Biggest Solar Panels...

[CaptainRivet]

Originally Posted by Statistical

That is not what the spec is saying. If they get shaded the bypass diode will activate the voltage will be substantially lower.

And wherendo you see that in the specs?

Well my Victron MPPTs show different behavoiur of panels. voltage stays, current drops unless i shade a whole row on the long side of the panel. That hardly ever happens...

My point here is paralleling these panels deliever more then series connection. I tried it and have the victrons tracking it so the numbers don't lie. And they are mounted horizontally next to each other.
Also have each on their own controller gives 10% more output, they have backsides as well and work withbdiffusion light.

[Pete7]

Originally Posted by mark0978

You mount them based on manufacturer specs. These things are meant to take a lot of wind and have a rigid aluminum frame that only needs connecting in a few places to take really strong blows.

I have noticed that newer panels in the 300 - 400w range now have 30mm frames whilst they used to be 35mm, though 35mm panels are still available. Small change and perhaps 30mm is enough, or is it a cost cutting step?

Also is there a difference between mounting a super sized 500 - 600w panel on the roof of a house, to say mounting it on a yacht? After all, no one is making cheap large panels for yachts, they are all for commercial solar farms or domestic building installations. That is a huge piece of 3.2mm glass and is going to see both strong winds but also serious constant G forces as you bounce across the Gulf Stream in a North wind for example.

The work that Jedi and others have done has raised and questioned the status quo which is a good thing . It may be better to have more smaller panels if partial shading is likely to be encountered. Certainly worth taking time to consider all the options and even bi facials. Just wished they were readily available in the UK when I looked last year. Lots of adverts, but no stock.

Pete

[s/v Jedi]

Originally Posted by Pete7

I have noticed that newer panels in the 300 - 400w range now have 30mm frames whilst they used to be 35mm, though 35mm panels are still available. Small change and perhaps 30mm is enough, or is it a cost cutting step?

Also is there a difference between mounting a super sized 500 - 600w panel on the roof of a house, to say mounting it on a yacht? After all, no one is making cheap large panels for yachts, they are all for commercial solar farms or domestic building installations. That is a huge piece of 3.2mm glass and is going to see both strong winds but also serious constant G forces as you bounce across the Gulf Stream in a North wind for example.

The work that Jedi and others have done has raised and questioned the status quo which is a good thing . It may be better to have more smaller panels if partial shading is likely to be encountered. Certainly worth taking time to consider all the options and even bi facials. Just wished they were readily available in the UK when I looked last year. Lots of adverts, but no stock.

Pete

Mechanical strength is more important on boats than it is for residential installation. These are my considerations:

- 35mm frames on panels 2x1 meters or larger.

- if you cannot mount them using the manufacturer specified fastener holes, then you need to reinforce the frame to transfer loading to those fastener holes. Example: I will mount them on the short sides so I need a reinforcement on the long side, from the fastener hole to the corner of the short side.

- reinforcement is easy using 3/4” aluminium angle profile pop riveted inside the frame.

- the panels must not twist or bend. I wanted less than 5mm deflection for the new carbon fiber beams I’m gonna build soon.

The large panels (I’m looking at 440W panels) outperform smaller panels but of course you need a good location to install them. You can not install one sideways under the boom on a bimini. If that is your location, then use two panels, one on each side of the boom and give each panel a dedicated MPPT controller.

If you want independence from grid power and ICE power then you must build an arch on the stern. It will cost thousands of dollars but that’s the price for energy independence.

[CaptainRivet]

Originally Posted by s/v Jedi

Mechanical strength is more important on boats than it is for residential installation. These are my considerations:

- 35mm frames on panels 2x1 meters or larger.

- if you cannot mount them using the manufacturer specified fastener holes, then you need to reinforce the frame to transfer loading to those fastener holes. Example: I will mount them on the short sides so I need a reinforcement on the long side, from the fastener hole to the corner of the short side.

- reinforcement is easy using 3/4” aluminium angle profile pop riveted inside the frame.

- the panels must not twist or bend. I wanted less than 5mm deflection for the new carbon fiber beams I’m gonna build soon.

