Csail
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What is the optimum angle to position a solar panel (S Wales) and obviously facing south.
solar angle
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Gin
Well-Known Member
Since the sun appears to move across the sky it follows that for'optimum' performance your solar panel must track it-anything else is just a compromise
reeac
Well-Known Member
[ QUOTE ]
What is the optimum angle to position a solar panel (S Wales) and obviously facing south.
[/ QUOTE ]
The PBO article of October 2005 says best to mount at 20 degrees plus your latitude [ie. a total of 72 degrees for S. Wales] above the horizontal. It adds that you can gain up to 14 % in output cf. having the panel horizontal.
What is the optimum angle to position a solar panel (S Wales) and obviously facing south.
[/ QUOTE ]
The PBO article of October 2005 says best to mount at 20 degrees plus your latitude [ie. a total of 72 degrees for S. Wales] above the horizontal. It adds that you can gain up to 14 % in output cf. having the panel horizontal.
geoffatstanpit
Well-Known Member
But that will be offset by the 14% loss in effective area due to seagull cr*p.
geoffatstanpit
Well-Known Member
Oops! forget that - I didn't read the "cf." Mine faces into wind (quite often SW) at 20 degrees from the Horiz. Gives 15 volts when the sun's out even in Jan.
oldsaltoz
Well-Known Member
As long the angle is enough to allow water and some poo to be washed off does it matter?
demonboy
Well-Known Member
Some boats I've seen have solar panels mounted on ball and socket brackets. That way the panels can be moved at all angles to capture the sun, where ever it is in the sky. Anyone any comments/experience on this?
VicS
Well-Known Member
[ QUOTE ]
Anyone any comments/experience on this?
[/ QUOTE ] Ok for liveaboards but it gets expensive hiring a crew 7 days a week to adjust the panel every hour or so while you are away.
Anyone any comments/experience on this?
[/ QUOTE ] Ok for liveaboards but it gets expensive hiring a crew 7 days a week to adjust the panel every hour or so while you are away.
andy_wilson
Well-Known Member
Yup, facing South. 20 deg less than Latitude (so 30 - 35 deg) seems popular, to optimise output when the sun is highest and therefore passing through the least atmosphere. This angle will give almost maximum output for 2-3 hours either side of noon (on a sunny day). Mounting at latitude (say 50-55 depending where you are) will give maximum output possible at noon, but less overall.
10 degrees steeper will give greater output in the winter, when the sun doesn't reach so high in the sky, at the expense of peak summer output.
10 degrees steeper will give greater output in the winter, when the sun doesn't reach so high in the sky, at the expense of peak summer output.
demonboy
Well-Known Member
[ QUOTE ]
Ok for liveaboards but it gets expensive hiring a crew 7 days a week to adjust the panel every hour or so while you are away.
[/ QUOTE ]
I am a liveaboard!
Ok for liveaboards but it gets expensive hiring a crew 7 days a week to adjust the panel every hour or so while you are away.
[/ QUOTE ]
I am a liveaboard!
A
Anonymous
Guest
Very interesting problem for boats at anchor. I have done some calculations (they are quite easy, actually, and don't require more than what was O Level physics) and you find that if you incline the panel you will in all probability get less power from your array than if it was flat.
Tips:- Length of atmospheric path determines W/m2 because the energy is absorbed by the atmosphere. The sunshine must be resolved into components (like vectors) so that W=W1cos(Y) where Y is angle of incidence W= usable power at surface of PV in W/m2 and W1 = actual power from the sun perpendicular to the rays.
As you will see if you play with the angles (a fag packet and light bulb illustrate the point quite well) you are better off with a flat panel unless you are in a fixed location and even then you need to keep adjusting the angle as the seasons change. The point about seagull poo is very relevant, though we don't get much of a problem on our flat panels. On the other hand, we don't get many gulls in Almerimar, either /forums/images/graemlins/smile.gif
Tips:- Length of atmospheric path determines W/m2 because the energy is absorbed by the atmosphere. The sunshine must be resolved into components (like vectors) so that W=W1cos(Y) where Y is angle of incidence W= usable power at surface of PV in W/m2 and W1 = actual power from the sun perpendicular to the rays.
As you will see if you play with the angles (a fag packet and light bulb illustrate the point quite well) you are better off with a flat panel unless you are in a fixed location and even then you need to keep adjusting the angle as the seasons change. The point about seagull poo is very relevant, though we don't get much of a problem on our flat panels. On the other hand, we don't get many gulls in Almerimar, either /forums/images/graemlins/smile.gif
William_H
Well-Known Member
The whole question is resolved by fitting an ampmeter which will tell you the current going into the battery. (don't rely on open circuit voltage it is current that matters) (delete any regulator in circuit)
Surely it is not a question of distance through atmosphere but rather the area presented to the sun ie at 45degrees off optimum only the sun in effect sees only half the area.
For boats on swing moorings you face the panel in the most common drection in the middle of the day. Mine is mostly dictated by wind so this is possible but not so easy when yor boat diection is cictated by tide. olewill
Surely it is not a question of distance through atmosphere but rather the area presented to the sun ie at 45degrees off optimum only the sun in effect sees only half the area.
For boats on swing moorings you face the panel in the most common drection in the middle of the day. Mine is mostly dictated by wind so this is possible but not so easy when yor boat diection is cictated by tide. olewill
peteandthira
Well-Known Member
You guys need to look at MPPT controllers. These are equivalent to a third solar panel if you have two. They "work around" the massive loss of power from the typical 18V working voltage of most panels which, when dropped to 13.4V float charging voltage of most batteries, also drops the power output by 13.4/18 of their rated power.
Google for "MPPT" and check it out. Impressive.
Pops
Google for "MPPT" and check it out. Impressive.
Pops
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Anonymous
Guest
Yes, if you use dc-dc converter technology you can modify the load line and maximise power. I developed such a system and built a prototype with an early Mullard panel in 1978!
VicS
Well-Known Member
[ QUOTE ]
you face the panel in the most common drection in the middle of the day
[/ QUOTE ] I think the point is that although you acheive maximum instantaneous output when the sun is perpedicular to the panel averaged throught the day and the seasons you get more power if it is flat.
I am quite happy to let Lemain do the calculations to prove it though. It sounds more like A level maths than O level physics to me and that is something that I prefer to leave firmly in 1961.
you face the panel in the most common drection in the middle of the day
[/ QUOTE ] I think the point is that although you acheive maximum instantaneous output when the sun is perpedicular to the panel averaged throught the day and the seasons you get more power if it is flat.
I am quite happy to let Lemain do the calculations to prove it though. It sounds more like A level maths than O level physics to me and that is something that I prefer to leave firmly in 1961.
richardandtracy
Well-Known Member
The Centre for Alternative Technology (CAT) suggests that for peak annual hot water production on a fixed installation the panel faces SSW at 10 degrees less than latitude, with about a 10% reduction for installations up to 30degrees off this optimum if I remember correctly. (Reference 'Trapping the Sun' published by CAT).
Solar electricity panels are more sensitive to being off angle as there is a power density threshold below which no charging can take place, so it's more important to track the sun if possible. Peak power from a fixed solar cell installation would probably be closer to south & nearer to lattitude than for water to take maximum advantage of the peak input.
Regards
Richard.
Solar electricity panels are more sensitive to being off angle as there is a power density threshold below which no charging can take place, so it's more important to track the sun if possible. Peak power from a fixed solar cell installation would probably be closer to south & nearer to lattitude than for water to take maximum advantage of the peak input.
Regards
Richard.
