Bimini and solar panel sketches

[s/v Jedi]

I don't know your panels but am pretty sure they will have plenty bypass diodes. You should have documentation with it that shows this.

The Outback controllers are the ones to beat and thus pricey, but they can take 6x 12V panels in series.

I have a 12V disconnect switch both on the controller input and the output (I have the Outback 60).

Originally Posted by Utahsailor

s/v Jedi and Geopower: I saw the post about serial vs parallel in the reading binge before designing the first layout and then couldn't re-find it. All in series to a big controller would be ideal in terms of reducing the wire size and number of wires. Here is showing my ignorance- do I need to add bypass diodes for each panel or are they within the Kyocera panels? There is a voltage drop through diodes, so they do have a performance effect too. It would be easy to add a panel on the underside of the dodger to have a switch for each panel and to gang the wires for the serial run to the controller. Thanks for the suggestion.

[Utahsailor]

After receiving several excellent revisions, I submit Rev 2 of my solar panel plan. The main change is to gang panels in parallel with a switch box mounted on the bottom of the Bimini that will gang the conductors as well as allowing any of the panels to be disconnected. The two Morningstar 45 MPPT controllers and Trimetric data logger are replaced with a single Outback Flexmax 80 MPPT controller (the 60 model has a recommended 750 W limit and this layout has 860W).

Thanks all for the input, any further suggestions will be appreciated.

Don Mitchell

[GeoPowers]

Looks nice. I connected my panels together (in series for now), and then ran that to a switch (simpler IMHO), but can see the benefit of being able to isolate an individual panel if you wanted. I only run 2 225W Sanyo's, so not as important to isolate part of the array.

However, even though I wired the panels in series I set up my wiring as if they were in parallel in case I ever change my mind. With you wiring up and running your panels in parallel, you may want to check your voltage drop using a calculator. The typically desired figure is a voltage drop of <3%. With AWG 8 and a 40 ft run to the charge controller (20'x2), AND 40' runs from the panels to the combiner, you may be over this amount. Apologies if you've already done this- it's just that that seems like a long run for a parallel, low voltage connection. Not sure about the Flexmax 80, but the Flexmax 60 will take an AWG 4. Of course, if you switch to a series/parallel or series type connection your voltage drop will be greatly reduced.

Looking forward to pic of the completed project!

Frank

[GeoPowers]

By the way, I assume everything after the batteries is simplified in your diagram, i.e. not showing fuses actually in place, or that you may actually have a power bus bar with an additional fuse, etc.

Frank

[hamradiosailor]

I also am in the final planning stages, design II, for solar panels for a Beneteau 46 so thanks for your post and design. I am now thinking of 4 panels, Panasonic/Sanyo 240's, and two controllers, Morningstar Tristar MPPT 45's. I believe that I will put the solar panels in pairs in series to keep the above deck wiring simpler, 4 leads instead of 8. Then each pair will have its own controller. I have a physics background, but I am not that knowledgable in boat electrical matters. I believe that the parallel operation of the Tristar controllers will work, and the remote panel monitor/control works for multiple controllers. This will give 4x240 = 960watts rated maximum, which I hope is not overkill for my 4x200 A-h house system.

Last week the "design I" plan was to go with two Sunpower 327 panels, with 20% efficiency, and one Tristar 60. This would have yielded approximately 2x327 = 654 watts. Probably enough power for us, but I could not get the Sunpower 327 panels at a reasonable price. The local Florida Sunpower dealer/installer said that he was going to charge $1260, but then when it came time to pick them up the charge became $1450 per panel, or $4.43 per watt. That was just too much. Yesterday after reading your details, I decided then to go with the almost as efficient 19% panels by Panasonic/Sanyo at a price of about $525 each, or $2.18 per watt. Any ideas would be welcome from anyone since this is not really something that I know a lot about.

[roetter]

I used 5xKD190 (950W) in series on an Outback 80 with great results. Great controller and very programmable.
- Makes cabling simple - I used the installed KD connectors to connect them in series. I bought some length of solar cable and two MC connectors. Crimped the connectors onto the cable and ran them to fuse and Outback. This reduces the chance of faults due to flaky connections.
- Only one controller to deal with. Had a remote in the salon that I would check all the time.
Adjusted the bulk voltage to 14.6V. Never had to top up water on the 840Ah batteries.
- Got over 4.5KW/h per day.

[settingsun]

That's a good amount of solar, but I'm not sure you really need two charge controllers. It seems unnecessarily complicated.

