Challenges with Solar on boats

[StuM]

Originally Posted by CaptJamesCook

So cool Lifesmiles. Will you leave your boat to me in your will?

For a 40' if I divide your system by 3 I would not have enough room for the panels..

You're talking about square footage. On a 40 footer, you only have about 1/9th the available area of a 120 footer

[john61ct]

Yes you'll need to buy spares, and taking a chance with your batteries, might as well get a Victron.

Sometimes you see a decent older PWM unit at that sort of price, but you need to know what's what.

Couple months ago I picked up over a dozen Specialty Concepts ASC with the "AF" option for under $6 each.

[foggysail]

Originally Posted by Kenomac

Install separate controllers for each panel to eliminate as many shading issues as possible.

Only if you have your panels wired in series will individual controllers minimize shading issues. But so will parallel connected panels.

And wiring with individual controllers comes with wiring and controller placement (real estate) headaches. Rather than making a general statement "Install separate controllers for each panel", judgement should be reserved to the installation as how best the panels should be connected and how many controllers should be considered.

[Kenomac]

Originally Posted by foggysail

Only if you have your panels wired in series will individual controllers minimize shading issues. But so will parallel connected panels.

And wiring with individual controllers comes with wiring and controller placement (real estate) headaches. Rather than making a general statement "Install separate controllers for each panel", judgement should be reserved to the installation as how best the panels should be connected and how many controllers should be considered.

Solbian designed the system for maximum production, minimun space and invisible visual. So far, it looks like they got it right. The goal was 450w, minimal shading and not to have the boat looking like a solar farm.

[jheldatksuedu]

I just had a thought, let me know what you think about this.

Have the 4 batteries in my system wired in series for charging by one solar charging system, operate off of one of the batteries at a time for the house power, have it switched both negative and positive terminals, so you can easily change from one to another battery to share the discharge, basically the batteries and the charging system are electrically floating, with the entire system grounded by the negative terminal of which ever battery is selected and being used by the house. The controller would be "grounded" to the lowest battery negative and that would be 0-36 Vdc below the boat ground. I would not think that would be a real problem as long as the controller is electrically isolated in it's mounting.

This would allow a much simpler high voltage (48Vdc) charging system, Basically you would almost have to have a boost controller, then you could operate with the panels connected in parallel or series combination, what ever you think is best for your situation and panel shading.

The controller I was looking at can operate on up to 6 batteries in series, that's what gave me this thought.

If I went with the Victron controller I would have to get a device to program it, another $70 since I don't have or ever plan to have an I-phone. I've had fairly good luck with cheap Chinese stuff. sure some stuff is junk but overall worth the savings in my opinion. I certainly got my share of US made junk too. Many times in the past China has been the most advanced society on earth, I think they are heading that way again. Anyway that's not the question, the question is about the 4 battery in series charging idea with a switchable single battery for house power and the sort of floating ground. It seems reasonable to me.

Please open fire and shoot holes in my idea if it is warranted. I could see having another smaller "electrically floating" charging system that might be applied to an individual battery to top it up, if one gets more discharged then the rest.

[Kenomac]

Why not buy a Genasun GV-Boost controller and be done with it? Many times in life, it pays to spend a little more because you end up saving in the long run.

Use an extra $50 from your SS check and buy something better that doesn't need programing.

[senormechanico]

Originally Posted by socaldmax

I even had one customer call me late at night on a very bright full moon night and tell me he was getting a very slight charge from the moonlight! I jokingly told him he was crazy and he snapped a pic with his phone. He was only producing .1A, but we were both laughing because it was something! That was on a 420w system feeding a single MPPT controller.

We saw the same thing under full moon while in Mexico.
That was before MPPT controllers or camera phones. I even threw a towel over most of my 470 watt array (previous boat) and it want to 0.0A
To this day, most people laugh at it, but I SAW it with my own eyes.

[jheldatksuedu]

Concerning buying an expensive controller, many times that is true that they might last longer, but also many times I have had success with a cheaper device that is basically an electrical copy, here this device is much more versatile and 1/5 the cost, so I could easily buy and have a spare. I've had many more of these cheap Chinese electrical things last without any failure at all than the number that have failed. Often if it does fail I have been able to replace the part that failed and have the system back up and running and still be way ahead financially. It's a trade off, I"m not trying to convince others I'm right but it works for me. But then I am a jack of all trades and electrical repair is one of them.

This type of financial choice has helped allow me to have a farm, a large sailboat, hundreds of other things, 50 antique sports cars and trucks all paid for and even not have an income for over 10 years of my life when other people are normally working. Sure I worked during those years, worked on stuff I owned and maybe bought cheaply because they needed work, but I enjoyed it.

Once again this is not the question, tell me about the 4 battery in series idea.

[jheldatksuedu]

Answering my own question, I'm pretty sure this system would only work well if the house battery is switched many times a day to tend to equal the discharge of all 4 batteries. I would assume, but don't know, that it would not work well to try to charge one battery that is somewhat discharged when it is in series with 3 other batteries that are still full charged. If anybody knows how that works please inform me.