The large panels (I’m looking at 440W panels) outperform smaller panels but of course you need a good location to install them. You can not install one sideways under the boom on a bimini. If that is your location, then use two panels, one on each side of the boom and give each panel a dedicated MPPT controller.

If you want independence from grid power and ICE power then you must build an arch on the stern. It will cost thousands of dollars but that’s the price for energy independence.

I fully agree with that especially the davits. And mount bifacials on them, a more perfect use case for them doesn't exist and 20-25% additionally from the backside means installing 4 but get output of 5 panels plus extended production as the backside starts working when sun comes up or goes down as the water reflects the light to backside.

The overall thickness of the frame is only one part the thickness of the aluminium used another. I figured they reduced in heigth but the material gets thicker, the LG had 2mm 40mm thick L shaped frame, the Longli have a 4mm thick close square 30mmx15mm frame and a 2mm thick lip assume to enlarge the mounting surface.

In general high quality very known top tier brands have more robust frames then the cheap 2nd tier.
The manufacturer normally recommends to use them on a rail system where they are clamped down to the rail in various spots. The mounting holes are one indication, the plan how the rails must be placed and where they are clamped down is an alternative and often don't line up with the holes. The frames get more ridged to a) get the overall panel more ridged and b) so you can apply more clamping force thats needed to secure the bigger surface.
As an alternative mounting solution you can also get the aluminum rails, mount them on davits and clamp the panels down like on house roofs.
Done that with my longli panels as emergency solution as i couldn't get proper sized and fitting L profils in alu or stainless. Works surprisingly well, additionally to clamping i drilled the profils and also bolted them additionally to the frame where frame and mouting profile meet.

[noelex 77]

Originally Posted by eheffa

Thank you Noelex.

I've been considering your suggestion of going to the 100/30 model...Doing some back of the napkin math tells me that the 100/20 is just good enough for my current panels but if I ever wanted to upsize the PV panels, I would regret not going for the 100/30 controllers. The upgrade would cost another $200- CAD

Back to the marine store for an exchange, I think.


-e

Glad you found the advice helpful. It will be interesting to see the improvement in energy production. Sharing the results with the forum will be useful.

[noelex 77]

Originally Posted by s/v Jedi

If you want independence from grid power and ICE power then you must build an arch on the stern. It will cost thousands of dollars but that’s the price for energy independence.

The amount of shade free watts (or as shade free as possible on a sailboat) you can install is important. A stern arch is a great and relatively shade free location.

Some boatbuilders are installing panels in poor locations that will contribute little overall energy because of frequent shade. The number of watts fitted looks impressive in the sales brochure, but the real energy delivery can be disappointing especially if there is also the problem of little cooling air available to keep the panel temperatures reasonable.

The "quality" of the watts fitted is important. Rather than focusing just on the number of watts installed pay attention to both the "quality" and amount to gain a realistic picture of the likely energy generation.

[sailingharry]

Originally Posted by michaeld

Here is what works for us: three 175W panels in parallel. We get about 20A on a clear day.Attachment 277278

Curious if you have any experience on the impact of your backstay. I suspect you get a shadow at least half the time. I'm worse, as my backstay is split (but my panels are all behind the backstay, which helps some). Concern about backstay shadow is why I have 3 panels (instead of two larger ones) and 3 MPPT controllers. But it's a theoretical concern -- I have no real world input.

[eheffa]

Update:

I've had a few days at anchor with an opportunity to more carefully study the varying output of my panels with the plan to switch to 2 separate controllers while here.

The most production I see under ideal conditions with the heading and sun angle such that there is no shading of either panel, (2 x 275W wired in parallel) and at my latitude of 48°48'N in high summer is ~ 30 - 32 Amps. (My MPPT controller is rated for 45A so output is not likely to be limited by the controller capacity.)

It occurred to me that before tearing out my old installation and committing to 2 new separate controllers, I could test to see whether or not shading of one panel would degrade the total output of the system.

Switching to independent controllers would only make sense if:
Independent Port Panel Current (IPPI) + Independent STB Panel Current (ISPI) > Combined Panel Current with a shared controller (CPI).

Is IPPI + ISPI > CPI ?

Conversely, if IPPI + ISPI = CPI then there would be minimal value in switching to independent controllers.

