owen-cox
Well-Known Member
I think solar gets you more power anywhere generally. I can think of many windless days but not many when it didn't get light.
12 volt coolbox could it be run off a solar panel....
- Thread starter Wansworth
- Start date
thesaintlyone
Well-Known Member
Everytime Solar Power gets mentioned on this forum out come the usual quips and naysayers about how it wont be efficient in the UK and is only useful for those in sunnier parts of the world
So I thought I would do a bit of googling for you.
http://www.greenmatch.co.uk/blog/2014/07/is-the-uk-sunny-enough-for-solar-panels-to-work
And that isnt the only source
We get 60% of the suns energy similary found at the equator.
I have a small 25w panel and not once have i returned to my boat and found the battery dead the lights not working my phone not charging or my hand held VHF with no power.
If you have greater uses then you can do a few things.
Buy a panel big enough to suit your outputs 100w mono Flexible panels as I mentioned before will quite happily lay on your cabin top no mounting required
and cost about £120
An LCD Meter Controller Costs about £20 and will give you all the info required.
Wiring is simple twin core as found in your local chandlery and runs from the panel to the controller and from the controller to the negative and positive terminals on your house battery.
Easy to rig up even I managed it ?
Buy more energy efficient products.
So I thought I would do a bit of googling for you.
http://www.greenmatch.co.uk/blog/2014/07/is-the-uk-sunny-enough-for-solar-panels-to-work
And that isnt the only source
We get 60% of the suns energy similary found at the equator.
I have a small 25w panel and not once have i returned to my boat and found the battery dead the lights not working my phone not charging or my hand held VHF with no power.
If you have greater uses then you can do a few things.
Buy a panel big enough to suit your outputs 100w mono Flexible panels as I mentioned before will quite happily lay on your cabin top no mounting required
and cost about £120
An LCD Meter Controller Costs about £20 and will give you all the info required.
Wiring is simple twin core as found in your local chandlery and runs from the panel to the controller and from the controller to the negative and positive terminals on your house battery.
Easy to rig up even I managed it ?
Buy more energy efficient products.
ex-Gladys
Well-Known Member
+1... Never regretted for a minute going solar rather than wind in the UK. Keeps my 330AH domestic bank bang up to snuff on a swinging mooring
TSB240
Well-Known Member
We used to use a peltier type cool box on our trailer sailer. We had solar but found that we rarely bothered plugging the box in as the cooling is so ineffiecient. I found filling the bottom of the box with Ice from home freezer or bought ice from super market was most effective. This will keep virtually everything at 4 degrees max for up to two days except in a heat wave!
We have carried on doing this with our converted cool box on our new boat.
We will freeze a bottle of water and a cartoon of orange juice during the week. No need to use any electricity for two days to keep well insulated cool box below 4 degrees. After a couple of days the small amount of engine use we do is enough to chill the cool box back down But a peltier would never do this. Better to stop off at any supermarket and get another £1 bag of ice!
We have carried on doing this with our converted cool box on our new boat.
We will freeze a bottle of water and a cartoon of orange juice during the week. No need to use any electricity for two days to keep well insulated cool box below 4 degrees. After a couple of days the small amount of engine use we do is enough to chill the cool box back down But a peltier would never do this. Better to stop off at any supermarket and get another £1 bag of ice!
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whiteoaks7
Well-Known Member
Don't think Amps think Watts. Look at the badge on the cooler which will tell you how many Watts it requires when it's running.
Then read here: http://www.pbo.co.uk/expert-advice/solar-panels-everything-you-need-to-know-24455
Then read here: http://www.pbo.co.uk/expert-advice/solar-panels-everything-you-need-to-know-24455
ghostlymoron
Well-Known Member
That's a very interesting article. I'm a bit baffled by the tracking aspect. I you have panels at a fixed angle of say 15°, when you're sailng towards the sun, it's helping, if you're sailing away, it's reducing the insolation rate. Seems to me you'd need to constantly fiddle with them to get any added efficiency. My approach is to mount my panel where it is convenient on a fixed mount and accept that it's less efficient but still producing useful and free power.
macd
Well-Known Member
Mine, too, ghostly, but then we have room for enough panels (340W, in an area not heavily shaded) to compensate. Plus we've made considerable efforts to reduce our electrical consumption (LEDs, keel-cooled fridge, etc. I shudder to think what each chilled G&T costs, calculated against capital outlay - except that the more you drink, the less the unit cost...)