My thoughts now are that this could still be a good idea if you basically work with a 48 volt battery bank and then have a 48 VDC to 12 VDC converter that supplies house power, thus equally discharging all batteries equally. This would also allow a backup plan of using a single battery if things failed.

When more power is needed than the dc to dc converter can supply you can basically go back to the running it off one battery, but having to be very careful about grounds when doing that.

[Kenomac]

Originally Posted by jheldatksuedu

Answering my own question, I'm pretty sure this system would only work well if the house battery is switched many times a day to tend to equal the discharge of all 4 batteries. I would assume, but don't know, that it would not work well to try to charge one battery that is somewhat discharged when it is in series with 3 other batteries that are still full charged. If anybody knows how that works please inform me.

My thoughts now are that this could still be a good idea if you basically work with a 48 volt battery bank and then have a 48 VDC to 12 VDC converter that supplies house power, thus equally discharging all batteries equally. This would also allow a backup plan of using a single battery if things failed.

When more power is needed than the dc to dc converter can supply you can basically go back to the running it off one battery, but having to be very careful about grounds when doing that.

I checked out your website. Nice boat!

[mitiempo]

Originally Posted by Kenomac

Why not buy a Genasun GV-Boost controller and be done with it? Many times in life, it pays to spend a little more because you end up saving in the long run.

Use an extra $50 from your SS check and buy something better that doesn't need programing.

The Victron controllers do not need programming any more than the Genasun controllers do. Genasun controllers are set at a particular charging voltage similar to Victron's factory settings. If however you wish to set the controller to the proper absorption setting for say a Trojan T-105 (which wants 14.8 volts) the Victron can be adjusted but the Genasun cannot be adjusted.

Victron controllers can be totally adjusted in 3 ways. With a computer connection and free software from Victron, with a MPPT monitor purchased separately, and with a bluetooth dongle and a smartphone.

[Baba Buoy]

Some cheap Chinese knockoffs are the exact same thing as the name brand. Many factories run unauthorized night shifts making the same item with same parts and sell it as a knock off.

[mitiempo]

Originally Posted by jheldatksuedu

I just had a thought, let me know what you think about this.

Have the 4 batteries in my system wired in series for charging by one solar charging system, operate off of one of the batteries at a time for the house power, have it switched both negative and positive terminals, so you can easily change from one to another battery to share the discharge, basically the batteries and the charging system are electrically floating, with the entire system grounded by the negative terminal of which ever battery is selected and being used by the house. The controller would be "grounded" to the lowest battery negative and that would be 0-36 Vdc below the boat ground. I would not think that would be a real problem as long as the controller is electrically isolated in it's mounting.

This would allow a much simpler high voltage (48Vdc) charging system, Basically you would almost have to have a boost controller, then you could operate with the panels connected in parallel or series combination, what ever you think is best for your situation and panel shading.

The controller I was looking at can operate on up to 6 batteries in series, that's what gave me this thought.

If I went with the Victron controller I would have to get a device to program it, another $70 since I don't have or ever plan to have an I-phone. I've had fairly good luck with cheap Chinese stuff. sure some stuff is junk but overall worth the savings in my opinion. I certainly got my share of US made junk too. Many times in the past China has been the most advanced society on earth, I think they are heading that way again. Anyway that's not the question, the question is about the 4 battery in series charging idea with a switchable single battery for house power and the sort of floating ground. It seems reasonable to me.

Please open fire and shoot holes in my idea if it is warranted. I could see having another smaller "electrically floating" charging system that might be applied to an individual battery to top it up, if one gets more discharged then the rest.

You wouldn't need a boost controller, just a MPPT controller that will charge a 48 volt bank. Would be expensive though. Victron's 150/35 ($347 US) will charge any battery bank - 12,24,36, or 48 volts, as long as the solar array is at a higher voltage.

Victron has a DC-DC converter for 48/12 with 30 amp output for $282 US, and a 20 amp version for $137 US.

Then you run the problem of shading with series panels.

[john61ct]

I have yet to see **in the case of solar controllers** a cheap Chinese "electrical equivalent", even any attempt at a knock off.

I'm not saying they're bad because they're made in China, in fact as long as the design, specs and QC are handled by the Western firm concerned with brand reputation, lots of good stuff is made there.

The no-name Chinese units are just designed to be very cheap, don't have the programmability and don't last long.

Very easy for them to fail in a way that damages your bank.

I'm sure, just like with Japan and Korea, the situation will change over time, no aspersions on any of those great Asian manufacturing nations and economic power houses.

[john61ct]

As for the "discharge one at a time" idea, there is no reason to do this and many reasons not to.

In fact you will get much less total power storage doing it this way.

If you have a reason to go 24V, do it and stick to it. Lots of reasonably priced devices in that range, including buck converters to go down to 12V when needed.

48V gets a lot more expensive and not as great an advantage, unless you're talking a propulsion motor.