Challenges with Solar on boats

[jheldatksuedu]

Originally Posted by newhaul

This is true for the runs from panels to controller however the runs from the controller to the battery that losses are minimal to virtually nonexistent.

let's look at an imaginary typical system, 3 100 watt 12v panels = 8 amps per panel

installed in parallel at the back of a sailboat to reduce shading problems, thus 24 amps in a wire.

30 feet of wire from panels to controller to 4 batteries in parallel. 10 gauge wire can handle 55 amps and has 1 ohm/1000 ft, .03 ohms in 30 ft

wire loss = 24x24x.03 = 17.3 watts

wire loss percentage 17.3/300 = 5.67%

one website I just looked at said 3 to 5% is acceptable, so probably switch to 8 gauge, but we are just trying to illustrate a point here, so I won't re do the calculations.

-----------------

Now let's put the controller near the panels and increase voltage in the wire to the batteries to 48 volts in series, same 10 gauge wire.

300 watts/48 volts = 6 amps
loss is 6x6x.03 = 1.08 watts

wire loss percentage 1.08/300 =.0036%

Sure there's lot of things you can change here but this just looks at what could be considered a typical system and my proposed changes. I also just realized that the wire length needs to be doubled, you have to have 2 wires to make a circuit, that would double the loss, so definitely go to 8 gauge, but still the same dramatic difference for reasonable sized wires and system. So my system in addition could reduce the wire size needed and the expense of larger wires.

Do you still think you need to tell me to KISS?

[atlantical]

My shore power is on all the time, but my shore power is completely isolated from boat power, I dont have a mains charger charging my batteries just the solar. My shore power works the kettle the microwave, the power points the batteries do all the boat stuff.

[newhaul]

Originally Posted by jheldatksuedu

let's look at an imaginary typical system, 3 100 watt 12v panels = 8 amps per panel

installed in parallel at the back of a sailboat to reduce shading problems, thus 24 amps in a wire.

30 feet of wire from panels to controller to 4 batteries in parallel. 10 gauge wire can handle 55 amps and has 1 ohm/1000 ft, .03 ohms in 30 ft

wire loss = 24x24x.03 = 17.3 watts

wire loss percentage 17.3/300 = 5.67%

one website I just looked at said 3 to 5% is acceptable, so probably switch to 8 gauge, but we are just trying to illustrate a point here, so I won't re do the calculations.

-----------------

Now let's put the controller near the panels and increase voltage in the wire to the batteries to 48 volts in series, same 10 gauge wire. I

300 watts/48 volts = 6 amps
loss is 6x6x.03 = 1.08 watts

wire loss percentage 1.08/300 =.0036%

Sure there's lot of things you can change here but this just looks at what could be considered a typical system and my proposed changes. I also just realized that the wire length needs to be doubled, you have to have 2 wires to make a circuit, that would double the loss, so definitely go to 8 gauge, but still the same dramatic difference for reasonable sized wires and system. So my system in addition could reduce the wire size needed and the expense of larger wires.

Do you still think you need to tell me to KISS?

Ok first a 100 watt panel tops at 6 amps so we have 18 amps by using branch connectors we have three panels into one wire from them to controller. Placing the panels where you suggest would actually max at 20 ft of wire pos and neg from them to controller.
Now lets install the controller iaw manufacturers instructions : as close to the battery bank as practiceable.
Also I dont see your loss calculations for the wire from controller to battery bank.
I stand by KISS. ( increase wire to 6 gauge if you want or even 4 untill you get the minimal loss that you can live with.)
Renogy says 3% or less loss with 6 gauge wire.
https://www.renogy.com/calculators/#solar-cable

[hellosailor]

Am I the only one who remembers...

Put a pair of Solarstik's on transom mounts. 100W each and extremely unlikely to be in the shade most of the time. Probably available with twin 100W panels (200W total) on each if you ask them nicely. Solar Stik | Official Homepage

Not a perfect solution, because they ARE a premium product at a premium price. But they'll sell you a soup-to-nuts solution and answer the phone without grunting, too.

If you've got welding skills, you could DIY the same way, on dedicated poles or modified hoists, but it still wouldn't be cheap if you built it up the same way. That's the "no shade out there" price penalty.

[john61ct]

Originally Posted by Utahsailor

In my 12V system of 840W Kyocera panels, dual Morningstar controllers and 10 Trojan T105s, I have to add water every week. Today I added nearly 1/3rd gallon after 1-1/2 weeks. This seems excessive and I notice that the Morningstar are putting more amps into the batteries at nearly full charge than the Balmar controller on the engine or the Xantrex when hooked to shore power. Does this seem excessive?

