Solar The Solar Panel Thread

Drover

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What's LRPS got to do with solar panels:
http://rps.org/distinctions/lrps
cheers
Mike
What the heck is that site, you need to get away from your computer and get outside a bit more ...................... a proper LRPS (note capital letters) is need for those typical 5 days of cloud Victorian days....... Possibly a Jeep Thing
 

Crusty181

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Feb 7, 2010
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Thanks @mikerezny makes sense. Although i thought the sub-panels were wired in parallel? Could be wrong.

@Crusty181 could you use a slightly higher aluminum bracket where the existing panel was, i custom one that bolts to existing one, ally strip. Bit more work with 2 lots of bolts but might give you the clearance over jbox.
I looked at that, i can wrangle a slither of clearance doing nothing; maybe your idea to get another few mm. I have the cabling running thru suspended conduit between the panels to also take into account
 

Boots in Action

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Mar 13, 2017
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Looking good.

See what you mean about average junction box and no cable gland, they spared no expense.

Sounds like you already know that you only have to shade a single cell in a panel (if it has 36 cells) and the panel output pretty much goes to 0W. Bugger of a thing.
Hi @Clewsy , further to your query regarding the shading of cells in a solar panel, I did comprehensive tests at home here in sunny Brisbane today. I have 3 different folding panels bought at different times. The first one is a 180 W folding panel with 72 groups of solar cells - 6 horizontal and 12 vertical in EACH portion. It has only two wires coming out of back of panel to connection box. OCV was 20.8 volts with both halves connected in parallel.. The next panel 200 W folding has 16 groups of solar cells - 4 horizontal and 4 vertical. It has 3 wires coming out the back and I have 2 Schottky diodes across both outputs. The output voltage of each sub panel was 9.0 volts, and connected in series provides 18 volts (OCV) at the terminals . The other half of this folding panel is the same and connected in parallel , so still only 18.0 volts OCV.
The last panel is 200 W with 32 groups of solar cells (4 horizontal and 8 vertical) with the same diodes and connections. OCV for each sub panel was 9.4 volts and when connected in series produced 18.8 volts OCV. The other half of the folding panel is connected in parallel with this sub panel giving me 18.8 volts OCV.
Just giving you some feed back on how heat affects panel voltage as you mentioned, the first panel was dropping very slowly as it heated up after about 15 minutes in the sun. The second panel was poor, dropping quickly from just over 18.0 volts to 17.8 volts in a few minutes. The last and more recent panel started at 18.8 volts and was fairly steady at this voltage even after 15 minutes in the warm sun. So yes, some panels do not do so well when they get hot - poor coefficient of heat resistance in solar cells.
As far as shading is concerned, the first panel would shut down if even partly shaded as only one panel in operation - no sub panels. The Schottky diode would however provide a path around the shaded panel for current generated by other panel/s in a series string. The last two folding panels each contain two sub panels with bypass diodes connected across output terminals. When I covered one half( vertically), the voltage in the unshaded sub panel remained at 9.0 or 9.4 volts, but the shaded panel voltage dropped to less than 6.0 volts in each case. However, the total of both sub panels was still around the 15.0 volt mark as they are connected in series. Even when I had shaded one complete panel (of the two folding panels) and half of the remaining one (which was connected in series) , a voltage of around 15.0 volts was still showing. I was not able to measure current as I had no connection to a controller or any load. However, I would think that the current output would then be only a quarter of total possible panel rating, but it would still be generating some power even at a lower voltage if bypass diodes are functioning properly.
I hope this helps one come to grips with these issues. It all depends on how the panel is set up (with or without sub panels) and the number of output leads coming out from the back of the panel/s.And the importance of bypass diodes cannot be underestimated!!
 
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Apr 17, 2017
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Thanks @Boots in Action that's some great testing you've done there with different panels, well done.

I agree well worth testing to know the type of panel you have and how it's wired and if you have diodes or not can make a big difference if you can run your coffee machine in the morning or not.
 

Boots in Action

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Has anyone tried these flexible panels?

https://www.sunyee.com.au/collectio...ar-panel-generator-caravan-camping-power-mono

I wonder what they mean by “Do not wire the flexible solar panel in parallel or in series to avoid damage or shortened lifespan.”

Not too sure about that @RickB . Probably because they may not have any bypass diodes across the output terminals (under the plastic connector??) and remember, there is no solar controller included with these panels if the advertisement is accurate. There has been a lot of feedback on these type of panels in earlier posts and generally, they have not been good. Shortness of life and burn out in panels (probably caused by some part of panel being shaded and not bypassed??) and heat dissipation is vital. Just ask @Moto Mech as he has had lots of (BAD) experiences with flexible solar panels. Maybe they have been improved, but I like the glass panels even though they are heavier.
 
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Boots in Action

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There's a good example of why some people should restrict their travel videos to opinions about the beach views

Could not agree with you more @Crusty181 !! The panels they were using obviously did not have any bypass diodes to allow current from good panel to bypass the shaded one. And all the talk was about perfect conditions for solar generation is misleading. This rarely happens to most of us as generally there are a few clouds or less light on panels during various times of the day. And they are way out on the cost of MPPT controllers. Yes, you can get a PWM type for around $20.00 for 10A controller, although the PWM Topray solar controller 12V 30A as fitted into a lot of Jayco vans costs about $85.00 and does not provide much information for owners - just battery voltage, amps in and (if connected properly) amps out. You can get a GENUINE MPPT controller for around (or under as I did!) for $150.00 which will be not only be much more efficient but supply you with heaps of information as well, for just a few dollars more!! Where they got a figure of $700.00 , I do not know although they were charging a Lithium battery. Also, they must not be able to calculate properly as far as voltage, amps and watts if you watch the attached. Yes, it is all theoretical, but much more likely than what they were spruiking.

