Do all solar panels stop working if there is shade on any part of them?

[Grigory]

Panel consists from some chains of serially connected cells, chains are connected parallely.
If one or more cells are in a dense shadow, their resistance will be very high. This case all chain with this cell can't produce current, will not work. To avoid this effect, a shunt diode is placed with each cell, through which the current will flow around the "dark" cell. Chain voltage will drop, but current will flow.
Maybe not all manufacturers do this.

[wiekeith]

Originally Posted by skenn_ie

A series-wired panel will output the current of the weakest cell.

What do you mean by weakest?

[skenn_ie]

DC or AC doesn't make any difference. It is the voltage that makes the difference in transmission efficiency.

Panels wired in parallel provide the power of THEIR weakest cell, almost independent of the other panels. MPPT doesn't vary much with incident solar power, but available current at that voltage does.

Multiple converters will get a bit confused on the battery voltage. Each one takes a reading based on the program position in their pulse-charging cycle. They are almost all controlled by a microprocessor.

[Nicholson58]

Yes, partial shade drops output. Panels should always have multiple circuits with diode separation. This minimizes the loss to only the shaded circuit(s). Swinging on anchor we see vast changes in output of the MPPT and yes, a shroud is detectable.

Generally, I figure the need and double that for the nominal solar capacity, minimum. One of our cruisers cemented high efficiency flex panels to his deck with diode isolation.

[skenn_ie]

Originally Posted by wiekeith

What do you mean by weakest?

The one that is getting least light.

[Slovak]

Take a look at https://www.bougerv.com/pages/boat-solar-solution which have a different configuration / system to continue working while partially shaded.

Sailing Fair Isle put them on

https://www.youtube.com/watch?v=SUGtWzsVXdE

[MJH]

Originally Posted by OldGaffer1959

I've long carried a small solar panel on camping trips and this is the case with it and seems to be the case for other solar panels where this issue is addressed - in most cases, it isn't mentioned.

Bought a 25 foot sailboat recently and considering solar charging.

But except when at the dock (where you don't need it!) or anchored with a shore line or 2 anchors at opposite ends of the boat - the boat is always moving and there is no place to put solar panels where they won't be frequently going into shade from masts, sails and rigging.

How do sail boat owners deal with this? Is multiple small solar panels a solution?

Edit: After posting this, the forum found similar threads that deal with this issue. If this topic is of interest to you, go here: https://www.cruisersforum.com/forums...ons-90530.html

Occurs to me now that the best place for a large single solar panel will be on the dinghy I am towing.

I believe the practical answer to your question is to minimize your electrical needs and then install as much solar as you can on your boat. I have done so and with 4x140 (560W) panels on my dodger and stern arch they suffice, one or more are always getting sun. On my round trip to Hawaii I never had to start the diesel to charge my two 8D Gel batteries.

[Dirk01]

Originally Posted by Chotu

Answering the question, no. Not all panels stop producing when shaded.

Some manufacturers make solar panels specifically so that they can be shaded and still have pretty good output. You will have to Google to find those manufacturers I don’t know them off the top of my head but they are on my RV. The output is less overall, but the panels capable of putting out power when half of it is in the shade.

Or look here:

https://ae-solar.com/products-list/
and choose HSF

IMO paralleling the panels is a good advice.
If you need the voltage (i.e. for a 48V LFP system which can savely run an EP system), you mostly have to put in serial. But if ever possible, put one in parrallel to each of the serial connected panels but mounted on the other side of the boat. This might result in a not maximized but optimized output while you're fishing or diving or doing other most important things ;-)

Let me know your results.

Cheers
Dirk

Sorry for my bad accent - my native language is German.
Hopefully you can imagine or at least guess what I mean.

[Dirk01]

Originally Posted by pbmaise

I also endorse this route. I had three individual controllers for my three 300 watt panels. The price of the controllers were really cheap. Only about $5 USD including shipping. I bought them on something called Lazada in the Philippines which is kind of like Alibaba. The downside is running the wire. I used rather thick aluminum wire to each of the panels down to the controllers mounted in the engine bay and then fed them to the electrical panel.

https://www.lazada.com.ph/products/o...90195158.html?

PWM Solar Charge Controller

PWM is crap! MPPT is the way to go. If you need or seek for every bit of juice - just forget PWM!

The above advice is a cheap advice. Do you want to buy cheap and make it right later? Or do you want to do it right right away?

Just my 2 cents
Cheers
Dirk

[Dirk01]

Originally Posted by tweekes

I understand that panels with a dc to ac converter built in are superior in shade conditions. Also, ac will not require as heavy a wire as dc. Don't know any more details.

Sorry, but your understanding is wrong.
A DC to AC converter is just (in best case) a MPPT-controller and an ac-converter in series. This has nothing to do with the solar panel itself.

There are monos and polys but important is how they are interconnected and how much reserve cells are built in. Nothing else.

What for and how do you wanna use your ac power? Your on a boat, not at home!

Cheers
Dirk

I'm sorry but I'm a little bit annoyed by some pointless thoughts being thrown into the discussion. The OP asked a serious question and rightly expects informed answers. He doesn't expect guesswork or things you don't know about but have heard somewhere.

[FlyingScot]

Originally Posted by OldGaffer1959

I've long carried a small solar panel on camping trips and this is the case with it and seems to be the case for other solar panels where this issue is addressed - in most cases, it isn't mentioned.

Bought a 25 foot sailboat recently and considering solar charging.

But except when at the dock (where you don't need it!) or anchored with a shore line or 2 anchors at opposite ends of the boat - the boat is always moving and there is no place to put solar panels where they won't be frequently going into shade from masts, sails and rigging.

How do sail boat owners deal with this? Is multiple small solar panels a solution?

Edit: After posting this, the forum found similar threads that deal with this issue. If this topic is of interest to you, go here: https://www.cruisersforum.com/forums...ons-90530.html

Occurs to me now that the best place for a large single solar panel will be on the dinghy I am towing.

I'm sure you can find many youtube videos demonstrating how shading reduces output. Yes, quality of panel, number of diodes in the panel make a big difference. Also soft vs. hard shading.

Best bet is to put one quality MPPT per panel to maximize harvest and simplify wiring. There are other benefits and drawbacks, but trust me, do it this way. Put up as much as you can afford. Silent renewable power is amazing to have. Also buy quality panels.

[The Sun King]

A string of polycrystalline cells in a panel will stop working if one is shaded. Larger poly and mono panels like you see on home typically have 3 strings in the one panel, lessening a total loss of power. If you have, say, 3 panels in a string and one loses sun, bypass diodes in the shady panel let the power of the other sunny panels come through.


Amorphous panels, the dark gray ones with long lines in the active area instead of blue squares, only lose power from the shaded area and do much better in mixed light, such as on a sailboat. However, they are larger for the amount of power you get from them.


If you run strings of panels, it might work best for you to limit each string to one side or the other. Forget trying to angle them into the sun. Go flat.

[djdeakyne]

I got to this thread because another post asked about shading and after 6 pages of irrelevant divergent debate about wire size, the question was never answered. This thread seems much more appropriate and my question to you all is why is there no mention of using Solar Optimizers https://www.solaredge.com/en/product...wer-optimizers on our boats? These devices are widely available and used in home solar installations. They keep dark current from shaded panels from kicking off an entire string of series wired panels which is of course a big beef of us cruisers and this thread. While I'm at it, these Economizers have communication capability and it would be cool to know the actual wattage output of every individual panel on your boat. Before I spend $50/panel for these has anybody used them?