Vertical solar panel

[Graham_Wright]

Great discussion. Very little reference to reflected power from the water. There was sufficient supporting opinion to encourage me to buy another panel for experimentation.
I'll report back.

 

[thinwater]

Great discussion. Very little reference to reflected power from the water. There was sufficient supporting opinion to encourage me to buy another panel for experimentation.
I'll report back.

Get a light meter (camera or perhaps your phone) and measure the mount of light coming up from under a shade (your hat will do) and then under the hard top or bimini. Yes, there is some reflected light, enough for a fair person to sunburn if they stay there long enough, but only about 10% of full sun on the average, depending on the sun angle and other factors. Of course, you meter will probably go off scale when you point it at the sun. An obvious hint. You can stare at the deck but you can't stare at the sun. Get a light reading off a sheet of paper in the sun and then a sheet of paper in the shade.

This is a faster, cheaper, more accurate expereiment than buying panels. Fewer variables.

A lot of what you see on You Tube is either purchase bias (you want to believe your purchase was smart) or click-bait. The vertical bifacial panel solar farm example is a different case that I believe is true. I'm guessing they stay cleaner in the desert (no rain). Totally different math. Of course, even in that case, it only works if the panel walls are far enough apart that they don't shade each other too much in the morning and evening (I'm guessing the very early AM and PM rays don't amount to much because of the increased depth of atmosphere--they don't feel like it and you can also look that up). OK if you have a lot of real estate, but not so much on a boat.

 

[onesea]

Great discussion. Very little reference to reflected power from the water. There was sufficient supporting opinion to encourage me to buy another panel for experimentation.
I'll report back.

Next time I am away from berth on appropriate heading and battery charge etc I will flick my l sunny side screen round and note the solar input change.
However on sunny days. It’s hard to monitor as the controller is doing it’s job stopping over charging of the batteries so throttling the solar input.

 

[thinwater]

^^ This is why reporting based on amps is very inaccurate. Too many variables.

• Temperature
• SOC
• Exact angle to sun
• Time of year
• Cloud cover and even haze
• Shading
• Cleanliness of panels
• Age of panels
• Size/type battery bank
• Wiring
• Charger, charge profile, and stage of program.

Way too many variables, other than very practical knowledge for the system operator. Even testing your own panels to determine loss in output over time requires detailed documentation and careful adjustment for the many factors. For example, you need to disconnected them and test them against a known, repeatable load, not your battery bank.

 

[vas]

late in the discussion, on each thread like that I like to point to this project:

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission

import your data, angles, sizes, position, whatnot and get monthly or annual production. It has been tested against solar farms here and it's v. accurate!
Make sure you get the data right and get realistic panel temps for hottish areas as it really messes production.

 

[B27]

If you want to evaluate a panel or a panel location/orientation, personally I find an unshaded, horizontal panel a good reference.
Unlike lightmeters etc, one silicon panel will have similar response to the next, when it comes to wavelengths of light and all that.

If you measure short circuit current, you only need one meter for your test panel and one meter for the reference and the effects of loading are set aside.
That way you can get some useful information about the relative merits of panel locations and check out a new panel, even in variable overcast conditions..

It depends what you want to know.

If you want to look at yield and avoid the variables introduced by batteries and charge controllers, then a cheap 'coulomb counter' or amp-hour meter can keep score of short circuit current over the day or week. You can relate short circuit current to max power current fairly accurately.
Alternatively you can use some sort of active load to run at the max power voltage, or try different algorithms to actively track max power.

FWIW, I think you will find the reflected light off the sea relatively rich in UV but not particularly powerful for PV cells.

 

[mattonthesea]

Get a light meter (camera or perhaps your phone) and measure the mount of light coming up from under a shade (your hat will do) and then under the hard top or bimini. Yes, there is some reflected light, enough for a fair person to sunburn if they stay there long enough, but only about 10% of full sun on the average, depending on the sun angle and other factors. Of course, you meter will probably go off scale when you point it at the sun. An obvious hint. You can stare at the deck but you can't stare at the sun. Get a light reading off a sheet of paper in the sun and then a sheet of paper in the shade.

This is a faster, cheaper, more accurate expereiment than buying panels. Fewer variables.

