Portable (light) solar panels? - Page 2 - ClubTread Community

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post #16 of (permalink) Old 07-11-2012, 08:37 AM
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Quote:
quote:I personally looked into it and was very shocked to learn all the solar panel companies output numbers are very optimistic to say the least.
Will have to dig up the numbers and specs but the output numbers these companies list are for direct sunlight at the equator. Once you start moving away from the equator the panel efficiency drops. As well time of year, weather conditions, etc etc.. And another factor was the panel being directly pointed at the sun.
I have a solar panel setup for my home where I monitor power production on a daily basis. What I have found that there are several main factors that determine optimum power output from the panels, assuming of course there is no cloud cover in the sky.

One is time of day. The output will be highest in a 4 to 8 hour span centered around high noon when the sun is at it's highest, and the panels will put out the most when the sun is highest in the sky.

Another thing that affects the output significantly is the temperature of the panels themselves. In summer, when it's warm, I rarely get the rated power capacity of the panels. In winter, when the panels are very cold (ie -10 to -45c) I sometimes get well over the rated capacity, even though the sun is much lower in the sky, than in summer. There are a couple of factors that offset the temperature of the panels, such as the much clearer skies in winter (less haze) and perhaps some increased light due to the snow that may reflect a bit of extra light into the panels. But the main effect is temperature.

The panel ratings are based on 1 kw of energy from the sun per square meter and at a panel temperature of 25 C. Panel temperatures in summer can go to in excess of 50C or even 75C. Panel efficiency drops by .25% for thin film and by .5% for crystalline cells per 1 C rise in temperature.

The tilt of the panels to the sun does not have too much effect on performance unless it's significantly off. That is why many install panels on a roof at a fixed angle (usually close to the latitude in degrees from horizontal).

Small areas of shade on the panel can also have a huge effect, but has not been a factor with my system.
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post #17 of (permalink) Old 07-11-2012, 09:10 AM Thread Starter
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Really interesting info. Thanks everybody.
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post #18 of (permalink) Old 07-11-2012, 12:30 PM
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great info pathfinder,
A number of the characteristics like angle, temperature sun strength vary a great deal depending on the companies brand of panel.

Would be nice to see someone that has done a real life comparison on some of these portable units. But it would be a expensive and difficult job having to compare all the units at the exact same time. To guarantee they all had the same sunlight



Quote:
quote:Originally posted by path finder


I have a solar panel setup for my home where I monitor power production on a daily basis. What I have found that there are several main factors that determine optimum power output from the panels, assuming of course there is no cloud cover in the sky.

One is time of day. The output will be highest in a 4 to 8 hour span centered around high noon when the sun is at it's highest, and the panels will put out the most when the sun is highest in the sky.

Another thing that affects the output significantly is the temperature of the panels themselves. In summer, when it's warm, I rarely get the rated power capacity of the panels. In winter, when the panels are very cold (ie -10 to -45c) I sometimes get well over the rated capacity, even though the sun is much lower in the sky, than in summer. There are a couple of factors that offset the temperature of the panels, such as the much clearer skies in winter (less haze) and perhaps some increased light due to the snow that may reflect a bit of extra light into the panels. But the main effect is temperature.

The panel ratings are based on 1 kw of energy from the sun per square meter and at a panel temperature of 25 C. Panel temperatures in summer can go to in excess of 50C or even 75C. Panel efficiency drops by .25% for thin film and by .5% for crystalline cells per 1 C rise in temperature.

The tilt of the panels to the sun does not have too much effect on performance unless it's significantly off. That is why many install panels on a roof at a fixed angle (usually close to the latitude in degrees from horizontal).

Small areas of shade on the panel can also have a huge effect, but has not been a factor with my system.
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post #19 of (permalink) Old 07-11-2012, 01:47 PM
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Quote:
quote:Originally posted by jd22

d5100
I was going to recommend a battery grip and superlight AA Lithium batteries but Nikon doesn't make AA battery grips for the D5100. Should have bought a Canon []. Yeah, I went there. I guess learning to choose Canon over Nikon is something that comes with age and experience Jon

Bazinga!

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post #20 of (permalink) Old 07-11-2012, 03:28 PM Thread Starter
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Quote:
quote:Originally posted by leimrod

Quote:
quote:Originally posted by jd22

d5100
I was going to recommend a battery grip and superlight AA Lithium batteries but Nikon doesn't make AA battery grips for the D5100. Should have bought a Canon []. Yeah, I went there. I guess learning to choose Canon over Nikon is something that comes with age and experience Jon

Bazinga!

Lol, damn you.

In any case, I have seen some third party AA battery grips for the d5100, or the d3100 with a slight filing down of a plastic nub fits the d5100. However, I may just have to curtail my star trail shots for the summer to < 1 hour. Sad sad.
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post #21 of (permalink) Old 07-11-2012, 07:52 PM
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My Sony DSLR batteries weigh 78gr each and are good for well over 700 shots. OEM 1650 mAh batteries are $99.00 but I get 2000's off ebay for 15.00 each with shipping included and are as good as the OEM's. I carry 5 or 6 extra's on a week long trip and find that more than adequate.
Sony DSLR's have battery power displayed to the exact percentage point of power that's left.
Boo-yeah!
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post #22 of (permalink) Old 07-11-2012, 11:20 PM
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Here is something that may be good in the bush, perhaps other makes/models are better...
http://www.k-tor.com/hand-crank-generator/

A hand crank generator... Rain or Shine, Day or Night, charge by turning it around. Unsure how many times you need to crank it to charge an iphone , interesting concept and likely great for emergency situations.

Something like this may be more beneficial if it doesn't tire you out.

Video in Action:
http://www.youtube.com/watch?v=zr-qX...layer_embedded



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post #23 of (permalink) Old 07-12-2012, 11:39 AM Thread Starter
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Quote:
quote:Originally posted by BillyGoat

My Sony DSLR batteries weigh 78gr each and are good for well over 700 shots. OEM 1650 mAh batteries are $99.00 but I get 2000's off ebay for 15.00 each with shipping included and are as good as the OEM's. I carry 5 or 6 extra's on a week long trip and find that more than adequate.
Sony DSLR's have battery power displayed to the exact percentage point of power that's left.
Boo-yeah!
I'm sort of de-railing this thread, apologies in advance. Initial research I've done was hard to turn up an aftermarket battery for the d5100, as nikon puts some sort of chip in their name brand batteries, and then has the camera do a handshake when a new battery is inserted. Aftermarket batteries get the message 'this battery may not be used with this camera'.

Pretty lame of Nikon, wish I had known that when I purchased.

In any case, does anyone know of a cheaper battery than the en-el14 that suffices?
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post #24 of (permalink) Old 07-12-2012, 12:10 PM
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As long as you have a genuine battery in the camera you can use aftermarket batteries in the grip.
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post #25 of (permalink) Old 07-12-2012, 12:22 PM Thread Starter
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Quote:
quote:Originally posted by cutthroat22

As long as you have a genuine battery in the camera you can use aftermarket batteries in the grip.
I know, but I'm looking for a way of using solely aftermarket battery (s).
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