Solar panels

[guidera48]

Just got in my two 80w panels to be attached on my newly finished davits. Each has a 3ft wire with funky connectors. (MC4). I guess I will be hunting for an extention cable to reach the controller on the galley wall. I do have a couple of questions for you guys that have already made this trip.

Can I install them without wiring them:
I have to make brackets for the units and expect to have them out for the better part of a week end. Are they going to melt if they are not hooked up to the controller and battery?? Do I need to cover them?

Series or paralel:
Each unit has a male and female plug. I guess they would daisy chain. Unit A male plug to unit B female plug and unit B male to controller.

Thanks
Jose

 

[Ed Schenck]

What make panel Jose? And what are the approximate dimensions? I want to do something similar but have no plans for davits. And I often sail with the bimini folded up. Not a lot of options on a Cherubini.

 

[guidera48]

I just realized that each plug is pos or neg. I had assumed each cable had two conductors. I guess i will need a junction box made for this purpose. Back on the hunt

Ed. I have not opened the boxes yet. They arrived today while I was away on a job. I will inspect them tomorow and let you know. I selected this particular units because they had the right measurements for the space I have on the davits. I'll post pictures tomorow.

 

[Bill Roosa]

You can leave them un-wired (protect the ends though as they will be electrically hot) it will not hurt them. As far as how to connect them to the controler you need to know the controler max allowable voltage. Putting the panels in series may or may not exceed that voltage. If that checks out then it is pretty much an issue of how the panels get shaded on your particular boat.
If you think if the individual cells as 0.5 volt batteries. when you shade one cell the rest of the cells in that series string will basicly not be contributing to charging. Most panels are just one series string of cells so any shade on the panel pretty much kills it. Which is why the more expensive panels have lots of by-pass diodes. they allow current to flow around the shaded cells at low resistance and so preserve most of the charging capability. If you series connect the panels and you don't have those bypass diodes for each panel then shading will have a dramatic effect on your output. not so much with parallel as that setup acts like a bypass diode to begin with.

 

[Don12364]

If you bought panels described as suitable for charging 12 V batteries I strongly suggest you do not wire them in series because if you do you will only get half the current they are capable of supplying.
Most have somewhere about 39 cells per string and have an output voltage of 22 volts. The cells are not difficult to count.
Up on davits there will only be minimal shading so most of the available sunlight will be put to good use.
My panels came with a ready made connector. 4 wires were spliced into one wire with 4 connectors on one end and one output connector to the regulator on the other.
Don't use them without a regulator as they will boil your batteries.
I guess the regulator is what you referred to as the controller. Yours might be one of the modern MPPT (Maximum Power Point Tracking) ones which convert most energy into electrical power.
Your panels will come to no harm if left unconnected whilst in the sun.

Two 80 Watt panels will give over 9 amps in parallel in full sun but expect about 32Ah in total per 24 hours at your latitude on a cloudless mid-winter's day (15% of maximum) and 58Ah in total per 24 hours (27% of max) on a perfect midsummer's day. Not all days are perfect!
Two curves for Myrtle Beach latitude as taken from NOAA published data are attached.

 

[guidera48]

I finally had time to go by the warehouse and open my package.
Ed. The reason I purchased these is because I have about 36x60 open area and these two panels would fit properly. I had explored the idea of puting them over the Bimini top and I was going to use the 24 x 48 size.
I ordered Y cables to connect all the wiring. Looks like it is going to be cold this week (in the 50,s) end but I 'll try to get them up.
Thanks

 

[Ed Schenck]

Thanks Jose. I found the UL-Solar panels on the web. Two of those 80 watt panels should serve well in SC. I'm looking for something just so I don't have to worry about the bilge pump during the week at the slip. I want to leave the boat unplugged. So I am thinking the 60 watt at 26" x 26" would be a good size. The bimini frame would be perfect but then I can't fold it back. :cry:

 

[Mathurin]

Before you buy a charge controller, call the compagny that makes it and ask them if they ever had issues with high frequency interference. Electronic charge controllers are more efficient, but they have a tendency to produce interference in your VHF. A friend of ours could not use frequecys under chanel 68. Just to say how bad it was, his charge controller would affect our communication system to the point we could not emit if he was within 200 yards.

 

[Rick D]

Re: interference; oh swell. I just installed one. I hate VHF interference.