Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 12-02-2014, 12:35   #16
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Switch for solar panel circuit

Quote:
Originally Posted by Dsanduril View Post
There really isn't a point to a breaker/fuse on the panel side, there is an absolute need at the battery end. A short from battery to ground/negative can lead to tremendous currents and requires a breaker with a high AIC.

Solar panels, on the other hand, are current limiting devices by nature. If a panel is rated at 8A it will put about 9A into a dead short. So what size breaker do you put in for that condition? 8.5A? There really is no breaker or fuse you can put in to protect against a panel to ground short because the current will not increase above Isc. If you size a breaker/fuse at even just 110% of normal current it will never open/trip.
+1

Dave
__________________

__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 12-02-2014, 12:58   #17
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: Switch for solar panel circuit

I added a switch allows me to take the panels out of the circuit when the engine is running and able to kick out more amps and the smart regulator not be confused by the voltage of the "trickle charge" of the solar panels.
__________________

__________________
Sandero is offline   Reply With Quote
Old 12-02-2014, 13:01   #18
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Switch for solar panel circuit

Quote:
Originally Posted by Sandero View Post
I added a switch allows me to take the panels out of the circuit when the engine is running and able to kick out more amps and the smart regulator not be confused by the voltage of the "trickle charge" of the solar panels.
Why would it be " confused"

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 12-02-2014, 13:12   #19
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Switch for solar panel circuit

Quote:
Originally Posted by skipmac View Post
Hi Bill,

Glad you mentioned this point as it's something I've been thinking about as I finish the rewire of my boat. I plan to run alternator, solar and wind power outputs to a common bus and from there to a terminal fuse block on the battery. So that end of the hot wires will be protected but what about the other end?

For example, I have a 120 amp alternator and if the hot wire on that is shorted before it reaches the battery terminal fuse then that's a problem as well. But first, quick look at fuse options for that amperage I don't see any inline fuses that will work and installing a fuse block is not really the cleanest solution for my location. Maybe a terminal fuse on the stuc on the back of the alternator? Any other suggestions?
An alternator like a solar panel is a current limited device thus no requirement for a fuse at the alt or panel end. Battery end yes...
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 12-02-2014, 13:35   #20
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,674
Re: Switch for solar panel circuit

Quote:
Originally Posted by goboatingnow View Post
Why would it be " confused"
When there are multiple smart controllers operating simultaneously they can interact in odd ways. With the solar panels charging and engine alternator running (using identical controllers as it happens) into a mostly charged battery, when the regulator opens the solar panels the alternator load increases and the engine reacts to the load. When the panels kick back in the engine runs a little easier. This on-off-on-off loading on the alternator can be very annoying to listen to. So I switch the panels off at that time.

For the size of panels considered here I am guessing that the maximum total current (for both panels at short circuit - Isc) is under 15A. Any switch that is rated at 15A and above will work nicely. You absolutely don't need battery switches and heavy duty circuit breakers to switch this load. You do need fusing at the battery for just about everything. The standards have gotten tighter for protecting wires at the batteries so you might review your situation there.

Greg
__________________
CarinaPDX is online now   Reply With Quote
Old 12-02-2014, 14:33   #21
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,374
Re: Switch for solar panel circuit

Quote:
Originally Posted by Maine Sail View Post
An alternator like a solar panel is a current limited device thus no requirement for a fuse at the alt or panel end. Battery end yes...
Oh yea. Doh! I knew that.

