Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 05-09-2012, 15:50   #1
Registered User

Join Date: Sep 2009
Posts: 331
Breaker / Fuses MPPT-Solar Panels?

reading manual from morningstar about my MPPT.

They say I must have a breaker/fuse between both solar panels and mppt & mppt and batteries.

Are you all people doing this too? Or is it just the formal way to do it?
__________________

__________________
andreas.mehlin is offline   Reply With Quote
Old 05-09-2012, 16:09   #2
Registered User
 
GeoPowers's Avatar

Join Date: Dec 2008
Location: Gulfport, MS
Boat: Beneteau 393
Posts: 947
Images: 27
Quote:
Originally Posted by andreas.mehlin
reading manual from morningstar about my MPPT.

They say I must have a breaker/fuse between both solar panels and mppt & mppt and batteries.

Are you all people doing this too? Or is it just the formal way to do it?
Yes, that is how I set mine up. I used breakers for both, with the breakers as close as I could to the panels and the batteries, respectively.

Frank
__________________

GeoPowers is offline   Reply With Quote
Old 05-09-2012, 16:18   #3
Vendor
 
witzgall's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,773
Re: Breaker / fuses MPPT-Solar panels?

Yes, you need both. To protect the panels, and to protect against a short that could start a fire between he controller and the batteries.

Chris
__________________
witzgall is offline   Reply With Quote
Old 05-09-2012, 16:31   #4
Registered User
 
Albro359's Avatar

Join Date: Jun 2009
Location: Elyse is in Fiji
Boat: Amel Super Maramu 2000
Posts: 510
Re: Breaker / fuses MPPT-Solar panels?

Agree...that's my setup too
__________________
See you out there ....... Alan S.V. Elyse
now http://svelyse.weebly.com
older http://voyagesofDIVA.weebly.com
Albro359 is offline   Reply With Quote
Old 06-09-2012, 11:27   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,569
Re: Breaker / fuses MPPT-Solar panels?

What good is the breaker on the solar side going to do? If you have for example a panel that will put out max 20amps, you have a cable that can take max50 amps and you use a breaker at 25amps. If the able gets a short, the panels will never go above 20amps, so the breaker will not trip.
The breaker on the battery side makes sense, as much larger currents are available.
__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is offline   Reply With Quote
Old 06-09-2012, 13:07   #6
Vendor
 
witzgall's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Eastern Shore, MD
Boat: Camper Nicholson 44 Ketch
Posts: 1,773
Re: Breaker / Fuses MPPT-Solar Panels?

As I understand it, it protects the panels. A short could damage the cells, or the diodes.

Chris
__________________
witzgall is offline   Reply With Quote
Old 06-09-2012, 13:56   #7
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,569
Re: Breaker / Fuses MPPT-Solar Panels?

Quote:
Originally Posted by witzgall View Post
As I understand it, it protects the panels. A short could damage the cells, or the diodes.

Chris
Breakers don't trip because of a short, they trip because of current passing through them that exceeds their rating. Where is this current going to come from if only the panels are available to supply it?
__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is offline   Reply With Quote
Old 06-09-2012, 15:14   #8
Registered User

Join Date: Dec 2008
Location: Oriental, NC
Boat: Mainship Pilot 34
Posts: 1,429
Re: Breaker / Fuses MPPT-Solar Panels?

I agree with Paul L and I don't believe that shorting a solar panel will harm it. Does anyone have any specific references to support this view.

If correct, the breaker would have to be sized just right: high enough to pass the I maximum power point but low enough to trip at I short circuit. On a Kyocera 135 watt panel, there is less than an amp difference between the two. What kind of breaker is going to deal with that?

David
__________________
djmarchand is offline   Reply With Quote
Old 06-09-2012, 15:25   #9
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
PV panels are a current source, they can't be affected by a short.

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 06-09-2012, 15:45   #10
Registered User

Join Date: Aug 2010
Location: Beaufort, SC
Boat: 2004 Hunter 41 AC
Posts: 308
Re: Breaker / Fuses MPPT-Solar Panels?

Blue Sky's installation guides appear to have a fuse between the controllers and the batteries, but not between the solar panels and the controller. Not sure what other mfg's require, but since I have a Blue Sky unit in transit from SALT Service I plan on installing per their manual. YMMV....

Scott
__________________
s/vPainkiller is offline   Reply With Quote
Old 06-09-2012, 17:51   #11
Registered User
 
GeoPowers's Avatar

Join Date: Dec 2008
Location: Gulfport, MS
Boat: Beneteau 393
Posts: 947
Images: 27
Quote:
Originally Posted by Paul L
What good is the breaker on the solar side going to do?
It makes it pretty handy to isolate the MPPT controller for maintenance and/or isolate the panels as a power source in case you are generating power from other sources.

Frank
GeoPowers is offline   Reply With Quote
Old 06-09-2012, 18:00   #12
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,569
Re: Breaker / Fuses MPPT-Solar Panels?

Quote:
Originally Posted by GeoPowers View Post
It makes it pretty handy to isolate the MPPT controller for maintenance and/or isolate the panels as a power source in case you are generating power from other sources.

Frank
You still have the breaker between the MPPT and the batteries to shut off power source to your system. What we are talking about here is another breaker between the panel and the MPPT controller.
__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is offline   Reply With Quote
Old 06-09-2012, 18:41   #13
Registered User
 
ExRonin's Avatar

Join Date: May 2012
Posts: 23
As commented on other threads I recommend installing a relay (30A auto style) between the PV and the MPPT. This not only allows isolation of the MPPT for maintenance, but also allows the solar regulator to be turned "off" to prevent conflicts with other regulators (shore charger, alternator, etc). As far as am breaker or fuse between the MPPT and the PV this makes no sense as commented by others. Fusing between the MPPT and batteries IS important.
__________________
ExRonin is offline   Reply With Quote
Old 06-09-2012, 19:11   #14
Registered User
 
GeoPowers's Avatar

Join Date: Dec 2008
Location: Gulfport, MS
Boat: Beneteau 393
Posts: 947
Images: 27
Re: Breaker / Fuses MPPT-Solar Panels?

Apparently it makes sense to MPPT manufacturers such as Morningstar and Outback. The relay and breaker or fuse support the same notion, but I would check the max operating voltage of the auto relays carefully as they are sold for 12V systems. My system typically puts out 85-95V, with a Voc higher than that. When I looked into this I found a few around 27v, and the max operating or "switched" voltage I could find was 50V.
GeoPowers is offline   Reply With Quote
Old 06-09-2012, 19:19   #15
Registered User
 
ExRonin's Avatar

Join Date: May 2012
Posts: 23
Re: Breaker / Fuses MPPT-Solar Panels?

GeoPowers

Fair point on voltage rating for the relay. I typically deal in 12V systems with 17V or so output panels in parallel, where a 30A auto relay is absolutely appropriate. In higher voltage systems, a more appropriate relay, such as an Omron (available from Digikey.com) can be used. Further to my prior post, here is a sample system diagram:
Attached Files
File Type: pdf Solar.pdf (16.2 KB, 129 views)
__________________

__________________
ExRonin is offline   Reply With Quote
Reply

Tags
fuses, panels

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 13:16.


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.