A lot of what you see on You Tube is either purchase bias (you want to believe your purchase was smart) or click-bait. The vertical bifacial panel solar farm example is a different case that I believe is true. I'm guessing they stay cleaner in the desert (no rain). Totally different math. Of course, even in that case, it only works if the panel walls are far enough apart that they don't shade each other too much in the morning and evening (I'm guessing the very early AM and PM rays don't amount to much because of the increased depth of atmosphere--they don't feel like it and you can also look that up). OK if you have a lot of real estate, but not so much on a boat.

Our flat roof panels are angled at 20 degrees to horizontal because any higher they will shade each other too much. That's from a national energy website but I can't remember if EU or Brit.

 

[thinwater]

...Unlike lightmeters etc, one silicon panel will have similar response to the next, when it comes to wavelengths of light and all that....

Light meters are solar cells. They make electricity and the meter measures the current. Of course, the cell type may be slightly different, but they are both measuring the same wavelengths. Visible light is 380 to 700 nm, and panels typically use a little of the very near IR. They do not use UV.


Reflection is relatively even across the spectrum and depends mostly on the angle (more reflection at low angles). Reflected light is not stronger or weaker in UV than sunlight, but it will generally be only about 10% of the intensity (very angle dependent).

reflection vs refraction

 

[AntarcticPilot]

I mount mine like dodgers on the guard rails. If you do the maths, there is a disadvantage at our latitude, but not a vast one.

 

[B27]

Light meters are solar cells. They make electricity and the meter measures the current. Of course, the cell type may be slightly different, but they are both measuring the same wavelengths. Visible light is 380 to 700 nm, and panels typically use a little of the very near IR. They do not use UV.

View attachment 180776
Reflection is relatively even across the spectrum and depends mostly on the angle (more reflection at low angles). Reflected light is not stronger or weaker in UV than sunlight, but it will generally be only about 10% of the intensity (very angle dependent).

reflection vs refraction

Lightmeters are solar cells, but filtered to give the desired response.
Reflection is not even across the spectrum, hence the sea can look blue....

The acid test is usually to make your experiment as real as possible.
If you want to know what a PV panel will do, using a similar PV panel in your experiment is rarely a fundamental mistake.

 

[B27]

I mount mine like dodgers on the guard rails. If you do the maths, there is a disadvantage at our latitude, but not a vast one.

The maths are one thing, but vertical panels may suffer when you're moored anywhere where you don't have a clear view to the horizon.
Most of the places I moor or anchor are in the lee of something to the west, that's why they are a sensible place to moor in the prevailing wind.
This tends to mean vertical panels get shaded from the evening sun.
OTOH, I use my small panel in Winter close to vertical, it gets a fair dose of whatever sun there is from the South in Winter, it has reasonable line of sight for the winter solar elevation.
If you're anchored, a mix of horizontal and vertical panels in several directions gives a good chance of getting some power most of the day regardless of which way the boat is facing.

When it comes to land based panels, the economics of it have changed due to the falling price of panels.
Many people are finding so E-facing panels and some W-facing works well in the context of energy tariffs that vary through the day.
Like many things, it's not pure science because politics and economics have an influence,
If you're allowed 4kW of export, then you can do that more hours a day with W&E panels.

How do you quantify the benefit from your system and what are your constraints in terms of cost, space to mount panels etc.?

 

[AntarcticPilot]

The maths are one thing, but vertical panels may suffer when you're moored anywhere where you don't have a clear view to the horizon.
Most of the places I moor or anchor are in the lee of something to the west, that's why they are a sensible place to moor in the prevailing wind.
This tends to mean vertical panels get shaded from the evening sun.
OTOH, I use my small panel in Winter close to vertical, it gets a fair dose of whatever sun there is from the South in Winter, it has reasonable line of sight for the winter solar elevation.
If you're anchored, a mix of horizontal and vertical panels in several directions gives a good chance of getting some power most of the day regardless of which way the boat is facing.

When it comes to land based panels, the economics of it have changed due to the falling price of panels.
Many people are finding so E-facing panels and some W-facing works well in the context of energy tariffs that vary through the day.
Like many things, it's not pure science because politics and economics have an influence,
If you're allowed 4kW of export, then you can do that more hours a day with W&E panels.

How do you quantify the benefit from your system and what are your constraints in terms of cost, space to mount panels etc.?

Well, I don't depend on them to run a vast amount of equipment, so my main concern is ensuring the batteries stay fully charged, which they do easily even in winter. But if your requirements are greater - for example, running a refrigerator at anchor - then of course factors such as you mention matter.