 
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Crusty181

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Feb 7, 2010
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Has anyone tried these flexible panels?

https://www.sunyee.com.au/collectio...ar-panel-generator-caravan-camping-power-mono

I wonder what they mean by “Do not wire the flexible solar panel in parallel or in series to avoid damage or shortened lifespan.”
I bought the Sunyee fixed panels based purely on a review of the Sunyee flexi's. Not sure about connecting them, flexi's of no interest to me, but the Sunyee flexi in the review performed very very well and outperformed a very expensive iTech flexi panel. My prelim tests of the Sunyee fixed panels was promising enough
 

Crusty181

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Feb 7, 2010
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Could not agree with you more @Crusty181 !! The panels they were using obviously did not have any bypass diodes to allow current from good panel to bypass the shaded one. And all the talk was about perfect conditions for solar generation is misleading. This rarely happens to most of us as generally there are a few clouds or less light on panels during various times of the day. And they are way out on the cost of MPPT controllers. Yes, you can get a PWM type for around $20.00 for 10A controller, although the PWM Topray solar controller 12V 30A as fitted into a lot of Jayco vans costs about $85.00 and does not provide much information for owners - just battery voltage, amps in and (if connected properly) amps out. You can get a GENUINE MPPT controller for around (or under as I did!) for $150.00 which will be not only be much more efficient but supply you with heaps of information as well, for just a few dollars more!! Where they got a figure of $700.00 , I do not know although they were charging a Lithium battery. Also, they must not be able to calculate properly as far as voltage, amps and watts if you watch the attached. Yes, it is all theoretical, but much more likely than what they were spruiking.

The distrubing thing about that video for me, aside from having not even a basic understanding of what was going on, was the "boys from Enerdrive are here again". Enerdrive sell solar equip and are self-claimed experts of all things solar, and peddle some very very expensive equipment, yet Dave the Enerdrive was holding the camera, filming the questionable info and silently went along with it
 
Apr 17, 2017
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Yes some of the info is incorect but some is. The ratio of mppt is always going to be more (2 -3 times) than pwm. Difference is where you shop, Myers or Shiploads.

Yes they should have said panels don't have diodes and shown what happens with panels with diodes

And they should have done some tests to show figures on mppt vs pwm, in cold weather mppt better by 20 -30%

In hot weather mppt better by 10 - 20%

And your loads versus how much solar you have, if your batteries are always 80% soc or higher then there is no efficiency difference as both mppt & pwm are in absorption mode which is constant voltage at that point and solar is mainly wasted then.

Come to think of it would be hard to put all that in a video and keep it short.

You could show angle of the sun differences in output, differences in temp to output, dirt on the panels, small wired versus big wires, good and bad connections.

Ahh too much for an intro video.
 

Drover

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My neighbour lashed out and bought some house panels yesterday, $40 each 2 yrs old, someone did a complete upgrade on their house or something, he reckons they test okay, I might borrow one off him be handy....

As for the vid, there are so many variables with testing them in real time, one little thing will effect the data, I just look at them out of boredom as they are usually pushing a product or ego.
 

Boots in Action

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I bought the Sunyee fixed panels based purely on a review of the Sunyee flexi's. Not sure about connecting them, flexi's of no interest to me, but the Sunyee flexi in the review performed very very well and outperformed a very expensive iTech flexi panel. My prelim tests of the Sunyee fixed panels was promising enough
@Crusty181 , Sunyee is a very good and reputable brand and you should be happy with those fixed panels. You could not compare them with flexi panels which , although the same company, have an entirely different construction and potential problems. IMHO.
 
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Boots in Action

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Mar 13, 2017
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Ferny Grove, Queensland
Yes some of the info is incorect but some is. The ratio of mppt is always going to be more (2 -3 times) than pwm. Difference is where you shop, Myers or Shiploads.

Yes they should have said panels don't have diodes and shown what happens with panels with diodes

And they should have done some tests to show figures on mppt vs pwm, in cold weather mppt better by 20 -30%

In hot weather mppt better by 10 - 20%

And your loads versus how much solar you have, if your batteries are always 80% soc or higher then there is no efficiency difference as both mppt & pwm are in absorption mode which is constant voltage at that point and solar is mainly wasted then.

Come to think of it would be hard to put all that in a video and keep it short.

You could show angle of the sun differences in output, differences in temp to output, dirt on the panels, small wired versus big wires, good and bad connections.

Ahh too much for an intro video.
I agree whole-heartily on what you said @Clewsy, especially your last sentence regarding differences. The lower the voltage in your batteries, the better the MPPT controller is in restoring power quickly. But isn't that what you want?? If conditions were the same all the time, then there would not be such a need as battery/ies voltage would not vary much UNLESS your were dragging out mega amps at various times. In those cases, a PWM controller would suffice. But get a few days of cloudy and misty weather, (and you don't know how long that will last!!) and you need the accelerated charging that a MPPT controller can provide. And in varying conditions of cloud cover and sunshine, you get more amps in every time regardless how short sunny conditions last.
But as explained, it was a SIMPLE explanation and comparison.