We have lived almost entirely on solar (11 months at a time, 7 months at a time, 5 months at a time) over the last 3 years on our sailboat, and we have just one charge controller. It's a Xantrex 60 amp MPPT controller.

We have the same size Outback controller on our fifth wheel trailer (which we have lived in, solar-only, for over 1,000 nights). Both have worked flawlessly.

We have 555 watts of solar on the boat and it is enough to live without thinking about power use at all, as long as we keep the standalone freezer off. So your 860 watts ought to allow you to run your freezer too, no problem. Jealous!! (We sometimes run 2 laptops for 12 hours a day or more plus watch movies and run the stereo).

Our panels provide awesome shade over the jump seats on the back of the boat. We don't need any kind of bimini shade cover where there are -- they ARE the bimini!!

The biggest issue for us was getting the charge controller close enough to the batteries (we had to move it after the initial installation), and using big enough wire on that run.

There were some comments about putting pairs of panels in series, and from what I've seen, the problem with running any panels in series is that if one is shaded even just 10%, all panels connected to it serially will shut down. A little smidge of shade from the boom or the mast, and you've lost that panel or that solar array.

We swing 90 degrees at anchor, so it is very hard to keep shade off the panels at times. The mast is very tall and even when the boom is pulled away, shade creeps onto the panels.

We've done quite a bit of testing and have lots of info about our experiences with our three solar installations (two on trailers and one on our boat) on our website:

Arch and panel installation on our boat

Panel installation on our two trailers

Specific tests regarding parallel versus serial are on the second link - we learned that lesson on our trailer (with series panels) while parked next to good friends who had the identical setup in parallel... Shocking how little shade kills a panel. A 4"x4" square of shade will shut down a panel. Hooked to another panel in series, that little shade will shut down the 2nd panel too...

[s/v Jedi]

Originally Posted by settingsun

There were some comments about putting pairs of panels in series, and from what I've seen, the problem with running any panels in series is that if one is shaded even just 10%, all panels connected to it serially will shut down. A little smidge of shade from the boom or the mast, and you've lost that panel or that solar array.

We swing 90 degrees at anchor, so it is very hard to keep shade off the panels at times. The mast is very tall and even when the boom is pulled away, shade creeps onto the panels.

That depends on how old your panels design is. They introduced bypass diodes to tackle this problem and even make it so that series outperforms parallel, by segmenting panels into strings that get isolated when they get shading.

Somebody reported that all panels of the past 25 years have these bypass diodes, so it's a matter of checking the documentation.

[settingsun]

Well, we've watched our solar charge controller as the mast shade swings across the panels, and the amperage going into the batteries drops significantly. The panels are 3 years old from Kyocera. Kyocera still sells them.

You can see what the shade looked like on the panels and how the amps going into the batteries changed at the time of observation on this link (20% down the page):

Marine solar power installation

On that page I also give inks to two very interesting articles that describe the effects of shade on solar panels. One comes from the Physics department at the University of Arizona from a paper presented in 2010.

The Kyocera documentation also goes into detail about how partial shade affects solar power production in their panels.

All of our boat panels are Kyocera (current trailer has 1 Kyocera and 3 Mitsubishi) - they make pretty good panels and the ones made by both of those companies in the last 3-5 years probably have the latest technological advancements built in.

[s/v Jedi]

Originally Posted by settingsun

Well, we've watched our solar charge controller as the mast shade swings across the panels, and the amperage going into the batteries drops significantly. The panels are 3 years old from Kyocera. Kyocera still sells them.

You can see what the shade looked like on the panels and how the amps going into the batteries changed at the time of observation on this link (20% down the page):

Marine solar power installation

On that page I also give inks to two very interesting articles that describe the effects of shade on solar panels. One comes from the Physics department at the University of Arizona from a paper presented in 2010.

The Kyocera documentation also goes into detail about how partial shade affects solar power production in their panels.

All of our boat panels are Kyocera (current trailer has 1 Kyocera and 3 Mitsubishi) - they make pretty good panels and the ones made by both of those companies in the last 3-5 years probably have the latest technological advancements built in.

Yes, your panels probably have bypass diodes. I think you have 24V panels? I don't know how they are configured, but at 24 V you might only have one string of cells in each panel. This means that you loose complete panel output with shading no matter how you connect it. But in series config, the unshaded panels would still produce full output and a bypass diode activates as a shunt to skip the shaded panel. You lose a little power in that diode, but you win back enough as the current is much lower with series connection, minimizing cable and connector losses.