 

[thinwater]

Lightmeters are solar cells, but filtered to give the desired response.
Reflection is not even across the spectrum, hence the sea can look blue....

I think that is actually more because the sky can look blue. If you have a data source regarding wavelength vs. reflection from water I would love to see it. I looked and could not find it. Please post! I see no reason in the simple physics and reflections on flat water are typically relatively true to color. In any event, the effect is limited. The average intensity ratio by angle is easily calculated, though chop will have a significant effect. Also, the lower the sun angle the greater the atmospheric correction, depending on the amount of haze. A lot of the optimistic data on the internet is based on standard test conditions in the desert, not UK conditions of overcast and haze. The thicker the atmosphere (low angle) the greater the effect.

The acid test is usually to make your experiment as real as possible.
If you want to know what a PV panel will do, using a similar PV panel in your experiment is rarely a fundamental mistake.

I don't disagree with using a PV panel, but there is the expense and the difficulty in rigging up the load side. But if you have the panel, go for it.

 

[ghostlymoron2]

I'm very much a fit and forget type along with most live aboards, no time or inclination to adjust. Horizontal or near using semi flex panels are my favourite. They may not be at optimum elevation and suffer a degree of shading but provide trouble free power. If I had a larger yacht I'd probably use larger rigid panels.

 

[thinwater]

I just sat down with Excel and some tables for atmospheric absorption ... and I get that bifacial panels, at least at the one latitude and season I ran them (45N, spring/fall equinox) have no real advantage. An interesting exercise in trig. The problem is that they absorb most strongly in the morning, when the sun has to burn trough 50 miles of haze (low angle) and then not at all when the sun is overhead. The morning sun simply isn't strong enough to make up for the slight geometric advantage. This was not with clouds, just a typical clear day in a coastal area.

In the desert the math is different. A lower absorption factor makes the morning sun stronger. The desert warms up fast. I'm guessing most UK sailors have not even seen a desert, let alone hiked in one. They are great places for solar, in part because of the sun and in part because they pay higher rates (they are often remote), but it isn't part of a sailor's reality.

So what did I get (roughly--I need to refine the reflection and absorption factors and run some more cases)?

Type equivalent hours if straight at the sun
flat single 3.5
45 degree tilt south 4.0
45 degree tilt east 3.0
bifacial vertical N/S 4.0
bifacial vertical E/W 3.4

The E/W cases are because a boat will spin.
I assumed zero shading for the panels, other than what they cast themselves. This is particularly important for the vertical bifacial panels, because they need morning sun.

The results would be higher in the desert and in the summer. For example, flat panels are typically rated at 5 hours for design purposes in temperate latitudes. But they would all be higher.

Vertical bifacial panels have other advantages that would have serious merit in a farm:

• They stay clean
• Hail stones won't hit them
• Easier to mow etc.
• Easier to mount in a farm

But none of these matter to me on a boat. And there are disadvantages--I'll skip those. But it seems clear there are reasons that they won't take over all installations. On a boat, to me, the omnidirectional nature and simple mounting of flat wins hands down. Second place goes to panels you can tilt, if the bother seems worth it.

 

[onesea]

"Vertical bifacial panels have other advantages that would have serious merit in a farm:
They stay clean
Hail stones won't hit them
Easier to mow etc.
Easier to mount in a farm
But none of these matter to me on a boat. "

However if vertical is a practical mounting option, solar is cheap enough now a couple of vertical mitre panels might be a practicable solution.

It is for me, no solar arch and all electricity I need. With more discreet solar than some boats with solar arches.

 

[thinwater]

"Vertical bifacial panels have other advantages that would have serious merit in a farm:
They stay clean
Hail stones won't hit them
Easier to mow etc.
Easier to mount in a farm
But none of these matter to me on a boat. "

However if vertical is a practical mounting option, solar is cheap enough now a couple of vertical mitre panels might be a practicable solution.

It is for me, no solar arch and all electricity I need. With more discreet solar than some boats with solar arches.

• You must have a location with no shading on either side. That means not on the sides, only on the roof or foredeck, where the boom or jib are a problem. Possible on a davit arch.
• Vertical was only better than flat if you can anchor the boat north/south every time.
• Windage. With flat, practically zero. With vertical, very considerable, which means heeling, bracing, and slower sailing. Also higher center of gravity. Really, a non-starter all around.