I have breakers for each panel's output so can switch the panels off & on independently & compare to their individual output to when they are both on together.

When swinging to a heading where one panel is shaded & the other is in full sun in mid-morning, I found the following:



When independently feeding the controller with the non-shaded panel off, the shaded panel provided 1.5A. The non-shaded panel by itself with the shaded panel off, was producing 14A.

With both panel feeds on, in parallel, the total output was 15.5A which equals the sum of the 2 panels working independently. IOW, the combined output on a single controller was not degraded by the shading of one panel and the significant disparity in outputs between the 2 panels.

I repeated this later when there was a higher angle sun and with a 20A combined production, testing with each the panels separately with the controller dedicated to optimizing the production of each panel, the values were simply additive: 6A + 14A = 20A. (Note: I did give it some time to see whether the MPPT scanning would optimize the output.)

To make switching from one MPPT controller to 2 separate MPPT controllers worthwhile, one should see the combined joint output with a single controller to be less than the total of the two independent outputs due to the single MPPT controller not being able to optimize the disparate power curves. That doesn’t seem to be the case in my application; so, there is no value in changing the setup now.

It's possible that the Victron controllers would be better at finding the optimal power curve compared to my Morningstar controller, but that would be an expensive gamble to take the leap and try switching on pure hope...

So...the new unused and oh so compact and functional Bluetooth Victron, controllers go back.

If this was a new installation, it would make total sense to have each panel on its own controller but as a retrograde 'upgrade', the value doesn't seem to be there.

(In fact, looking at the bigger picture... I am seeing ~ 190 - 200 Ah daily solar production under sunny summer conditions. Improving that by 20% (unrealistic as that is without more panels or eliminating shading) would only gain another 40 Ah or so. With a 9.5 KW generator on board and 2 AC chargers, I can produce that much power in 15 minutes of charging so stepping back, it makes little sense to get too hung up on trying to extract an extra 10% solar production at a cost of several hundred dollars.)

My panels provide enough output so that there is no urgency to recharge in the morning and I can run the generator electively during daylight hours.

As much as the perfectionist in me hates to say it, the current setup is "good enough".


-Evan

[CaptainRivet]

Originally Posted by eheffa

Update:

I've had a few days at anchor with an opportunity to more carefully study the varying output of my panels with the plan to switch to 2 separate controllers while here.

The most production I see under ideal conditions with the heading and sun angle such that there is no shading of either panel, (2 x 275W wired in parallel) and at my latitude of 48°48'N in high summer is ~ 30 - 32 Amps. (My MPPT controller is rated for 45A so output is not likely to be limited by the controller capacity.)

It occurred to me that before tearing out my old installation and committing to 2 new separate controllers, I could test to see whether or not shading of one panel would degrade the total output of the system.

Switching to independent controllers would only make sense if:
Independent Port Panel Current (IPPI) + Independent STB Panel Current (ISPI) > Combined Panel Current with a shared controller (CPI).

Is IPPI + ISPI > CPI ?

Conversely, if IPPI + ISPI = CPI then there would be minimal value in switching to independent controllers.

I have breakers for each panel's output so can switch the panels off & on independently & compare to their individual output to when they are both on together.

When swinging to a heading where one panel is shaded & the other is in full sun in mid-morning, I found the following:



When independently feeding the controller with the non-shaded panel off, the shaded panel provided 1.5A. The non-shaded panel by itself with the shaded panel off, was producing 14A.

With both panel feeds on, in parallel, the total output was 15.5A which equals the sum of the 2 panels working independently. IOW, the combined output on a single controller was not degraded by the shading of one panel and the significant disparity in outputs between the 2 panels.

I repeated this later when there was a higher angle sun and with a 20A combined production, testing with each the panels separately with the controller dedicated to optimizing the production of each panel, the values were simply additive: 6A + 14A = 20A. (Note: I did give it some time to see whether the MPPT scanning would optimize the output.)

To make switching from one MPPT controller to 2 separate MPPT controllers worthwhile, one should see the combined joint output with a single controller to be less than the total of the two independent outputs due to the single MPPT controller not being able to optimize the disparate power curves. That doesn’t seem to be the case in my application; so, there is no value in changing the setup now.