From you diagram, I think it would be easy for you to try a series setup. The controller stores kWh production for the past 128 days or so, making it easy to determine if it's an improvement or not.

[settingsun]

On our trailer we have one 130 watt Kyocera panel (circa 2007) and three 120 watt Mitsubishi panels (circa 2008). All are 12 volt and all are wired in series.

I did a test. You can see it on my RV solar panel installation page about 80% down the page. Here's what I did and what happened:

The panels were in full sun in Arizona in January at 9:30 in the morning getting 12.8 amps. I stood on the roof of the trailer and used my body to shade a small portion of one corner of one panel. The amps going to the charge controller dropped to 1.6 amp.

My neighbor, who had the exact same solar panel configuration on his roof except wired in parallel, got on his roof and did the same thing at the same time. He went from getting 12.8 amps to getting 10 amps.

So when we put solar on our boat we used three 24 volt 185 watt panels from Kyocera (circa 2010) and wired them in parallel.

As an experiment, I took note of the shade on the three panels as the mast slowly crept across them at anchor early one morning in Huatulco Mexico in January.

Full sun: 22 amps
One panel partly shaded: 15 amps
Two panels partly shaded: 9.5 amps

The photos on my website's marine solar installation show the exact amount of shade we're talking about -- not much.

If the panels had been wired in series, the drop would have been like our trailer -- Full sun, 22 amps, one panel shaded, 1 amp, two panels shaded 1 amp.

The paper written by the Physics department at the University of Arizona that I link to on my marine solar installation page was written about the banks of solar panels used in sunny states like Nevada (I've seen rows of panels going on for acres -- it's quite a sight).

The problem they were referring to was that when the rows are spaced too close together and the sun is low in the sky, each row of panels partially shades (like by an inch or two) all the panels in the row behind it. This knocks out the whole array. Read the paper - it's fascinating.

There may be panels out there that don't do this. But when I went to Northern Arizona Wind and Sun in Flagstaff Arizona to get all our solar gear for each of our three solar panel installations, they weren't selling them there. And that's a very reputable company that outfits commercial buildings with solar power.

The other document I link to on my site shows exactly how little shade is needed to reduce the output of a panel by 50%. Half of the width of one row of boxes on a panel. Or half of one box.

My personal observations of the behavior of the solar panels wired in series on my trailer and of the solar panels wired in parallel on my sailboat make me believe that wiring in parallel is superior because if one panel is knocked out of the system by partial shading it doesn't take out all the other panels with it...

We've lived with solar power on our boat and trailer very happily for 6 years without needing hookups... the series wiring on our trailer is not a problem because we never park under trees... but I would humbly recommend that anyone wiring a boat do the wiring in parallel... I certainly would if I outfitted another boat!!!

[s/v Jedi]

Originally Posted by settingsun

On our trailer we have one 130 watt Kyocera panel (circa 2007) and three 120 watt Mitsubishi panels (circa 2008). All are 12 volt and all are wired in series.

I did a test. You can see it on my RV solar panel installation page about 80% down the page. Here's what I did and what happened:

The panels were in full sun in Arizona in January at 9:30 in the morning getting 12.8 amps. I stood on the roof of the trailer and used my body to shade a small portion of one corner of one panel. The amps going to the charge controller dropped to 1.6 amp.

My neighbor, who had the exact same solar panel configuration on his roof except wired in parallel, got on his roof and did the same thing at the same time. He went from getting 12.8 amps to getting 10 amps.

So when we put solar on our boat we used three 24 volt 185 watt panels from Kyocera (circa 2010) and wired them in parallel.

As an experiment, I took note of the shade on the three panels as the mast slowly crept across them at anchor early one morning in Huatulco Mexico in January.

Full sun: 22 amps
One panel partly shaded: 15 amps
Two panels partly shaded: 9.5 amps

The photos on my website's marine solar installation show the exact amount of shade we're talking about -- not much.

If the panels had been wired in series, the drop would have been like our trailer -- Full sun, 22 amps, one panel shaded, 1 amp, two panels shaded 1 amp.

The paper written by the Physics department at the University of Arizona that I link to on my marine solar installation page was written about the banks of solar panels used in sunny states like Nevada (I've seen rows of panels going on for acres -- it's quite a sight).

The problem they were referring to was that when the rows are spaced too close together and the sun is low in the sky, each row of panels partially shades (like by an inch or two) all the panels in the row behind it. This knocks out the whole array. Read the paper - it's fascinating.