Yes, any charge source should be configured to go to float as soon as the bank is full

Which is defined as the Absorb stage current in Amps has dropped to say 1.5% of the bank's AH capacity. You should get the precise number from the bank's mfg.

Some charge sources aren't that adjustable, so a crude approximation is required based on an "egg timer" approach, telling the charge source how long the Absorb cycle should be held.

You would then need to figure that guesstimation out, and it will vary with load usage patterns, weather etc.

[john61ct]

Originally Posted by atlantical

My shore power is on all the time, but my shore power is completely isolated from boat power, I dont have a mains charger charging my batteries just the solar. My shore power works the kettle the microwave, the power points the batteries do all the boat stuff.

So when you visit shore for a few hours, in cloudy weather your bank doesn't get recharged?

And while cruising or on the hook you have to make meals, even just a cuppa, using propane or the generator?

May I ask why you want to keep them separate? Not like getting them integrated is that difficult or expensive. . .

[john61ct]

Originally Posted by jheldatksuedu

I remember now why I wanted to go to higher voltage, it is efficiency, the loses in the wires are due to the current not the voltage, at higher voltage and reduced current you have much less loss. In this case the losses in the charging system could be 1/16 as much, a major improvement. It's I squared R. We are working with such small amounts of energy from a solar panel every improvement can be important.

But voltage drop between the panel and controller is not nearly as critical as between the SC and the bank.

Unless your main propulsion engine is indeed 48V, going that high just to save buying thicker copper just doesn't make sense.

[jheldatksuedu]

Originally Posted by newhaul

Ok first a 100 watt panel tops at 6 amps so we have 18 amps by using branch connectors we have three panels into one wire from them to controller. Placing the panels where you suggest would actually max at 20 ft of wire pos and neg from them to controller.
Now lets install the controller iaw manufacturers instructions : as close to the battery bank as practiceable.
Also I dont see your loss calculations for the wire from controller to battery bank.
I stand by KISS. ( increase wire to 6 gauge if you want or even 4 untill you get the minimal loss that you can live with.)
Renogy says 3% or less loss with 6 gauge wire.
https://www.renogy.com/calculators/#solar-cable

You just refuse to get it, you can't see the forest because your too busy beating your head against a tree, I'm asking for constructive criticism, I could care less that your 100 watt panel puts out 6 amps and I assume mine does 8, that's not the point here, I'm just giving an example, making up numbers off the top of my head, (100 watts divided by 12 volts is 8 amps) and I could care less that you use 6 gauge wire and my calculations were done with 10, I also could care less if a user manual says put the controller near the battery, I'm showing your that maybe you don't want to do that. And as far as not being concerned about losses between the panel and controller, granted that's not going to affect if the battery will charge but it still is a loss of energy and affects the entire efficiency of the system. It's still a loss, and could be major. That's one of the reasons that we might want to put panels in series, increase the voltage and reduce wire loss. But then have the risk of the entire system shutting down when one corner gets shaded. Basically, If you don't have anything constructive to say, then please just shut up.

I'm convinced that my system could work and reduce losses, might reduce cost but has to have a fancy switch. If you can show me why it would not work I'm all ears, but just criticizing my choice of 8 amp panels and 10 gauge wire in my imaginary example is not going to do that. 5% loss in the wires is said to be an acceptable amount, my system can reduce that to .3% giving you 4.7% more power to charge the batteries. If your system has only 2% loss in the wire this can still save you 15/16 of that loss. I'm not talking about trying to reduce losses in an already built system, I'm talking about designing a system that has less loss and maybe cost from the start.

You call yourself a Marine Service Provider, I certainly would have a hard time recommending your "service" to anybody. I really hate to lash out at somebody like this but sometimes I have to call a spade a spade.

[newhaul]

Originally Posted by jheldatksuedu

You just refuse to get it, you can't see the forest because your too busy beating your head against a tree, I'm asking for constructive criticism, I could care less that your 100 watt panel puts out 6 amps and I assume mine does 8, that's not the point here, I'm just giving an example, making up numbers off the top of my head, (100 watts divided by 12 volts is 8 amps) and I could care less that you use 6 gauge wire and my calculations were done with 10, I also could care less if a user manual says put the controller near the battery, I'm showing your that maybe you don't want to do that. And as far as not being concerned about losses between the panel and controller, granted that's not going to affect if the battery will charge but it still is a loss of energy and affects the entire efficiency of the system. It's still a loss, and could be major. That's one of the reasons that we might want to put panels in series, increase the voltage and reduce wire loss. But then have the risk of the entire system shutting down when one corner gets shaded. Basically, If you don't have anything constructive to say, then please just shut up.

