V (like you put 4 x 1.5V batteries in a radio to supply 6V)
These little cells only produce 10mA (=.01A). .01Ax12V=0.12W. So they would need to be on for 100 hours to produce 12Wh. Not very good. By adding more strings of 6 cells, each capable of providing 10mA, we can increase the power. 10 such strings would provide 0.1A. Now we only need 10 hours to produce 12Wh.
etc.
Incidentally, ohms law does not apply fully to an AC circuit except where that circuit is purely resistive, but as all AC circuits contain some inductance and capacitance and are therefore reactive, account must be taken of the reactance at the specific frequency of operation, which ultimately would lead us to require definining values of impedance and hence the use of j notation and phasor information, and for power calculations the circuits power factor would need to be calculated.
OK! :) So you do know what you are talking about!!! Don't let yourself down with sloppy writing, then :)!
hey,ho, back to keeping the nations TV transmitters operating tonight...
:D
Thanks, but the listen again facility on BBC7 keeps me going - all those 'I'm Sorry I haven't a Clue', 'Burkiss Way', 'Goon show', Poirot, Marple, Holmes.... - good old quality radio :D
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old RVJ certainly knew his stuff, :)
great man, much of what i work with now is descended from work he did
He was my favourite lecturer 'cos he was so human. Had us all in stitches describing how they employed guys simply to carry sheets of glass around the radar research facility - that's all they did, no other purpose than to confuse any spies who might be watching.
so, WG, you wouldnt like a dissitation on chemoelectric atmospheric absorption interactions, surface insolation and planetary albedo to keep you awake?
how about chloroplastic pigmentation and mitochondrial electron transport in dinucleotide catabolis?
Awwh, I was just going to say that! (I never thought I'd see a posting which had more unknown words than one of Muntjac's)
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Hi Zak,I have used a square monocrystalline panel approx 18x18 inches to recharge some free 12v rechargeable batteries from a golf buggy-not sure what Ah these are rated at...but it charges them efficiently to run my fishfinder/bilges which is ideal as i like to keep my engine/spare batteries free from any other for safety.
this panel was got from a well known internet buying/selling site for a measly £6.00 plus postage.
apologies as i can't tell anyone anything about the technicalities of electrics.
thanks rnl
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Everything that has been said here has gone completely over my head. I don't have a scientific mind unfortunately :oops:
However, I hope this doesn't sound silly, but I am interested to know if you could basically power your shed with solar energy. All I ever see it used for is lighting, but what about heating or running heated propagators off it?
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went straight through my ears too! however, I power my shed with a petrol genny, less than 40 squids and runs anything I need to use.
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Glad I'm not the only one :oops:
I imagine that might be abit noisy, the generator I mean. My shed is at home right next door to my neighbour's house. Not sure they would be to pleased with the droning of the genny...
Good idea though if on an allotment site.
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Glad I'm not the only one :oops:
I imagine that might be abit noisy, the generator I mean. My shed is at home right next door to my neighbour's house. Not sure they would be to pleased with the droning of the genny...
Good idea though if on an allotment site.
Break into their house and run a spur from their mains :roll: I am sure Zak would give you the tech details. :wink:
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You know Aidy, you could be a very bad influence on me :twisted:
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I'm no genius with this subject but bear with me.
The solar panels would just about power the light but that's about it I think.
On 'It's not easy being green' the Strawbridges powered a fan in their greenhouse from a solar panel and battery to circulate warm air stored during the day in a heat sink. Very clever idea.
It's only for low power stuff. On boats they use them to help charge batteries I think.
I think Aidy's idea is favourite. 8)
Rob
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I saw some of those programmes, very good but utterly beyond me I think.
Thanks for the info
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Likewise. Unless you have a healthy bank balance to fund the cheap living :)
Rob
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I`ve been watching a programme on "Discovery" called "Planet Mechanics".
