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Old 13-12-2011, 19:05   #1
R_C
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First solar installation

I have been doing a lot of research for my first solar installation and I have a few questions. I plan to use two Kyocera 135W panels and a Blue Sky SB3024iL MPPT charge controller that can handle 12/24V. To minimize wire size I will connect the panels in series and send 24V to the charge controller to charge our 12V house bank.

If the panels are rated 135W, 7.63A, and 17.7V, that gives me 270W in series. Is the maximum amperage to the controller 11.25A (270W / nominal 24V)? 24V at 11.25A on 10AWG at 3% loss gives me a maximum wire run of 38’ from panels to charge controller. Am I on the right track?

Initially, I plan to set the panels up on our dinghy’s cradle while at anchor then secure and store the stacked panels below the dinghy while under way. I plan to use 10AWG marine boat cable and would like to disconnect and stow the cable while under way. Is there a good marine grade polarized quick-disconnect connecter I can use on 10AWG wire? Is a solar panel with a junction box a more flexible solution on a boat than one with the new MC4 connector?

I have a power bus bar that I use to connect the house battery bank to multiple charging sources: alternator, Iota 90A, and Xantrex 40A. I’ll also connect the Blue Sky SB3024iL’s output to the power bus bar and I’m adding a Xantrex echo-charger to keep the start battery topped off. If the solar panels are charging, will there be any problem if I start the genset and the Iota 90A charger is on? How will the Iota or Blue Sky react if the other is also charging? Thanks for any insight.
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Old 13-12-2011, 19:07   #2
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Re: First solar installation

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Originally Posted by R_C View Post
Initially, I plan to set the panels up on our dinghy’s cradle while at anchor then secure and store the stacked panels below the dinghy while under way.
Powerboat?
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Old 13-12-2011, 19:18   #3
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Re: First solar installation

Yes, this is a trawler. The boat deck where we secure the dinghy is the best place for the panels right now. Later, we might add a rack above the bimini.
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Old 13-12-2011, 20:34   #4
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Quote:
Originally Posted by R_C
I have been doing a lot of research for my first solar installation and I have a few questions. I plan to use two Kyocera 135W panels and a Blue Sky SB3024iL MPPT charge controller that can handle 12/24V. To minimize wire size I will connect the panels in series and send 24V to the charge controller to charge our 12V house bank.

If the panels are rated 135W, 7.63A, and 17.7V, that gives me 270W in series. Is the maximum amperage to the controller 11.25A (270W / nominal 24V)? 24V at 11.25A on 10AWG at 3% loss gives me a maximum wire run of 38’ from panels to charge controller. Am I on the right track?

Initially, I plan to set the panels up on our dinghy’s cradle while at anchor then secure and store the stacked panels below the dinghy while under way. I plan to use 10AWG marine boat cable and would like to disconnect and stow the cable while under way. Is there a good marine grade polarized quick-disconnect connecter I can use on 10AWG wire? Is a solar panel with a junction box a more flexible solution on a boat than one with the new MC4 connector?

I have a power bus bar that I use to connect the house battery bank to multiple charging sources: alternator, Iota 90A, and Xantrex 40A. I’ll also connect the Blue Sky SB3024iL’s output to the power bus bar and I’m adding a Xantrex echo-charger to keep the start battery topped off. If the solar panels are charging, will there be any problem if I start the genset and the Iota 90A charger is on? How will the Iota or Blue Sky react if the other is also charging? Thanks for any insight.
Someone will correct my math if I am wrong but in a series circuit volts is doubled watts is constant.

You will get 35.2v @ 7.63 amp and 270w at the controller.

In parallel you would get 17.7v @ 15.26amp and 270w at the controller.

Either way you get the same watts because W=VA

The 12/24 comment may be confusing you. That is the output voltage of the controller.

The controller in question will accept up to 57v input with recommended input of 45v.

Wiring your panels in series is the way to go. The wire between the panels and the controller should be sized for 35.2v @ @7.63amp

Here is the data sheet.

http://www.blueskyenergyinc.com/uplo..._datasheet.pdf
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Old 13-12-2011, 20:35   #5
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Re: First solar installation

My concern would be damage to the panels while underway. This would certainly be less of a problem on a trawler, however, it still pays to remember that the top layer of a solar panel is glass.

I would recommend starting with the rack over the bimini, and forgetting about stowing the panels everytime the boat gets underway.

Here's the system:
1. Build the rack.
2. Install the panels.
3. Enjoy the power.
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Old 13-12-2011, 21:21   #6
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Re: First solar installation

Yeah don't try to move those panels around. I have two of the same kyocera models you're talking about. They are large, have sharp edges, and a pain in the ass to find a nice location for. I take mine down when the weather calls for 45+ knots otherwise out they stay. Find a place for them to live forever.
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Old 14-12-2011, 05:41   #7
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Re: First solar installation

I have installed the Kyocera 135W panel with the integral junction box. You can connect the two panels in series through the junction box of one. Then the output can use MC4 connectors which are waterproof. These come with 10 or 12 gauge wire and given the 7.6 amp output as Ex-Calif correctly notes, either will work.

Wire the output of your controller to the DC buss, through a 30 amp fuse. The solar system will coexist fine with all of the other loads and charging sources.

David
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Old 14-12-2011, 18:59   #8
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Re: First solar installation

Thanks for the replies everyone. My problem with the bimini location is that the frame rocks a bit in a blow and that's when we like to fold it up to reduce our windage. The dinghy cradle is also the best place to minimize shadows on the panels.

My plan is to have a rack with protruding bolts secured to the bottom of the cradle where I will stack the two panels and secure with wing nuts while under way. I'll do something similar to secure when they are placed on the cradle at anchor. I'm also considering Anderson powerpole connectors so I can detach and stow the cable to the controller. We cruise 4 - 5 months a year and we'll stay in an anchorage for a week or more and in mooring fields for much longer so right now I'm not too concerned about moving the panels up and down about a foot between positions.

I like the flexibility of the junction box and they are only $5 more than the mc4 version panels. I think I've figured out the voltage drop. In series I will have 35.4V and 7.63A to the controller. At 50 feet of 10AWG that's less than a 3% drop.
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