I'm convinced that my system could work and reduce losses, might reduce cost but has to have a fancy switch. If you can show me why it would not work I'm all ears, but just criticizing my choice of 8 amp panels and 10 gauge wire in my imaginary example is not going to do that. 5% loss in the wires is said to be an acceptable amount, my system can reduce that to .3% giving you 4.7% more power to charge the batteries. If your system has only 2% loss in the wire this can still save you 15/16 of that loss. I'm not talking about trying to reduce losses in an already built system, I'm talking about designing a system that has less loss and maybe cost from the start.

You call yourself a Marine Service Provider, I certainly would have a hard time recommending your "service" to anybody. I really hate to lash out at somebody like this but sometimes I have to call a spade a spade.

Ok first off personal attacks are against forum rules .
Secondly you asked for opinoins and I provided one in the beginning you didnt respond.
Thirdly I make a living installing these systems and each is specific to customers needs and vessel.
Now to state my recomendation again. In my professional opinion with what you want to accomplish .
As I stated before hook your panels up in series to achieve the desired panel voltage (24,36,48 volts)
Run your ten gauge wire from the panel junction box to an appropriate mppt controller near the (4 12 volt batteries in parallel) large house bank. No muss no fuss problem solved.( why try to reinvent the wheel)

[StuM]

Originally Posted by jheldatksuedu

You just refuse to get it, you can't see the forest because your too busy beating your head against a tree, I'm asking for constructive criticism, I could care less that your 100 watt panel puts out 6 amps and I assume mine does 8, that's not the point here, I'm just giving an example, making up numbers off the top of my head, (100 watts divided by 12 volts is 8 amps)

If you don't even know the basics of the output of a solar panel, you are in no position to be designing an "off-the wall" system.

Hint: A "12V" panel, doesn't output anywhere near 12V. If you are working on that assumption, you are sadly mistaken in all of your conclusions.

[john61ct]

Originally Posted by jheldatksuedu

You just refuse to get it

Sorry man that stuff's just uncalled for, you're going to be alienating lots of people might be able to help you out down the road, not smart.

Originally Posted by jheldatksuedu

I'm asking for constructive criticism

And you're getting it, just not listening!

The controller needs to be right at the battery, because otherwise it doesn't even KNOW what the bank voltage even is, and won't charge properly. Same for temperature compensation.

If distances are extreme between the panels and the SC, then go up to 24V.

At least that's a standard for House systems, yes more expensive, but 48V is just cuckoo, so much is just not even available, or you have to go to the crazy EV world for stuff.

Not just load devices, but basic infrastructure like a battery SoC monitor.

Now, if you're spending tens of thousands on electric propulsion, fair enough.

But if you are just concerned about voltage losses, use fatter wiring like a sane person.

You do realize every CB, every buss, every switch has voltage losses right?

[mitiempo]

Originally Posted by jheldatksuedu

...... I could care less that your 100 watt panel puts out 6 amps and I assume mine does 8........

A 100 watt panel is approximately 5.5 amps at panel voltage, which is about 18 volts. You would nee a panel of almost 150 watts to get 8 amps.

You are going to a hell of a lot of trouble to eliminate a bit of wire loss that could easily be reduced with a larger wire.

[mitiempo]

Originally Posted by atlantical

I have two batteries, and one solar controller, so, my solar goes to battery one, only way I can charge both batteries at one time, is switch the main battery switch to both, what I may ad, is a switch splitting the cable from the solar, so with my battery switch off, I can chose what battery to charge, switch that switch from battery one, or battery two, and the main switch can be switched off, just now with that switched off, all i can charge is battery one. If I was to connect the positive from the solar to both batteries then I could never isolate them from each other.

Install an ACR between the batteries and the problem of charging both is solved.

[john61ct]

Or maybe put them together fulltime as a single bank.

What is your reason for treating them as two?

[mitiempo]

Originally Posted by Utahsailor

In my 12V system of 840W Kyocera panels, dual Morningstar controllers and 10 Trojan T105s, I have to add water every week. Today I added nearly 1/3rd gallon after 1-1/2 weeks. This seems excessive and I notice that the Morningstar are putting more amps into the batteries at nearly full charge than the Balmar controller on the engine or the Xantrex when hooked to shore power. Does this seem excessive?

The only way the Morningstar is putting more current into the batteries than the Balmar controlled alternator does is if the Morningstar is set at a higher voltage. At a given voltage the battery determines the current it will accept.

Batteries should not need as much water as your batteries do. Adjust the voltage of the Morningstar.