It's possible that the Victron controllers would be better at finding the optimal power curve compared to my Morningstar controller, but that would be an expensive gamble to take the leap and try switching on pure hope...

So...the new unused and oh so compact and functional Bluetooth Victron, controllers go back.

If this was a new installation, it would make total sense to have each panel on its own controller but as a retrograde 'upgrade', the value doesn't seem to be there.

(In fact, looking at the bigger picture... I am seeing ~ 190 - 200 Ah daily solar production under sunny summer conditions. Improving that by 20% (unrealistic as that is without more panels or eliminating shading) would only gain another 40 Ah or so. With a 9.5 KW generator on board and 2 AC chargers, I can produce that much power in 15 minutes of charging so stepping back, it makes little sense to get too hung up on trying to extract an extra 10% solar production at a cost of several hundred dollars.)

My panels provide enough output so that there is no urgency to recharge in the morning and I can run the generator electively during daylight hours.

As much as the perfectionist in me hates to say it, the current setup is "good enough".


-Evan

Did you also measued the voltages not only the amps, so watts can be determined.

[eheffa]

@ CaptainRivet
PV voltage was pretty consistent at around 30-31 VDC.

My 660Ah house bank is a 12VDC system

Charging voltages at the time of these tests with the house bank down around 150 Ah , was around 12.5V

[CaptainRivet]

Exactly what i said as well like my panels behave
If you parallel 2 identical panel and one gets shaded you still add the current and voltage stays nearly the same and not like Jedi explained voltage drops too and thats why the output of the 2nd gets compromised 2 by the lower voltage.
If you would series connect them both would suffer from shading. Thats why you generally avoid series connecting panels on boats unless one panel doesn't have enough high voltage above battery voltages so MPPT starts working or very long cable runs cause too big of a voltage drop.

[s/v Jedi]

Originally Posted by CaptainRivet

Exactly what i said as well like my panels behave
If you parallel 2 identical panel and one gets shaded you still add the current and voltage stays nearly the same and not like Jedi explained voltage drops too and thats why the output of the 2nd gets compromised 2 by the lower voltage.
If you would series connect them both would suffer from shading. Thats why you generally avoid series connecting panels on boats unless one panel doesn't have enough high voltage above battery voltages so MPPT starts working or very long cable runs cause too big of a voltage drop.

How would shading of one panel have impact on the production of another, unshaded panel when it’s connected in series and not in parallel? That’s pure fiction.

Please post the production graphs so we can see the array output, not just readout currents.

Also, please connect in series and see how much you get. While in series it would be great to read voltage over each panel.

[eheffa]

Originally Posted by s/v Jedi

How would shading of one panel have impact on the production of another, unshaded panel when it’s connected in series and not in parallel? That’s pure fiction.

For my setup, previous testing comparing series to parallel, it showed reduced overall power production in series with one panel shaded compared to parallel. I did not take careful notes at the time but it would an interesting 3rd scenario re-test and to document.

Originally Posted by s/v Jedi

Please post the production graphs so we can see the array output, not just readout currents.

My controller doesn’t have a history function to retrieve graphs.

Originally Posted by s/v Jedi

Also, please connect in series and see how much you get. While in series it would be great to read voltage over each panel.

That, I’m willing to try again with more careful note taking.

[CaptainRivet]

Originally Posted by eheffa

For my setup, previous testing comparing series to parallel, it showed reduced overall power production in series with one panel shaded compared to parallel. I did not take careful notes at the time but it would an interesting 3rd scenario re-test and to document.


My controller doesn’t have a history function to retrieve graphs.


That, I’m willing to try again with more careful note taking.

I can confirm eheffas results.
I tried both with the LG conventional ones.
Paralell Volt stays same, current each panel add current what the produce, the shaded less the unshaded more.
Series, all panels dragged down to worst performing one.

Don't know whats wrong or you missed in your lab setup when testing that..

Bifacial you loose 10% when paralleling as you also have a backside and even both panels mounted horizontal side by side the backside gets different exposure. Having them each on its own mppt gained 10%. Didn't try series.
Bifacial are half cut cells.

[s/v Jedi]

I will be doing these tests as well with 4x 440W bifacial. If I can find them.