Basically, one of the blokes from scrapyard challenge(with the big moustache), and another bloke go to different places to help set up free energy devices for people. On this one episode, they had to come up with an idea for powering a boat that was able to carry 6 paying passengers for a hotelier in Venice and they decided to go with solar power. It had about 6 4X2 panels as a canopy which charged some batteries and they in turn powered an electric outboard motor. The motor was bought from a supplier, it wasnt the fastest, but it did a very good job, but they had to continuously alter the angle of the canopy to get the best angle to catch the sun to make sure the batteries kept a good charge.
They then built an electric speed boat for the hotelier, granted it was small, but it worked very well and went quite fast. They used a different motor than the one on the other boat, they converted an electric Go-kart motor into an old outboard shell to work better. But I dont think the batteries were solar powered though.
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I presume the moustached bloke was Dick 'The Walrus' Strawbridge :)
Were the solar panels economical, ie would they pay for themselves through fuel savings or was it just an exercise in eco-transport ? (or did they choose to ignore the cost?)
It irks me that a lot of these resources are good if you have plenty of dosh to throw at them but for us poorer folk we're stuck with the dirty, smelly cheap alternatives.
If there were subsidies, we could all be eco-warriors 8)
Rob
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I`m not sure on the price of the solar panels, so cant say about the savings, because it was more about polution prevention rather than being cost effective. The programme was based on the idea that the polution from the engines was damaging the city ie:- the fumes coroded the buildings, and the motors (which seemed to be all 2 stroke) poluted the water.
They showed that the motor polutes the water by putting a 2 stroke outboard
into a barrel of clean water and running it for 5 mins..... there was oil all over the side of the barrel and floating in the water.
I know they could have used a leaky old motor to emphasize their point but there will be engines like that running about.
The idea was to be self sustaining, and not to use mains electric to charge the batteries, because of the polution thing again
I would imagine that the panels they bought would cost a few bob, as would the electric motors.....they never scrimp on these shows do they, they always buy the most expensive.
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As you say, a lot, if not most of engines will be clapped out and hard working. The idea behind it is sound but it is still very much a rich man's prerogative.
Similarly, when they brough tin the emissions test with the MOT, it was the older cars owned by less well off drivers which failed, while the people who could afford to replace their cars frequently sailed through.
It would be nice if the poorer folk could take part in reducing emissions and using cleaner options but sadly they are stuck with the old technology.
Such is life I guess.
Rob
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I watched a new (to me) episode of planet mechanics today, they used the force of the sea to create power for a surfers caravan.
Hmmmm....now there I was, thinking it was educating me as to the possibilities of Joe public harnessing free energy in one way or another, but now I`ve changed my mind. It seems its educating me in to believing that its not a feesable thing to do in reality.
They spent days and days building and erecting this thing and got very little power out of it...enough to light some fairy lights around the door of the caravan. There was no explanation of AC and DC types of electric, no cost comparison, no thought of using other types of power (wind would have been a good one for where they were).
Now "Rough Science", I`ve learned a thing or two from that....like kate humble looks nice in a rubber wetsuit :lol:
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i got given a mini fridge for a birthday a while back, and currently has been gathering dust in the attic for the past and a bit due to having no where to use it. however having just taken on an allotment near to work and will hopefully get to put a shed up soon, i was wondering if it is possible to out a solar panel on the roof (south facing) and then wire it up to power the fridge. and then i can can enjoy a cold beer after many hours digging.
cheers for any help
paul
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From what i`ve been told, (and I`m sure someone will put me right if its wrong)
You cant store AC electric, which is what your fridge will run on, like any household units. You can only store DC electric, and to do this you need to store it to a battery, but this in itself will not run your fridge, I think you need to get something to convert the DC into AC, but not sure of what to get or how to set it up.
It can be done, but may be quite costly to do so, may be best to buy a specific fridge to run off DC power and do it that way...even though that wont be cheap either.
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I think some of the mini fridges do run off DC. We had a camping one that ran off calor gas too.
But would a reasonably priced solar panel give out enough oomph (technical term) to power a fridge, bearing in mind it's probably going to be running at least 30% of the time (total guess) ?
can you find the wattage conxumption on the back of your fridge paul ?
I'll leave to the bods to tell you if it's possible.
Rob