Solar panel test

Trotter said:
You’d be blocking windows and access. Plus an aesthetic eyesore.
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Correct, you wouldn't want to screw a panel across your door, would you?
Could you measure the surface area of one side of you van, minus the windows please? Then measure the surface area of your solar panels and tell me which has the largest surface area.
😉 Only joking.
 
xsilvergs said:
Correct, you wouldn't want to screw a panel across your door, would you?
Could you measure the surface area of one side of you van, minus the windows please? Then measure the surface area of your solar panels and tell me which has the largest surface area.
😉 Only joking.
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No!😬
 
If it's any help I have 330 watts mounted flat on the roof. MPPT controller. Since late October hardly any charging noted. Best seen in the height of summer 19 A x 14.2 V = 269.8 watts. This is at 57 27 North. The panels on my house are tilted at 50 degrees and even in mid winter have produced more than 1 kw from 4 kw panels. Now, mid feb, in really sunny conditions better than 3kw.
The angle of the panels to the sun seems to be critical, so obviously tilting and aimable panes would be best. I also have a 110 watt freestanding panel, this can be aimed exactly at the sun and linked to the van system via an Andersen plug. This can provide 3-4 Amps at 14V for a few hours in bright sunshine (Winter) It is however a pain to stow so lives on the roof rack and is only deployed in desperation.
Completely different story in southern Europe, where I get a consistent 10 A plus from the roof mounted panels.
Pity I can't go there and get the benefit of their higher sun as I usually would at this time of year.
 
xsilvergs said:
You're correct in what you say. I already have tilting panels and can see the benefits.

My point is that where I live in Dorset the suns max elevation is about 52 degrees (from memory). It rises from ~0* to 52* , if panels were mounted vertically there would be no need to make them tilting. The fact we persist in mounting them horizontally seems a bit pointless unless we intend to live near the equator.

Surely if you live at latitude 45 or further north, mounting them vertical should show an all year round benefit?
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Here you go (and this is a proper good idea as well as well as including a full 'how to')
 
On the shading point. Here's a pictorial example of how little of the surface needs to be shaded to make a very big difference in output.

This is on a 40w panel showing maximum short circuit current. First picture is unobscured current, second one is with a small area obscured and the third one shows how little of the panel was covered.

1613922238442.jpeg
1613922275482.jpeg

1613922313538.jpeg

Cheers

H
 
wildebus said:
Here you go (and this is a proper good idea as well as well as including a full 'how to')
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The windows in our van are tinted, perhaps one day someone will use the silicone of the solar panel as a tint on the window. Then we could all travel north of Latitude 45 and have our panels at the optimum angle and keep our tinted windows. Does one need tinted windows that far north?

Update:
Looks as though its been thought of https://www.technologyreview.com/2012/04/17/186721/tinted-windows-that-generate-electricity/
 
I am not sure of this but I did once query how the rating for solar panels was obtained, after all it has to be a constant to ensure and compare. I believe the rating given is the rating expected at the equator with the sun directly overhead. If that is the case then it explains al lot... Anyone confirm my understanding?
 
Winks said:
On the shading point. Here's a pictorial example of how little of the surface needs to be shaded to make a very big difference in output.

This is on a 40w panel showing maximum short circuit current. First picture is unobscured current, second one is with a small area obscured and the third one shows how little of the panel was covered.

View attachment 58512
View attachment 58513

View attachment 58514

Cheers

H
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As a matter of interest, how many diodes are in the little box on the back of the panel? I would assume two, one across each group of cells. So blanking of part of one group will half the output the panel can make.

So why is image 2 not half of the 2.79 volts from image 1?
 
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xsilvergs said:
So why is image 2 not half of the 2.79 volts from image 1?
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Well I recon, 2.79 / 2 = 1.395, the voltage developed across each cell group.

The working cell group has the diode from the shaded cell group in series with it. 1.395 - 1.13 = 0.265 volts.

0.265 volts is the volt drop of the schotty diode.

So panels in series are less affected by shading when you leave your DMM case (leaf, bird poo) on top of the panel.

These are just my thoughts while I've sat here watching my 50 W monocrystaline produce 0 watts.
 
xsilvergs said:
As a matter of interest, how many diodes are in the little box on the back of the panel? I would assume two, one across each group of cells. So blanking of part of one group will half the output the panel can make.

So why is image 2 not half of the 2.79 volts from image 1?
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I would assume you are right about the diodes but I'll never know because I donated the panel to a pal.

The readings are short circuit current. If you look at the meter in image three you can see it is set to A d.c. Still illustrates a point though.

Cheers

H
 
Winks said:
I would assume you are right about the diodes but I'll never know because I donated the panel to a pal.

The readings are short circuit current. If you look at the meter in image three you can see it is set to A d.c. Still illustrates a point though.

Cheers

H
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Ah, missed that, but I think the theory is right. I'll try it on a panel when I get a chance.
Thanks for pointing that out though.
 
Not wishing to take this to far off course, has anyone tried using blocking diodes, say when mixing panels of different makes/voltages.
 
Hulio said:
I was in the van today at lunch time was getting 5.9 amps from 2x100 watt panel's.

I had a problem with my panels last year were I was getting very little amps and traced it back to an on off switch that was in the solar set up.
I had to switch panels off before I went onto electric hook up, changed the switch and everything went back to normal
Hope this helps 🍌🍌🍌
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Mine are always connected, there should be no problem as they are fitted with a blocking diode, plus the regulaoter will not reverse flow current.
 
xsilvergs said:
Not wishing to take this to far off course, has anyone tried using blocking diodes, say when mixing panels of different makes/voltages.
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yes got 1 connected to solar , because that is what is advised by Marlec wind turbines to stop drain on batteries.
 
xsilvergs said:
How about this for an idea? Instead of going to the effort of making tilting panels, mount them vertical. Just fix them to the side of your van.

Your latitude is approximately the max elevation of the sun.

:cool::LOL:
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I wouldn’t be able to see out of the windows...😂
 
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