Solar panel controller

[RainDog]

Originally Posted by northoceanbeach

how do you wire them all together? Do they all go to the MPPT Genusun controller and then that goes to the batteries? Or do I need separate MPPT controllers for each solar panel?

Assuming you are talking about 100-140 watt panels, the Genusun controllers are one-per-panel. You could buy several of them, or buy a single higher capacity controller and wire all the panels to it. If you are talking two panels, the cost is close. If you get to three, the single controller is much less expensive.

[northoceanbeach]

I was thinking two. I have the 123 watt panel. I saw a really nice 60 watt flexible panel the other day. That would put me at 180. That's better right? I can keep the hard panel stern mounted and the flexible over the cabin.

So I have the Genusun GV10 for the 123 watter. There isn't a huge selection of MPPT controllers around here but that same store just happened to have a gv-8 controller which would work for the 60 watt flexible.

So I wore each panel to the controllers and then just wire the controllers straight to the batteries? Do I actually hook the wires to the batteries or do I have some electrical box or a fuse or anything else that I need? Basically, how do I wire a solar panel to two batteriesL

[GILow]

If I were doing it I would ensure there was a fuse on the positive lead between the controller and the battery. And if you are going the dual controller path then a separate fuse for each controller. I also have a fuse between the panels and the controller, which is important, but in my setup that particular fuse is physically part of the controller. I don't like that setup because I am forced to carry spare fuses for the controller which are an unusual size and different to the standard I have used for the rest of the boat. Anyway, maybe tape a spare fuse to the cable near an inline fuse holder and put a few spares somewhere safe.

Slight aside, but you are discovering one of the values of windvane steering here. Probably too late to consider now given your timeline but you can see how taking the autopilot out of the equation now would change the figures in your favour. From what I have read of the journey you are about to do I would at least make sure I was set up for sheet to tiller steering as a backup if the power gets low.

Matt


Sent from my iPad using Cruisers Sailing Forum

[zboss]

Originally Posted by GILow

If I were doing it I would ensure there was a fuse on the positive lead between the controller and the battery. And if you are going the dual controller path then a separate fuse for each controller. I also have a fuse between the panels and the controller, which is important, but in my setup that particular fuse is physically part of the controller. I don't like that setup because I am forced to carry spare fuses for the controller which are an unusual size and different to the standard I have used for the rest of the boat. Anyway, maybe tape a spare fuse to the cable near an inline fuse holder and put a few spares somewhere safe.

Slight aside, but you are discovering one of the values of windvane steering here. Probably too late to consider now given your timeline but you can see how taking the autopilot out of the equation now would change the figures in your favour. From what I have read of the journey you are about to do I would at least make sure I was set up for sheet to tiller steering as a backup if the power gets low.

Matt


Sent from my iPad using Cruisers Sailing Forum

Personally, I would fuse both the neg and the pos. It doesn't cost much more. We lost all of our home electronics from a lightning strike where the current traveled on the neg line. That's an extreme example, but it's cheap insurance.

Remember to select fuse size based on either the wire amperage or the max device amps, whichever is lower. You should not be using a wire with lower amperage than the device could deliver but its worthwhile pointing out.

[GILow]

Originally Posted by zboss

Personally, I would fuse both the neg and the pos. It doesn't cost much more. We lost all of our home electronics from a lightning strike where the current traveled on the neg line. That's an extreme example, but it's cheap insurance.

Interesting dilemma. I wonder how the risk posed by the additional potential points of failure introduced by additional fuse fittings balances against the likelihood of protection against a relatively unlikely lightening strike?

Personally, I would go for the less complex system, but we are not in an area with much lightening activity.

Matt

[onestepcsy37]

Originally Posted by zboss

Personally, I would fuse both the neg and the pos. It doesn't cost much more. We lost all of our home electronics from a lightning strike where the current traveled on the neg line.

Good advice based on personal experience.

On the lightning damage thread that was recently running here I posted about how the only electronic device that survived our direct hit was the Navtex, which had been fused on both the positive and negative side from the factory. The negative side fuse was blown; replaced it and the Navtex ran like nothing had happened.

[svlamorocha]

Originally Posted by hellosailor

A 123 watt panel will provide perhaps 8 amps in full sunlight, which will translate into about 40 amp hours per day in full sunlight, assuming unobstructed (no shadows) panel. The Genasun MPPT might boost that 10% to some 44 amp hours a day.

Now sharpen a pencil and do the math, what is the load, in amp hours, of all the equipment that you plan to run, for the hours you plan to run it, every day? If it is less than 44 amp hours, your panel might suffice.

+1 on all that, but you you still need to allow some margin for the energy that will be wasted in the batteries (ie "charge efficiency factor") that becomes significant when you get the batteries over 85% every afternoon (good for the batteries but bad for charge efficiency)..

[over40pirate]

With a 123 watt panel, in full sun you will be putting out less than 10 amps. With 200 amp house batteries, I don't think a controller is necessary.
You will also get more output, without the controller, especially if you don't have a diode in the circuit.
When I used solar, I had a diode, but wired in a switch, which allowed me to bypass it, if I wanted the max charge. I think the diode cut the charge voltage by .6 volts.
I of course stayed on top of my battery voltage.
Using the wind generator, I also had the option to bypass the diode. Be sure not to forget to use the diode when the wind dies!
Bypassing the diode, also enabled me to jump start the windmill, when there wasn't enough wind to get it started, but enough, that when it started, to generate a small amount of power.

[zboss]

Originally Posted by GILow

Interesting dilemma. I wonder how the risk posed by the additional potential points of failure introduced by additional fuse fittings balances against the likelihood of protection against a relatively unlikely lightening strike?

Personally, I would go for the less complex system, but we are not in an area with much lightening activity.

Matt

Its not a difficult or complex add-in..but the payoff may save your electronics. Its my understanding, and experience, that current increases are experienced by the negative side first. This is why I do both neg and pos.

[TacomaSailor]

Just to repeat from another of my recent posts - have been living with solar panels for 15-years, never need the engine alternator, and never need shore power.

We have a dead simple 1999 Trace C-40 panel controller that manages 4x125 watt Kyocera panels. It works great!

Our first set of six T-105 6v lead acid batteries lasted 7-years and our current batteries are 6-years old and still seem perfect based on every known test.

I am hard pressed to understand how everyone makes the solar business so complicated, nor can my brother on a 42' boat and a friend on a 47' boat. All are systems are 15 or more years old and still work perfectly.

A lot of very knowledgable folks here can provide very sophisticated, and complicated, advice for building a state of the art solar panel system. I am sure they know what they are talking about.

I also know our stone simple system has worked perfectly for 15-years including 6-years of full time life aboard.

We use an ST-1000 connected to our Sailomat windvane to drive the boat in light air conditions. It consumes less than 1/2 amp while driving our 40' 25,000 pound boat downwind with the chute up in 4' seas.

I'd guess your ST-2000 would not used too much more on your smaller lighter boat.

[northoceanbeach]

Cool. Can I have the panels hooked to the batteries when I am on shore power?