solar - something for nothing

[emlclcy]

On a hot sunny day your solar panel is producing say 100watts. You cool the rear of the panel down from say 40deg to 5deg, does the output increase?

If so by how much roughly?

[KJT]

Yes, they are affected by temperature.

 

https://www.teachengineering.org/collection/cub_/lessons/cub_pveff/Attachments/cub_pveff_lesson02_fundamentalsarticle_v6_tedl_dwc.pdf

 

Page three gives some calculations.

 

My personal view is that any solar is better than none. If you can have some sort of air gap underneath the panels that would be beneficial. Tilting them would give two benefits, both for cooling and being angled towards the sun for greater efficiency.

 

Ken

[emlclcy]

well my thinking is if you had a small say 12v low power water pump circulating canal water over the panel would the output go up more than the water pump takes?

sort of something for nothing

[MtB]

"solar - something for nothing"

 

Or more accurately, this time of year, nothing for something.

 

To be precise, I'm getting about typically 0.2 Amps out of my 200W of solar into my 24v battery bank. Awesome!

 

...not!

[Wanderer Vagabond]

"solar - something for nothing"

 

Or more accurately, this time of year, nothing for something.

 

To be precise, I'm getting about typically 0.2 Amps out of my 200W of solar into my 24v battery bank. Awesome!

 

...not!

 

This rather sums up my issue with solar on boats. During the summer season I like to travel around so top my batteries up naturally whilst I'm doing so. During the winter months when the weather is perhaps not so good I wouldn't mind staying places for longer but that is when solar doesn't really do much. I am generally pro-Solar having fitted them to my house, but on a boat? How long would it be before I got any return on the investment? (fuel saved versus cost of installation)

[bizzard]

I'm investigating Lunar rays at the mo to make lunar panels for the generation of electricity which should help quite a bit especially during the winter and at any time of the year when the moon comes around. My experiments are showing great promise. That's all the information I'm able to impart for the time being as the research and highly technical method is top secret. I can however impart some little clues to the world though, and they are, strings, fresian, feline, Lear, and last but not least, cheese.

[Wanderer Vagabond]

I'm investigating Lunar rays at the mo to make lunar panels for the generation of electricity which should help quite a bit especially during the winter and at any time of the year when the moon comes around. My experiments are showing great promise. That's all the information I'm able to impart for the time being as the research and highly technical method is top secret. I can however impart some little clues to the world though, and they are, strings, fresian, feline, Lear, and last but not least, cheese.

Sounds Moonshine to me

[Jess--]

This rather sums up my issue with solar on boats. During the summer season I like to travel around so top my batteries up naturally whilst I'm doing so. During the winter months when the weather is perhaps not so good I wouldn't mind staying places for longer but that is when solar doesn't really do much. I am generally pro-Solar having fitted them to my house, but on a boat? How long would it be before I got any return on the investment? (fuel saved versus cost of installation)

How useful solar is will all boil down to what you need from it.

 

for a CCer using minimal power & moving every day (or couple of days) they will give a minimal benefit during the summer (due to the batteries being charged anyway through engine use) and be next to useless in the winter.

 

for a liveaboard on a permanent mooring they will be extremely useful during the summer (possibly removing the need to run the engine completely) and may help a little during the winter.

 

for a leisure boater like myself (currently) they are extremely useful whatever the season simply because it (almost) removes the need for a regular battery charging regime while the boat is not in use and negates the need for a mains hookup while idle in the marina.

[Nickhlx]

Don't rubbish lunar illumination !! A guy I know was baffled by his kit reporting the production of electricity at night and it was indeed the illumination from the moon ! Apparently these days some panels have such good low light response that they will produce electricity at night - roll on advances in solar panels .

 

Nick

[David Mack]

Sounds Moonshine to me

Hey, it sounds like Bizzard's been diddled (more than once).

 

And I think there is some crockery and cutlery involved too.

Edited October 20, 2015 by David Mack

[Phil Ambrose]

Don't rubbish lunar illumination !! A guy I know was baffled by his kit reporting the production of electricity at night and it was indeed the illumination from the moon ! Apparently these days some panels have such good low light response that they will produce electricity at night - roll on advances in solar panels .