There may be panels out there that don't do this. But when I went to Northern Arizona Wind and Sun in Flagstaff Arizona to get all our solar gear for each of our three solar panel installations, they weren't selling them there. And that's a very reputable company that outfits commercial buildings with solar power.

The other document I link to on my site shows exactly how little shade is needed to reduce the output of a panel by 50%. Half of the width of one row of boxes on a panel. Or half of one box.

My personal observations of the behavior of the solar panels wired in series on my trailer and of the solar panels wired in parallel on my sailboat make me believe that wiring in parallel is superior because if one panel is knocked out of the system by partial shading it doesn't take out all the other panels with it...

We've lived with solar power on our boat and trailer very happily for 6 years without needing hookups... the series wiring on our trailer is not a problem because we never park under trees... but I would humbly recommend that anyone wiring a boat do the wiring in parallel... I certainly would if I outfitted another boat!!!

The parallel test results are as expected: output from one panel is lost. Because they are connected in parallel, it means that 25% of array output current was lost.

The series test results are not as expected. A series connection means that the array output current is the same as that of a single panel... it is the voltage that gets multiplied. This means that at equal, full power output to your neighbour, you should have seen 3.2A instead of 12.8A. But the array voltage would have been 4 times as high.

I think you compared the current from controller to the battery? That would make sense. You do need a suitable MPPT controller for that which can deal with the high input voltage and convert it to battery charge output voltage.

Your test indicates you have that controller. Assuming the shade was only on one panel, the only conclusion can be that the bypass diode is blown or missing. You can try to shade another panel...
This has been tested again and again, so it really isn't me trying to fool you; I am just an electronics engineer.

The scientific paper is correct of-course, but you can't apply that outcome to this. They have panels shading all the other panels in the next row and so on.

[settingsun]

Well, my degree is in Physics, but what matters most in this subject is real world performance, not theory.

I've posted the data from my test on a solar installation where the panels are wired in series. Perhaps you, or someone else, can post their data from the same test done on a different system where the panels are wired in series. That would be really helpful here!!

On our trailer with the 490 watts of 12v panels wired in series, we have an Outback FM60 MPPT solar controller.

On our boat with the 555 watts of 24v panels wired in parallel, our charge controller is a Xantrex XW-MPPT 60-150 charge controller.

These are both excellent controllers and they have worked well for us without any failures.

I doubt the blocking diodes on our Kyocera panels are blown on our trailer. However, if such an important component failed so easily during regular use, I would hesitate to do an installation that depends entirely on that part working.

Bottom line, we've lived with solar power on trailers and a boat for 6 years, using systems wired both in series and in parallel, and my personal conclusion is that a few square inches of shade on one panel in a series-based system will reduce the power production much more significantly than the same shade on one panel in a parallel-based system.

I offer this information just to help others who are planning to install a new system. It doesn't matter to me what anyone else chooses for their system -- my systems work flawlessly already.

[s/v Jedi]

Blocking diodes are not the bypass diodes. Most modern panels don't have any blocking diodes anymore.

There have been many posts about successful series configs, but people won't post that again and again. May be the search function would bring them up.

[settingsun]

For those that are interested in series versus parallel wiring of solar panels, I just got off the phone with an engineer at Northern Arizona Wind and Sun, a well respected company that does huge solar projects for commercials buildings as well as little ones for RVs and boats.

They said that the behavior I saw with our series-wired solar panels on our fifth wheel trailer (12.8 amps in full sun, 1.6 amps when just a few inches of one corner of one panel was shaded) was the result of the bypass diodes in the panels doing their job!!

If the bypass diodes in the panels were not working or were not present in the panels, the current flow would have dropped to zero.

He said you are definitely better off with a parallel installation of solar panels if there is any possibility that small portions of any of the panels will be shaded at times during the day.

I also found two interesting websites that discuss bypass diodes in solar arrays:

A technical discussion of bypass diodes

Notes on how to install external bypass diodes in a solar panel installation

Looking at the notes on installing external bypass diodes, it seems to add a level of complexity to the installation that can be avoided by installing the panels in parallel. For starters, the bypass diodes have to be sized correctly, and you have an extra bit of wiring to contend with. We were able to complete the actual wiring of our solar installation on our boat in a day or two... not sure I could have persuaded my husband to go hunt down the right Schottky diodes and then install them in parallel to each panel...

The advantage of an in-series installation is that the wire can be higher gauge (thinner and more pliable to work with and cheaper), but you can get that advantage in a parallel installation by going with 24 volt panels instead of 12...