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

[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.

[Pete7]

I found rigging and the mast had only a marginal effect on a solar panel mounted on a stern arch. Sails however, made a bigger difference.

Shade isn't the only problem. Watch the output from something like a Victron MPPT even tied up in a marina and its constantly changing. Firstly even boat passing slowly creates a wave so the boat rocks and the angle to the sun changes. Seconding the MPPT is constantly hunting for the best charging point. Finally a cloud temporarily blocking the sun also makes a huge difference.

What do to about it? Nothing, fit as many panels as you can and don't worry, let the electronics sort it out whilst you do more important things like fishin'

[Grith]

Where there is a Will there is a way! We have fitted nearly 1000w of solar on a 28 foot trailerable semi liveaboard cruising yacht and I am about to use some removable foldable panels to increase this still further. 720w of rigid panels receive little shading whilst the rest suffer mast and sails shading but still give some limited output.
The over cabin top roof panel can be tilted when at anchor significantly increasing it’s output and a flexible one moves from the dodger to sitting on top of the stacked and packed main also upping it’s output dramatically.
The top of the foredeck carried dingy and the central at anchor fold out additional Bimini also look like likely places for portable foldable panel placement!

[thomm225]

I have a 27' boat totally powered by solar.

I have an Aft lazarette Locker where I keep one solar panel and the other is mounted on the side of the stern railing. I turn this one toward the Sun as it moves overhead.

Sometimes I use two smaller panels and face them toward the Sun directly. These I connect directly to the batteries.

Some folks have a stern railing mount for their 100 watt or so panel.

[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.

[sailorboy1]

I have 2 panels. Sometimes at anchor they shaded from the boom, so I move the boom. No big deal.

[Mike OReilly]

Shading is an issue for any solar panel setup, and sailboats are particularly challenging. And a small amount of shading can really affect the entire output of the panel. This is why I think it is best to go with smaller panels, run in parallel. If one goes out, it won’t drag down the the whole system.

Our boat is larger than the OPs, but has a relatively small area for solar. No space for davits, which is usually the best location for panels. So I’ve mounted four panels; two as a bimini and two forward of the dodger. All run fore-aft on either side of the boom, and all run in parallel.

With this 400 watts we can operate mostly independently of dino-charging. As long as we get a few hours of descent sun, we’re good.

[Adelie]

Shading a panel affects not just the output of that panel but also any panel
It shares a controller with.
This argues for small controllers for each panel rather than 1 big controller for all the panels.

This will cost a bit more but also put more power into the batteries.
It will provide redundancy, if a controller dies 2 panels can share.
If you want to limit the cost of the controllers, have panels on each side of the boat share.

[thomm225]

If you have good batteries and are not running tooo much electrical or electronics, the shading won't affect you much.

Since I got my two 6 volt 220 AH Golf Cart batteries which I have in series for 12 volts, my old panels can be shaded and I have no problem.

As soon as it is light, my panels will start charging the batteries.

My panels are a 10 year old 65 watt panel and a 6 year old 50 watt panel going through a Victron Smart Solar Bluetooth 75/15 MPPT Controller.

Both are connected to the controller.

I have autopilot, inverter, depth, VHF, computers, lights, and fans.

[Mike OReilly]

Originally Posted by Adelie

Shading a panel affects not just the output of that panel but also any panel
It shares a controller with.
This argues for small controllers for each panel rather than 1 big controller for all the panels.

This will cost a bit more but also put more power into the batteries.
It will provide redundancy, if a controller dies 2 panels can share.
If you want to limit the cost of the controllers, have panels on each side of the boat share.

How would I see this impact Adelie? I run my 400 watts in four separate panels (parallel) to one controller. I certainly see the impact as one, or more, panels get shaded, but I’ve not noticed any additional impact at the controller. But I’m not sure how I would…?

One controller for ever panel is certainly going to be optimal. It adds nice redundancy to the system, but it also adds a lot of cost and complexity to the system.

[Kropdad]

There two types, mono and poly. Poly being the older tech which becomes pretty crap with even a small shadow on them. monos are designed to work more effectively with shade as onĺy the shaded part stops working. I'm sure there is a better technical answer but that's the guts of it.

[skenn_ie]

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

[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.

[Adelie]

Originally Posted by Kropdad

There two types, mono and poly. Poly being the older tech which becomes pretty crap with even a small shadow on them. monos are designed to work more effectively with shade as onĺy the shaded part stops working. I'm sure there is a better technical answer but that's the guts of it.

Mono panels tend to have higher efficiencies and efficiency does not degrade as fast as panel temps increase.
Poly tend to be cheaper on a $/W basis.

There is some support for the position that Poly panels are somewhat more shade resistant.

https://solarmagazine.com/solar-pane...e%20conditions.

https://a1solarstore.com/blog/monocr...explained.html

[pbmaise]

Originally Posted by Adelie

Shading a panel affects not just the output of that panel but also any panel
It shares a controller with.
This argues for small controllers for each panel rather than 1 big controller for all the panels.

This will cost a bit more but also put more power into the batteries.
It will provide redundancy, if a controller dies 2 panels can share.
If you want to limit the cost of the controllers, have panels on each side of the boat share.

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?