And since I will of course have the wire properly sized for the full output of the alternator, if it does short out then there will be no generation of smoke.
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 12-02-2014, 15:02   #22
Registered User

Join Date: May 2011
Posts: 44
Re: Switch for solar panel circuit

A mildly circuitous but always informative thread. However, I still have not come across a light duty switch (say 15A) that will take 8 ga wire; can I thin the strands at a terminal??
__________________
seadrift is offline   Reply With Quote
Old 12-02-2014, 15:09   #23
Registered User
 
jkindredpdx's Avatar

Join Date: May 2011
Location: Portland, OR, USA
Boat: Hallberg Rassy 35'
Posts: 1,047
Images: 5
Re: Switch for solar panel circuit

I have a water resistant plug through the deck between the panels and controller... so I just unplug the panels
__________________
http://www.sednahr35.blogspot.com/ Jim K.
jkindredpdx is offline   Reply With Quote
Old 12-02-2014, 15:20   #24
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,374
Re: Switch for solar panel circuit

Quote:
Originally Posted by seadrift View Post
A mildly circuitous but always informative thread. However, I still have not come across a light duty switch (say 15A) that will take 8 ga wire; can I thin the strands at a terminal??
Can't you just use a circuit breaker (which is also a switch) with screws? Then crimp an eye fitting with the appropriate sized hole onto the 8 gauge wire?
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 12-02-2014, 16:39   #25
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,674
Re: Switch for solar panel circuit

Quote:
Originally Posted by seadrift View Post
A mildly circuitous but always informative thread. However, I still have not come across a light duty switch (say 15A) that will take 8 ga wire; can I thin the strands at a terminal??
Switches with screw terminals are easy to find. Just one example:

Heavy Duty 20A 125V 15A 250V SPST 2 Terminal on Off Toggle Switch with Plate | eBay

Then use a sealed ring terminal for 8ga wire and #10 screw:

Heat Shrink Ring Terminal 8 AWG 10 Stud Ring Pink 5 | eBay

Greg
__________________
CarinaPDX is online now   Reply With Quote
Old 12-02-2014, 17:02   #26
Registered User

Join Date: Feb 2014
Location: NC
Boat: Prout 34
Posts: 32
Re: Switch for solar panel circuit

Your question caught my attention as I just added a ~ GE 60 Amp 240-Volt 240-Watt Non-Fuse Non-Metallic AC Disconnect on either side of my solar controller. If you put this in the search on Home Depots page you'll find it. It's a plastic box with a bar that pulls out to cut the circuit, no fuses or breakers. Cost $14. One of my brothers who was an electrical engineer onboard a sub said these disconnects were needed. Admittedly I was a bit dubious.
For your consideration.
__________________
hurricanehole is offline   Reply With Quote
Old 12-02-2014, 17:23   #27
Registered User
 
Dsanduril's Avatar

Join Date: Aug 2011
Location: South Pacific
Boat: Outremer 50S
Posts: 1,451
Re: Switch for solar panel circuit

Just a reminder to everyone, if the sun is out there is voltage on the panel leads. Once you open the disconnect that voltage will go up to Voc. If you are working on the panel side of any disconnect (including wiring said disconnect) either cover your panels or understand how to work on hot wiring.
__________________
Dsanduril is offline   Reply With Quote
Old 13-02-2014, 05:45   #28
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Switch for solar panel circuit

Quote:
Originally Posted by Dsanduril View Post
Just a reminder to everyone, if the sun is out there is voltage on the panel leads. Once you open the disconnect that voltage will go up to Voc. If you are working on the panel side of any disconnect (including wiring said disconnect) either cover your panels or understand how to work on hot wiring.

A couple of MC-4 connectors at the panel can suffice for the few times you may need to disconnect the panel side....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 13-02-2014, 06:22   #29
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Re: Switch for solar panel circuit

Greetings and welcome aboard the CF, hurricanehole.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 15-02-2014, 11:44   #30
Registered User

Join Date: Feb 2014
Location: NC
Boat: Prout 34
Posts: 32
Re: Switch for solar panel circuit

Thanks for the welcome. While I've lived aboard for 7 years and worked as a contractor for twelve onboard cruise ships haven't done much cruising except to the Abacos. I enjoy the company on this site. Thanks for the work you do here also.
__________________

__________________
hurricanehole is offline   Reply With Quote
Reply

Tags
solar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:18.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.