MPPT vs. Shunting Solar Controller - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems
 Not a Member? 


Like Tree3Likes
  • 3 Post By Maine Sail
Reply
 
LinkBack Thread Tools
  #1  
Old 11-25-2012
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,286
Thanks: 10
Thanked 117 Times in 85 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
MPPT vs. Shunting Solar Controller

I get asked quite a bit to describe the difference between an MPPT (multi-point power tracking) solar controller and non MPPT controllers.

Basically all 12V nominal solar panels run voltages of 16 - 18V+. With a PWM or shunting controller the excess voltage goes to waste when the panel voltage is stepped down to a safe charging voltage. An MPPT controller can convert this excess voltage to current so there is less waste and more efficient charging..

To show how this works I decided to use my bench top power supply to simulate a solar panel yet provide consistency in output for an A/B scenario. I set the power supply at 17.4V and 4A or the rough equivalent to a 70W solar panel. I then fed the power supply through a switch to choose which solar controller got the power. I used a battery bank that had been depleted to "bulk" for the 4-5A of current it would see.

The video below shows the results. Basically the MPPT controller had an output of roughly 22% - 24% more than the simple shunting controller. There is no magic just an A/B switch and two different solar controllers...

Hope this helps give some clarity...


night0wl, FarCry and GrahamO like this.
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
  #2  
Old 11-26-2012
FarCry's Avatar
Freedom 39
 
Join Date: Apr 2007
Location: St Thomas USVI
Posts: 901
Thanks: 0
Thanked 14 Times in 13 Posts
Rep Power: 8
FarCry is on a distinguished road
Re: MPPT vs. Shunting Solar Controller

Great video!!!
Reply With Quote Share with Facebook
  #3  
Old 11-26-2012
asdf38's Avatar
Senior Member
 
Join Date: Jul 2010
Posts: 682
Thanks: 1
Thanked 4 Times in 4 Posts
Rep Power: 5
asdf38 is on a distinguished road
Re: MPPT vs. Shunting Solar Controller

Great video, I'll just throw in another analogy in case it helps.

The MPPT controller is like a transmission in a car. The transmission seeks out the most efficient ratio to convert the torque/RPM's (voltage/current) from the engine (panel) to the torque/RPM's it needs to drive the car (charge the battery). It can convert torque to RPM's and vice versa.

The transmission does the conversion efficiently AND lets the engine operate at the ideal point. Both are good.

The shunting controller on the other hand is like a clutch. It can only reduce the torque/RPM's it's given by allowing slippage and creating a heat in the process.

So the clutch is both inefficient at doing the conversion (because it creates heat) AND limits the freedom of the engine operating point. Both are bad.
__________________
1979 Contessa 26
Boston, Ma

Last edited by asdf38; 11-26-2012 at 11:22 AM.
Reply With Quote Share with Facebook
  #4  
Old 11-26-2012
Senior Member
 
Join Date: Aug 2006
Location: Arlington, VA
Posts: 1,808
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 9
btrayfors will become famous soon enough btrayfors will become famous soon enough
Re: MPPT vs. Shunting Solar Controller

Another wonderful effort by MaineSail! Thanks, RC.

I certainly agree that MPPT controllers can be very useful, and I believe they're well worth the cost.

Not mentioned in your video is the effect that MPPT controllers can have when multiple solar panels are connected in series, boosting the OC voltage to 36, 60 or even higher. In this scenario, the MPPT controllers are even more effective in using the available energy from the panels to charge the house batteries.

Another advantage of using panels in series: in low light levels (e.g., early morning or late afternoon or cloudy conditions), the panels still put out enough usable voltage for battery charging.

Bill
Reply With Quote Share with Facebook
  #5  
Old 11-27-2012
chucklesR's Avatar
Senior Member
 
Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Posts: 5,977
Thanks: 10
Thanked 30 Times in 30 Posts
Rep Power: 9
chucklesR is a jewel in the rough chucklesR is a jewel in the rough chucklesR is a jewel in the rough
Re: MPPT vs. Shunting Solar Controller

So, for a 500-600w panel array of these puppies (http://www.motechsolar.com/en/doc/mo...lear3BB_A4.pdf ) - which MPPT would you have on YOUR boat?

I'm looking at the midnite classic, haven't bought anything yet.
__________________
Lessons learned are opportunities earned.
Reply With Quote Share with Facebook
  #6  
Old 11-27-2012
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,286
Thanks: 10
Thanked 117 Times in 85 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: MPPT vs. Shunting Solar Controller

Quote:
Originally Posted by chucklesR View Post
So, for a 500-600w panel array of these puppies (http://www.motechsolar.com/en/doc/mo...lear3BB_A4.pdf ) - which MPPT would you have on YOUR boat?

I'm looking at the midnite classic, haven't bought anything yet.
I like the Outback & the Morningstar controllers and also use a lot of the Blue Sky controllers but you really need the extra IPN Pro remote to set them up properly...

On my own boat I have a Genasun but the array is only 140W........
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Aurinc Blixt 20+ MPPT Solar Controller colinflteng Electrical Systems 2 07-04-2012 11:27 PM
MPPT Controller for 270w of solar and a wind genny Sailor_Rob Electrical Systems 3 06-16-2012 11:14 PM
Inexpensive MPPT Controller cb32863 Electrical Systems 9 02-20-2012 02:38 PM
MPPT Solar Caution ... wind_magic Electrical Systems 8 02-21-2010 08:10 PM
MPPT Controller is it worth the update. SimonV Gear & Maintenance 10 03-08-2008 04:49 PM


All times are GMT -4. The time now is 06:25 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.