So no, actually don't think this is at all practical on a boat. But a good thought experiment and it will have me thinking about my daughter's house.

Now, if you want to mount semi-flexible panels on the cabin sides (I would do that if there was good space, but generally there are windows) or rigid along the railings, they won't be super efficient, but amps are amps.

In my mind, any thing I have to align or mess with won't happen and the real world Ah will be less than good flat panels. Multihulls are a luxury this way. Yes, I will admit they have down sides, I don't want to start that fight on this thread. But solar space is an up-side.

 

[onesea]

• You must have a location with no shading on either side. That means not on the sides, only on the roof or foredeck, where the boom or jib are a problem. Possible on a davit arch.
• Vertical was only better than flat if you can anchor the boat north/south every time.
• Windage. With flat, practically zero. With vertical, very considerable, which means heeling, bracing, and slower sailing. Also higher center of gravity. Really, a non-starter all around.

So no, actually don't think this is at all practical on a boat.

What a load of... Boats are not solar farms (although some start to look like them). It depends on your boat and layout.

I can tell you they work very well, attached is today's production as well as the last /few days.

You can tell when I ran engine the voltage increased without solar watt increase.



I don't think I have tilted them in this period, the consumption is only a fridge and charging a phone. There is other consumption instruments, torches, Nav lights, tablets etc, that are not monitored by charge controller.

This summer I have not felt the need to plug in in over 2 months onboard.

That's 2 vertical 100w mounted on opposite sides of the boat in replacement of side screens with a little 30 watt horizontal panel that is often shaded.

After a couple of cloudy days at Anchourage, i tilt them just to top up. But if it's sunny they seem to do the job, without the ubiquitous solar arch.

Of course they could be more efficient, however they supply all the power I need that is enough for me.

Edit to add:
I did consider making them bifacial and doubling my theoretical power, how ever I just don't need it.

 

[thinwater]

I'm not sure which part was a load of BS. I think perhaps you skipped some prior posts. You have to read the whole thread; we don't restate everything in every post. I don't think anything I wrote was factually inaccurate if taken in the context of all of the other posts.

I was comparing vertical to horizontal panels. Nothing else. It had been suggested that vertical bifacial panels were the way to go, better than horizontal. This is simply is not so on a boat. But that doesn't mean vertical can't work. I even said that I would place panels on the cabin sides, for example, if that was the space I had. They all help. We all agree on that.

I could report my charging history as well. Without detailed documentation of all of the factors (post 24) it would mean nothing at all.

 

[onesea]

I recently visited son at his girlfriends house. The garden is modest and the roofs not ideally angled for panels.
He has used the vertical panel garden fence for attaching the panels and it is very successful. If you do the trig, there is not a huge disadvantage and the panels he has installed run the wholc house ( in "summer").
That arrangement started me thinking about boat arrangements. I currently have two panels one each on the pushpit rails. There is no ideal additional space. However, I could hang a couple on the guard rails. They would be near vertical and thus far from ideally angled. BUT, as those who have been burned by reflected reflected from the water will know, there is a sizeable insolation available.
Perhaps worth an experiment.

• I'm not sure which part was a load of BS. I think perhaps you skipped some prior posts. You have to read the whole thread; we don't restate everything in every post. I don't think anything I wrote was factually inaccurate if taken in the context of all of the other posts.

Reading the op's post above his experiment is can he add to his solar capacity by adding vertical panels the answer is yes.

It doesn't need detailed analysis, yes my figures scientifically mean nothing.

However it shows vertical mounted panels can produce significant amounts of electricity on a tilting moving boat that is not aligned north south etc. The shaded panel must do something as today I note I briefly generated 100w which is 100% of one not optimally aligned panel.

The lists of musts below are definitely desirable but certainly not a necessity.
My boat home mooring is near enough east west and if I am pointing at the sun both panels are in the shade.

The worst place for vertical solar arrangement is marinas or docks.

• I was comparing vertical to horizontal panels. Nothing else. It had been suggested that vertical bifacial panels were the way to go, better than horizontal. This is simply is not so on a boat. But that doesn't mean vertical can't work. I even said that I would place panels on the cabin sides, for example, if that was the space I had. They all help. We all agree on that.
  
  I could report my charging history as well. Without detailed documentation of all of the factors (post 24) it would mean nothing at all