I can certainly see the sense in making panels adjustable where there is limited room to fit them, although it will usually demand a degree of ingenuity and extra expense.
ghostlymoron
Well-Known Member
I don't see that tilting them about the horizontal axis will work for me as sometimes I'm heading towards the sun and sometimes away from it.
macd
Well-Known Member
Wouldn't that depend on which horizontal axis you're talking about?
One reason I suggested it could be tricky/expensive was that the ideal is panels tilting in two planes.
PaulRainbow
Well-Known Member
My aft panel is on a pole. The panel tilts on one axis, but the pole also rotates so it can always be angles towards the Sun. Ask me how often i mess around tilting and rotating it.
William_H
Well-Known Member
Back to the original question. The cool box will draw a specific current like 4 amps usually continuous.
Now a solar panel connected directly to the coolbox or any other device will produce a voltage depending on the wattage rating of the panel and of course the sunshine level. So a 4 amp coolbox might be best run on an 80 watt panel. This in bright sun will probably pull the panel voltage down from 20volts open circuit to perhaps 17 or 18 volts maybe less. This higher voltage may well smoke the coolbox. A 50w solar panel will probably not provide the desired current but the voltage will fall to a level closer to 12v or maybe less. A higher powered panel say 100w will tend to provide the current but at a voltage much too high for the device. It will tend to push a higher current in so overpowering the device.
So the only safe way to run any 12v nominal device on a solar panel is to start with plenty of power rating of the panel then fit a buck regulator to always hold the voltage closer to the 12v required. Something like this might do but a higher current rating would be safer. http://www.ebay.com/itm/DC-DC-4-38V...007557?hash=item4889f25d85:g:4fIAAOSw5VFWOdwr olewill
Now a solar panel connected directly to the coolbox or any other device will produce a voltage depending on the wattage rating of the panel and of course the sunshine level. So a 4 amp coolbox might be best run on an 80 watt panel. This in bright sun will probably pull the panel voltage down from 20volts open circuit to perhaps 17 or 18 volts maybe less. This higher voltage may well smoke the coolbox. A 50w solar panel will probably not provide the desired current but the voltage will fall to a level closer to 12v or maybe less. A higher powered panel say 100w will tend to provide the current but at a voltage much too high for the device. It will tend to push a higher current in so overpowering the device.
So the only safe way to run any 12v nominal device on a solar panel is to start with plenty of power rating of the panel then fit a buck regulator to always hold the voltage closer to the 12v required. Something like this might do but a higher current rating would be safer. http://www.ebay.com/itm/DC-DC-4-38V...007557?hash=item4889f25d85:g:4fIAAOSw5VFWOdwr olewill
ghostlymoron
Well-Known Member
A small 12v battery would also regulate the voltage. And provide some overnight capacity (if necessary).
PaulRainbow
Well-Known Member
No, it won't. If a high wattage panel is fitted it needs a regulator.
ghostlymoron
Well-Known Member
I have always fitted a cheap regulator even on a 10w panel.
PaulRainbow
Well-Known Member
Indeed, but in your previous post you said "A small 12v battery would also regulate the voltage". Which is obviously not the case, or you wouldn't have fitted regulators to 10w panels
rogerthebodger
Well-Known Member
Indeed, but in your previous post you said "A small 12v battery would also regulate the voltage". Which is obviously not the case, or you wouldn't have fitted regulators to 10w panels
Generally it is considered that if the solar panel wattage is less or equal to 10% of the battery Ah a regulator is not needed.
Back to the OP question, if he was considering just connection any size solar panel direct to a 12V coolbox IMHO that would be unwise. IMHO is would need a battery to even the load and a regulator to prevent the battery from being cooked. In theory you could set it up without a regulator but the battery could be over charged and of cause there would be no cooling over night or a overcast days particularly in the UK.