 

Nick

I have found this myself, not surprising really as Moonlight is simply reflected Sunlight. It has to be said that output is minimal to say the least but measurable.

Phil

[manxmike]

Since I live on the Isle of Man and my boat is in Cheshire it costs me well over £100 every time I visit the boat. As you can imagine this limits my visits to about one weekend a month.

From my point of view solar makes sense, even in the winter. A steady (small) trickle of charge keeping the batteries topped up means I don't need to run the engine as much when I am on board. A weekend is not really long enough to do much other than necessary maintenance and "firkling" so sitting in the Marina with the Lister chugging away doesn't make me the most popular person.

[MtB]

for a leisure boater like myself (currently) they are extremely useful whatever the season simply because it (almost) removes the need for a regular battery charging regime while the boat is not in use and negates the need for a mains hookup while idle in the marina.

 

More specifically, for a weekend boater like I used to be, the solar allowed me to leave the fridge ON (and therefore full of food) all week while I was away at work. Very handy not to have to take it all home on a Sunday night, then restock the next weekend.

[Naughty Cal]

 

More specifically, for a weekend boater like I used to be, the solar allowed me to leave the fridge ON (and therefore full of food) all week while I was away at work. Very handy not to have to take it all home on a Sunday night, then restock the next weekend.

We do this simply by plugging in

[peterboat]

i manage for most of year on solar i get a slight reading on very moonlit nights as well. my panels are glued down i suspect the metal roof that is painted cream acts as a heat soak in summer.

i know that pv panels that are water cooled are available as i have seen them, the water is used to heat water in the house/building they work well but are expensive.

[emlclcy]

i manage for most of year on solar i get a slight reading on very moonlit nights as well. my panels are glued down i suspect the metal roof that is painted cream acts as a heat soak in summer.

i know that pv panels that are water cooled are available as i have seen them, the water is used to heat water in the house/building they work well but are expensive.

just done a search for water cooled solar panels and found this

http://www.sciencedirect.com/science/article/pii/S2090447913000403

I think I'm on to something here... let canal water trickle over the front surface (panel at an angle) which will cool and clean the panel, maybe beads of water will act as magnifying lenses

looks like i'll have to wait until next year to prove this tho...

[PaulG]

Don't rubbish lunar illumination !! A guy I know was baffled by his kit reporting the production of electricity at night and it was indeed the illumination from the moon ! Apparently these days some panels have such good low light response that they will produce electricity at night - roll on advances in solar panels .

 

Nick

I think your friend was just baffled, full stop!

 

The maximum power available from sunlight is around 1120 watts per square meter.

 

The moon is about one million times dimmer than the sun, so the amount of energy reaching his panel is 0.00112 watts per square meter, assuming that the moon is directly overhead.

 

Take into account the energy conversion efficiency of the solar panel - 20% is probably generous - then you are left with 0.000224 watts per square meter.

 

At 12 volts, that represents a current of 0.000019 amps, or 0.019 milliamps per square meter of panel.

 

If your friend could measure that, I'm simply amazed!

[Paul C]

"Something for nothing" - its true that the running cost of solar power is pretty much £0 but the capital cost must also be considered. If you knew the power requirement over a period of time - sunshine (and moonshine) levels are fairly predictable long term - then you could calculate the worth of installing it. You'd also need to know the cost of producing electricity by other means, eg how much it costs to run your genny/engine; or if hook up, the rate you pay for this. I suspect that most people don't have an accurate idea of these costs, and a number of people don't know how much power they (will) use (in the future).

[MtB]

I think your friend was just baffled, full stop!

 

The maximum power available from sunlight is around 1120 watts per square meter.

 

The moon is about one million times dimmer than the sun, so the amount of energy reaching his panel is 0.00112 watts per square meter, assuming that the moon is directly overhead.

 

Take into account the energy conversion efficiency of the solar panel - 20% is probably generous - then you are left with 0.000224 watts per square meter.

 

At 12 volts, that represents a current of 0.000019 amps, or 0.019 milliamps per square meter of panel.

 

If your friend could measure that, I'm simply amazed!

 

 

That's about what I get on an overcast day!!!